Summer Open Thread (#2)

I hear from my good friends in Indonesia that Krakatau has started to erupt again :)

With all those quakes in the Aleutian islands Alaska it's no wonder one of those babies up there is smoking.

More nicely sized quakes down in Vanuatu today.

Augustine is old news,

http://www.avo.alaska.edu/volcanoes/volcact.php?volcname=Augustine&erup…

Seismic activity is reported by AVO to be at or near normal background levels.

Kamchatka is percolating along in typical fashion. KVERT reported last week:

SHEVELUCH, KLYUCHEVSKOY and KARYMSKY: ORANGE
GORELY and BEZYMIANNY: YELLOW

Maybe we can put this mostly dull thread to "effective use".

First, you should wander over to Chris Rowan's blog, Highly Allochthanous, for his kickass followup post on the Yellowstone supervolcanic eruption ash and the Lava Creek Tuff deposits.

http://all-geo.org/highlyallochthonous/

Y'all come back here, and we'll answer Lab Lemmings question in comment to Chris' post today, on the unique chemical signature of LCT.

Geotimes Feature Article, 'Yellowstone and Heise:
Supervolcanoes That Lighten Up'

www.geotimes.org/nov07/article.html?id=feature_yellowstone.html

Then it might be time to add to our Big Picture understand of How Things Work, with a technical chitchat about that pesky Aleutian Chain EQ activity.

The loess bluffs in and around Vicksburg MS (which proved to be militarily advantageous during Civil War) are an accumulation of dust blow in off of the Mississippi river delta. Mostly ground up glacial till in origin, they also have a volcanic ash content (as per the docu-tourist film at the welcome center), though I have never seen an analysis of which volcano contributed to it. I do know that this easily carved soil afforded shelter during the siege, provided you had enough beans and hardtack to make it through the day.

@6, yes, deposits carried downriver from Kansas, Nebraska and Iowa.

Ash Deposits Can be Deceiving.
http://www.aapg.org/explorer/2006/12dec/ash_gulf.cfm

an interesting link,notice reference at the end...
/www.nunatsiaqonline.ca/stories/article/110810_Baffin_Island_lava_fields…

the rest of the link reads _offer_clue_to_Earths_rocky_start/
sorry, it won't work without that, but it didn't transfer with the copy/paste.

A BIG eruption... in my face :-)

From the end of the Baffin Island news story, mentioned by birdseye:

>The scientists say the magma plume that gave rise to the Baffin Island rock also created enormous lava beds in Greenland. They say the plume is still active and responsible for the volcanoes in Iceland that played havoc with air travel earlier this year.

Nature articles: editorial, News and Reviews synopsis and the Letter Article (if you have subscription access).
www.nature.com/nature/journal/v466/n7308/edsumm/e100812-06.html

'Relative to terrestrial-mantle He, there are extremely high 3He/4He ratios in the solar wind (roughly 310âRa, where Ra is the present-day 3He/4He ratio in the atmosphere, 1.38âÃâ10â6; ref. 8) and the atmosphere of Jupiter (120âRa; ref. 9), a geochemical characteristic that is associated with the building blocks of planets. On Earth, He is continually degassed from the interior during mantle melting and volcanism, and is lost from the atmosphere by gravitational escape to space. Within the solid Earth, the α-decay of U and Th replenish 4He, but crustal recycling does not replenish the mantle 3He.

Therefore, recycling results in a long-term decrease of 3He/4He ratios in all terrestrial geochemical reservoirs over time, and the terrestrial mantle may no longer have such high primordial 3He/4He ratios. Nonetheless, the mantle sources of some ocean-island basalts preserve relatively high 3He/4He ratios (more than 30âRa), for example, Hawaii the Galapagos Islands Samoa, Iceland and the proto-Iceland plume.

The highest terrestrial mantle 3He/4He ratios (up to 50âRa) were measured in roughly 60-Myr-old Baffin Island and West Greenland lavas, a manifestation of the proto-Icelandic hotspot. However, such high 3He/4He ratios are extremely rare, and the origin, composition and long-term survival of the high-3He/4He reservoir in the Earthâs mantle are poorly understood.'

Nice catch, birdseye.

In Chris Rowan's Highly Allochthanous blog post on Yellowstone Caldera ash deposition, I replied to Lab Lemmings comment, posted additional info, and LL responded with another comment with two excellent, must-read Yellowstone Geology Basics webpages.

We're carefully keeping Yellowstone technical discussion on Chris' blog and Eruptions blog Summer Schedule thread, because we're churning through Cascade Subduction volcanism of the Pacific plate in another thread, as intro to Aleutian Island Arc subduction and volcanic seismicity this week, in this thread.

That will leave the third most interesting and important spot for volcanic activity on Earth (after Iceland and the PRoF), Italy and Sicily: our friend Boris Behncke's technical forte.

Several of you have noted past increases in tremor activity around Grimsfjall in recent weeks and the surrounding area, and wondered if this could signal increased activity below the ice. We appear to be having a small flurry of 2+magnitude of quakes mostly around Hamarinn, mostly shallow depth of 1km or so. Would this higher magnitude of quake support that theory, or could this still be to do with ice movement? Thank you.

Greg #1:

Krakatoa erupting? Did you have a link for that? I have googled like crazy and not found any news on Krakatoa erupting.
My guess was that it would erupt after the twentysecond of January 2011, when I go home from Sunda Strait. That based on the "fact" that all volcanoes erupt after me passing them in a sail-boat... :)
The correlation between me sailing and large volcanic eruptions is n=2 sofar:)

@11 passerby, thanks for the added info, a fuller explanation helps. I troll the (circumpolar) northern news every so often just in general.

Fall AGU meeting in San Francisco, two sessions related to Iceland and Eyja.
www.agu.org/meetings/fm10/program/scientific_session_search.php?show=de…
and =751

Pretty dull out there with volcanoes. Nothing to look at or worry about, I am bored for now.
I am grateful no one is in harms way but I want some action.
Maybe a nice Alaskan blast on a web cam away from civilization just large enough to reverse some global warming for a few years.
Thats the ticket

Pretty dull out there with volcanoes. Nothing to look at or worry about, I am bored for now.
I am grateful no one is in harms way but I want some action.
Maybe a nice Alaskan blast on a web cam away from civilization just large enough to reverse some global warming for a few years.
Thats the ticket

#16 @birdseyUSA Thank you. It would be very interesting to attend such a meeting. Any candidates in CA who could keep us updated? :)

#19 @Renato

It is clearly tempting to attend this session, but a day pass for non-members runs at $ 205. That's a bit more than what I would want to spend for such an occasion :-(

Sneaking it wouldn't work either, security is pretty well organized at the Moscone Convention Center. I know since attend meetings at that center almost every year. Too bad, but maybe Erik Klemetti can give us an update on the latest developments?

#20 @Holger, N California :-(
Too bad indeed. Thankfully "we" have developed "our" own Eyjaf's story lurking from the background here.
And yes, maybe Erik could invite some "guest bloggers" from this event, uh? ;)
I'm pretty sure that some of these guys might have peeped in our threads a couple of times and may even have dropped some comments here and there.
(BTW: 250 bucks isn't a bit too much?)

#21 @Renato

Actually, that's pretty much the standard rate for a scientific conferences of that nature i.e. organized by a scientific society. Commercially organized conferences can be much more expensive e.g. $ 1,500 or there about.

But that's a good idea, maybe Erik can recruit some other scientists from that conference to write about their work on this site.

#22 @Holger, what are you telling me! For this amount of money I'd rather buy tickets for the Salzburger Festspiele! No wonder this kind of secretiveness gives way to so much apocalyptic mongering. Are we talking about "the Scientific Illuminati" here?
Well, let us see what Erik can do about it. Thanks for the update.

Anyone interested in earthquakes and rain/groundwater interaction might pay to keep an eye on the upper end of the Taupo volcanic zone (stretching from Okataina up to the coast). Not only are there are couple of very active swarms going on in this region, the crust is extremely thin here and moving apart quite fast.

The interesting bit is that heavy rain is forecast for the region over the next 36 hours (28 mm) which adds up to a lot of weight, so we might see an uptick in activity if this plays any kind of a role. Here's the one to watch:

http://www.geonet.org.nz/volcano/activity/okataina/index.html

PS, don't hold your breath though!!

take a look at these helicorders. It's amazing how clearly the ecuador 7.2 quake is visible on almost all the stations.

http://www.simnet.is/jonfr500/earthquake/tremorusgsen.htm

@Stephan:
This was an "intermediate-depth earthquake" and such quakes can be felt from very far. Yesterday's jolt scared people in 4 countries (Ecuador, Peru, Colombia and Brazil, which has no border with Ecuador). Thankfully they don't cause much damage, and so far, no aftershocks.

If all goes according to plan, I will be at the AGU meetings because my other half participates in other sessions and I get to go as a guest. will be sure to attend and at least get the summary of the Eyja sessions posted here, plus whatever I can glean/remember. Looks as though someone from IMO will be one of the presenters. (Each session involves a number of topic-related papers and there are usually related poster sessions as well, normally grad students showing and explaining their work. I can get titles and contacts for those.) Oh goody, a job! I usually focus on the geocryology/arctic stuff.

@birdseyeUSA:
You are our man! May the hands of Zeus Almighty and Thunderbolt Hephaestus guide your steps through this elevated mission. Meanwhile, us, mortals, anticipate your return in excitement and jubilation. :)

@ Renato RIo - I'll do my best, but you have to wait 'til at least mid-late December! And possibly I have to get permission to post some of the abstracts - we'll see what I can do, I'll do the best I can, maybe a 'Happy New Year' gift to this blog which has given me so much.

Heh- looks like I will need some helpers - I just checked 'Iceland -all session' instead of just 'volcanology'...sometimes these things run concurrently -

Listing of All Sessions
Number Title
AE07:Volcano Lightning
B57:Geochemistry and Geobiology of Terrestrial Thermal Systems
NH04:Hazards Associated With Snow- and Ice-Capped Volcanoes
NH07:Remote Sensing of Volcanic Aerosol and Gases Using Ground-Based, Aircraft, and Satellite Observations
V05:The 2010 Eruption of Eyjafjallaj�kull � A Landmark Event for Volcanic Cloud Hazards
V07:Tracking Magma Through the Crust to Eruption Geodesy

@birdseyeUSA: feel free to pick the ones you fancy, or else it could get boring. We'll benefit from any information you might kindly share with us.
I'm also looking forward Erik's compilation on Eyjaf.
Thx once again.

Only indirectly volcano related, but this was in the news this morning:

http://www.metro.co.uk/news/837945-volcano-bacteria-in-lake-diamante-ma…

(Diamante Lake seems to have existed only since 1826 BTW)

Hi all

Today there is some seismic activity concentrated southwest of Azores islands in the Mid-Atlantic Ridge. Nine earthquakes with an intensity around 4/5, and all in the same area, and about 10kms deep.

http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/quakes_all.php
http://www.meteopt.com/forum/sismologia-vulcanismo/sismos-portugal-2010…

Any expert here who can tell whether earthquakes are tectonic in nature or may be of volcanic origin?
Thank you.

I was looking for info on Azores swarm and found another big one:
Magnitude 7.2 - MARIANA ISLANDS REGION

@Luis:
I was trying to grasp some information from the link you provided, but so far this remains a tectonic quake swarm. Local people are saying they have never heard of a similar event on the region (neither have I on a divergent plate boundary). But I'm no expert. I thought it could be volcanic, since they all occurred on a very same spot, and we must not forget that the Azores are located on a triple junction, over a hotspot, with seven active volcanoes, some submarine.

What a busy 2 days for earthquakes, there was just a a 7.2 Magnitude in the Marianas Islands and a 6.0 in the Philippines and then add that to the 7.1 in Ecuador yesterday. They said on the news the other day that the earth usually only sees about 15 7+ magnitude quakes in one year, I wonder what's going on to give us a 7+ magnitude quake 2 days in a row.

While trying to find out what is happening in August 2010 with the named Volcano in Iceland that very few people can spell, I found one Icelander who thought it was no big deal. So much for using them as an eyewitness source. ...

http://www.allvoices.com/contributed-news/6514316-iceland-volcano-curre…

@37: Mariana islands shake:

neic.usgs.gov/neis/eq_depot/2010/eq_100813_zxcf/neic_zxcf_s.jpg

Now that is one tectonically varied and busy region: ridges (2), subduction zones and transform faults. Oiya!

@Passerby
It's amazing, indeed. And this one was quite shallow (4.7 km)just to the North of Challenger deep, if I'm not mistaken.
I think I can now better understand earthquakes happening on subduction zones (I've been doing my homework).
As for the Azores cluster, it kind of intrigued me. There are discrepancies between data from USGS and EMSC and I am not sure if it happened on the divergent sector of MAR or in between, over its transform perpendicular segments. But there's a slight N-S orientation, and I have no memories of similar occurrences. There was also a small event, not showing in USGS report, over the dangerous Azores-Gibraltar fault zone too. But maybe not related to this.
Do you think it could be volcanic?

Vanuatu quakes seem to be occuring along a horizontal line which suggest plate movement rather than volcanic activity. The Azores a little harder to tell but they were fairly big. I wouldn't speculate more movement underground than usual because I've only recently started to pay attention to when and where these quakes are occurring.

Azores EQ map. Note the characteristic zig-zag pattern. You can see it's relatively active seismic portion of the MAR.

neic.usgs.gov/neis/bulletin/neic_zxbt_h.html

This map shows the earthquakes today occur near the Azores Triple Junction on the Mid-Atlantic Ridge.

earthquake.usgs.gov/eqcenter/recenteqsww/Maps/10/320_75.php

From the Wiki-page on Divergent Boundaries:

'...Divergent boundaries can create massive fault zones in the oceanic ridge system. Spreading is generally not uniform, so where spreading rates of adjacent ridge blocks are different, massive transform faults occur. These are the fracture zones, many bearing names, that are a major source of submarine earthquakes. '

@Passerby: Thank you once more. It just showed a weird pattern, all quakes of around 5 happening in a row. It's over now. Hope it stays so.
Just trying to flee from the horrible images in Pakistan and Russia, but, as you clearly explained in the other thread, what else can we expect from environmental deterioration of overpopulated areas? And who gives a damn about it?

Katla has started to show a sign of inflation. But one GPS station has started to move south.

That GPS station is called HVOL and has currently moved about 10mm to the south. It has also moved a little bit to the west, but that movement is really small. This change is rather sharp. But if it continues is a good question that only time is going to answer.

@jon, #44: Tremor around Eyjafjallajökull is also rising. Not much compared to the time of the eruption but much more than before.

Ref: Passerby[42]

"...Divergent boundaries can create massive fault zones in the oceanic ridge system ... fracture zones, many bearing names, that are a major source of submarine earthquakes..."

Speaking of transform fault zones, heres a good way to kill a Saturday.

Previously, I've done temporal plots of the San Andreas, plotting the quakes by latitude verses time. With the spate of recent quakes along the MAR, I decided to do one of the segment that has been making noise. Getting carried away, I did the plot from the intersection of the Barracuda FZ all the way up to the lighthouse in Iceland, right about where the MAR comes ashore.

The query nodes along the MAR are right at 100 km apart, and the queries were for all quakes within 100 km of the node. All the data was dumped into one spreadsheet, and then duplicate events were removed.

I expected to see moving clusters of quakes, either up or down the MAR, but nothing really pops out and says "look at me."

Enjoy.

http://i37.tinypic.com/6jqd5s.png

>http://hraun.vedur.is/ja/Katla2009/gosplott.html

Huh? (at #45).

@43: We didn't talk about other places hit hard by prolonged drought from LaNina: Niger. They also got hit with heavy rains and flooding after a long dry period that killed off their livestock and decimated crops.

It's purported to be the worst flooding for Niger in 80 years, but flood and famine hit at a time when global relief resources have been depleted by a succession of disasters in the last few years and haven't been replenished by developed nations who are still mired in recession.

(the WSJ reported today that as few as 61% of the US workforce is presently employed, a number lower than post-war era (85%) and approaching that of the Great Depression (55%), a time when few women worked outside of the home - a telling statistic, if it's true)

Per Pakistan: The Hindu (newspaper) reported today that Pakistan has asked explicitly for help from India, who shares some of the blame for flooding of the Indus River basin. The request was framed in an interesting context:

As a business opportunity for India. Whether India and Pakistan can use this epic disaster to bridge neighbor relations and restore trade remains to be seen.

@Chris, Reykjavik, Those are subsiding tremors I think. Far as GPS data and other indicators are concerned Eyjafjallajökull is quiet and shows no signs unrest after quieting down in May.

I believe that Eyjafjallajökull eruption is over for the moment, unless something changes fast soon.

#47 "Whether India and Pakistan can use this epic disaster to bridge neighbor relations"
@Passerby: I think governments all over the world could use some of your objectivity and lucidity: facts and numbers clearly placed in short sentences. But all they do is the everlasting political blabber.
#46 @Lurking I think I can "see" something in your plot between 1996 and 2000.
#44 #48 @Jón FrÃmann: Thanks for keeping us updated. We are all ears.

@Jon, #44, where can one see this? This plot does not seem to show that, hvol looks to have a constant trend in all graphs:
http://hraun.vedur.is/ja/englishweb/gps/cts/emyrfr2004.html

@Ursula, you can see it here, hraun.vedur.is/ja/gps/predorb/hvolpred.html

The long term GPS plot that you linked to is interesting.

@Jón, @Ursula -
I rather use this http://notendur.hi.is/runa/HVOL.png link; the data is "detrended", which I take means the effect of local conditions that might affect the measurements: temperature, continental rift, etc.

IMO, the movement at HVOL is next to none.

For once, not one EQ recorded at Mýrdalsjökull area for the last 48 hours, as of 15:45 GMT: http://en.vedur.is/earthquakes-and-volcanism/earthquakes/myrdalsjokull/

#53 @Kultsi, I've noticed that too. But if you look at USGS world's report you'll see that it has been the busiest 48 hours this year. More than 30 quakes over mag. 5+.

In case you've tried to se anything at THORO cam today...
www.icenews.is/index.php/2010/08/15/risk-of-flash-glacial-flood-in-sout…

Very good article explaining data detrending and why it's used.
http://www.ltrr.arizona.edu/~dmeko/notes_7.pdf

Kultsi, in citing the detrended HVOL plot, is pointing to 'business as usual' for this most-eastward GPS station, with the exception of an brief elevation excursion in early 2008.

But I think we should look more closely at Ursala's link. Bookmark it, because it's a relatively important piece of evidence that helps us understand the Big Picture affecting activity at Eyjaf and Katla.

This was one of the key bits of data that I used to explain the larger forces acting on the maritime icecapped volcanoes, back in April here at Eruptions.

Motion is to the east and south, with a twist arching northwards, centered roughly under the intersection of Katla and Eyjaf.

That's the SISZ, pushing at the geological structures to the east, with the force-moment couple reflecting the right-hand twist (stick your right thumb in the air and curl your fingers toward your palm) torsion of the south half of the transform fault.

You can see this in the sharp deflections of two stations in the GPS northward motion component graph.

Interestingly, the offshore VMEY station is 'keeping up with the Joneses' in eastward motion, doesn't show nearly as much elevation increase over time (expected) nor northward drift. The SISZ motion extends offshore dragging the southward extension of rift (right-most yellow band that actually runs off the southern coast to the Islands).

Still very little EQ activity over Iceland, in the meanwhile, today's USGS report figures keep growing.

I understand the logic of detrending the data, but one underlying nagging question remains. What is the source of the trend.

Plate movement as the listed stations move away from REYK? Likely, but where is the displacement seen in the terrain?

Equipment degradation or aging? Possible, but at what source? The stations themselves or artifacts showing up in the satellite network? One would expect the stations to show different aging characteristics and not track with each other. If it were the satellite constellation, there would be some serious gnashing of teeth at the amount of change that is occurring.

So, it seems that the first candidate is the likely one. That then leads us to image #3. That leans towards the whole region experiencing 80 mm of uplift over six and a half years. Is this rate what would be expected from post glacial rebound?

Makes ya think.

>What is the source of the trend?

I told you, the SISZ. The transform fault is moving (if we are looking at a map oriented nor, heading to the right above the fault and to the left, below the fault.

>Plate movement as the listed stations move away from REYK?

Correct. Equipment malfunction is unlikely, as it's (a) checked regularly and maintained and (b) a group of instruments would not be expected to have bias in one direction.

>but where is the displacement seen in the terrain?

That would be a small, incremental delta(X) over a large expanse of ground. What were you expecting?

>Is this rate what would be expected from post glacial rebound?

Post-glacial rebound of Iceland during the Holocene. (2010)
http://jgs.lyellcollection.org/cgi/content/abstract/167/2/417

Could be. The uplift rate is variable, depending on crustal thickness and relaxation period. We have a plot for crustal thickness for south Iceland, right?

From the ISGPS plot, THEY, one of two coastal GPS stations, changes the most, and offshore VMEY the least.

I told you the offshore MAR places a counter force on west end of the SISZ and there is an opposite force from the continental ridge at the east end. A similar (but much more complex force-couple system) situation exists on the Tjornes northern transform fault.

The first thing I do when I am trying to unravel a difficult puzzle of cause-and-effect, is to make an engineering mechanics body-force diagram, after reviewing as much information as I can lay hands on.

Mainly, the questions concerned the idea of the trend being there in the first place.

More of general purpose thing.

As for the uplift link, that's enlightening. At the â80mm over 6 years, that comes out to around 1.3 cm/yr. In the link, the rates are 2.1 to 9.2 cm/yr (over a 1150to 2500 year period roughly 9070 yrs ago), so the speed of the current uplift seems to fit with the idea of declining uplift rates.

"That would be a small, incremental delta(X) over a large expanse of ground. What were you expecting?"

Well, what I was expecting is some feature of the terrain where this seems to occur. The potential site of a Laki style event. This would be a hazardous place to be. Being spread over a large area, though most likely, is problematic. You can't point to a spot and say "stay away from that."

@Passerby, #59, somewhere along the line, I missed what SISZ is. Yeah, I know it was posted looooong ago, but my brain is not remembering so please let me know. Thanks.

@Diane N CA : I think it refers to South Icelandic Seismic Zone, @Passerby, correct me please if I'm wrong. Whatever it is, @Lurking, I don't think that no one, not even the brave Icelanders, can live with the idea of their homeland being torn apart. For now, it's all still and peaceful - and beautiful, as usual.

SISZ intro:
hraun.vedur.is/ja/prepared/SouthIcelandEarthq2000/node3.html

Earthquake prediction research in the South Iceland seismic zone and the SIL project. Bulletin of the Seismological Society of America (1993)83(3):696-716.

'South Iceland seismic zone (SISZ), where most destructive earthquakes in the history of iceland have occurred. The zone has many characteristics of a transform zone and takes up east-west relative motion between two offset branches of the mid-Atlantic rift zone; i.e., the eastern volcanic zone of Iceland and the Reykjanes Ridge. Earthquakes in this area reach the magnitude of roughly 7 and tend to culminate in sequences with duration from a few days to a few years. These events are associated with right-lateral faulting on N-S striking faults arranged side-by-side along the E-W trending zone.

Thus, apparently the general left-lateral transform motion is accommodated by counterclockwise rotation of the fault blocks. The seismogenetic crust is 10 to 45 km thick and is underlain by partially molten mantle material. Earthquake swarms, slowquakes, and strain episodes are commonly observed in the zone and in its proximity.'

The South Iceland Lowland (SIL) project, started in 1988; the IceArray (large motion sensor array) program is a more recent addition to monitoring seismic activity on the SISZ. There's a wikipage that describes IceArray.

en.wikipedia.org/wiki/ICEARRAY

We've talked about magma intrusion on the Tjornes as being potentially responsible for swarm seismicity. This report seems to suggest that magma may also be the cause of uplift deformation under the SISZ as well.

SAR interferometry study of the South Iceland seismic zone.
hraun.vedur.is/ja/prenlab2final/node71.html

@Renato Rio

"...homeland being torn apart..."

That actually isn't really the issue. Everybody in San Diego will be able to walk directly East and go to Los Angeles if they wait long enough. The same applies to Iceland, but instead they are getting lots of new acreage every year.

Back to the linkage provided by Ursula at [50]. If you will note, the E-W trend is about twice the N-S trend. This directly supports a thought/paper kicked around on here a few weeks ago about Iceland expanding E-W faster than N-S. I think the central argument was that Iceland is a bit of continental crust laying on top of a segment of oceanic crust, and accounting for it's rather large thickness.

>I don't think that no one, not even the brave Icelanders, can live with the idea of their homeland being torn apart.

Renato Rio, Iceland is being *made*, not destroyed; although erosive action is also at work, it can can viewed as a formative process in the lowlands that trap transported sediment.

This hardy and stoic Nordic people long ago adapted to the geologic chaos of their beautiful and changeable landscape. Besides being frequent visitors to Eruptions, Icelanders have become more interested in their native geology in the past 5 months, as reported in their national news last week. Good!

Thanks, Passerby. That gives me a pretty good idea of what is going on there. It sounds like the fault systems almost rotate from right lateral to left lateral depending on what direction they are oriented to. Let me know if I am off base as I am still trying to get a grasp of it.

I wish I could go to Iceland. Maybe some day.

Thank you, too, Renato.

#64 - #67
I'm the one to thank my fellow bloggers to keep my gray matter working.
@Lurking: When you mentioned the Laki fissure event, the idea of Iceland being torn apart came immediately to my mind and I reacted to it in horror, even though I know that new land is formed in the process (but with a high price to "hardy and stoic" Icelanders).
@Passerby: Thanks for correcting me. I just didn't know if you were around and didn't want to leave Diane's question unanswered (I got close, though). I have a problem with acronyms and I sympathize with people that deal with a similar difficulty.
@Diane N CA: I followed your example and started to do some "geological inspection" in my neighborhood with amazing discoveries, so you too, have my thanks.
Love you guys!

Some positive volcano news:

http://www.guardian.co.uk/environment/2010/aug/16/rwanda-gas-lake-kivu

Thank you very much for this article!
For a long time I have done exactly what you warn against. This article was a slap in the face - but a needed one.
That being said, what is the value of an intuitive explanation? Is it to give a lay person an "ah-ha" moment? Is it good to have SOME understanding, even if it is "vague and mush?"

@parclair N CA
Methane harvesting? Very, very interesting. Maybe they could do the same in Lake Nyos, Cameroon, which went through a major CO2 disaster. They've put siphons there for releasing gas but with no profit.
see Wikipedia link: http://en.wikipedia.org/wiki/Limnic_eruption
How about Mammooth Lakes, I think they experienced a similar degassing event, didn't they?

@70: specify comment to which you are replying.

A 4.5 magnitude earthquake was observed a few km from island Lipari (north of Sicily) at depth of 19 km on Monday. I could not find any more detailed information on this to see, if it is connected to Stromboli...

@Passerby[72]

It's not me. Somebody is spoofing. I have no connection with http://www.greenreplica.com/

And, since someone is playing monkey games... similar to the advertising posts we have been seeing on the gaming clan forum posts, I'll make it up to all since the reprehensible idiot used my handle.

Regarding ancient rocks under neath Baffin Island:

"The evidence comes in the form of lava rocks that, themselves, are a mere 60 million years old. But these rocks contain an early Earth mixture of helium, lead and neodymium isotopes which suggest the mantle rock beneath the crust that yielded them is a virgin pocket of Earth's original material.

That pocket had survived for 4.5 billion years under Baffin Island without being mixed by plate tectonics or erupted onto the surface. "

http://today.msnbc.msn.com/id/38661354/ns/technology_and_science-scienc…

There probably a research paper somewhere that relates this if anyone is interesting in squirreling it out.

The Lipari quake was not connected to Stromboli, based on this map: http://earthquake.rm.ingv.it/earthquakes.php

@Renato Rio 71:

Sorry, we tried to do that in Nyos, but the methane levels are not commercially viable.
What you should though know is that this entire article is really old news... The gas deposites where found in 1937 in Kivu and the first pilot plant was launched in 1963 by Union Chimique Belge, now the gas-exploitation is run by Upegaz.
Even though I am fond of us being involved in the project as both investors and technology contributors I am a bit concerned about the CO2 emissions. But this time I see it as a lesser evil to pump it back into the "surface" water.
http://www.upegaz.gov.rw/Accueil.htm

Cameroon on the other hand would make a good case for a geothermal powerplant at Mongo ma Ndemi. But that all depends on the end results from Krafla Power Plant magma chamber drilling experiments.

Open question to anyone who can answer!

I know there is alot of EQ´s at approx 1km depth or so that is the result of the Myrdaljökull icecap shifting due to summer heat, melting and so on.

But what I cant get my head around is why 90% of all registered EQ´s in that area is in close proximity to GOLA station? Shouldnt there be more activity on the north and east side as well? (90% was just an estimate. I am aware that there has been a few "stray" tremors)

>There probably a research paper somewhere that relates this if anyone is interesting in squirreling it out.

*sigh* Done, days ago.

#77 @Carl
Thank you for the update and the cool link. Wish you guys luck.

@78/79maybe Iceland have started a fashion trend Gola trainers all that stamping around to get some activity going only joking i had a pair when i was young...according to past research Katla is most likley to Erupt after summer towards winter when some of the ice melted.maybe its were poss its next eruption going to be at some point in the near future or thats the gate way to the magma chamber as its goes along causing earthquakes only the future can tell @78 what research to you want i have loads on katla; but not on Gola

Re: Passerby

"*sigh* Done, days ago"

Okay, but I was probably busy reversing lat-lon labels.

Lurking, thanks for all the work you have done to give us the quake graphs. I wouldn't even attempt it. :-)

Renato, glad to hear you are studying the geology in your area. Let us know what you are finding.

As for my area, one side of the divide has limestone, ash deposits from pyroclastic flows, mud flows and what ever else I will find. The other side of the divide has a fault that runs through and on one side of the fault is serpentine that ranges from greenish black to white and the other side has vertical slatey rock, and quite a number of dikes that run from vertical to horizontal. There is some folding of rock, also.

As I have another chance to get out, I will let you know what else I find. BTW, some of the rock has a lot of quartz seams running in all directions.

Lurking...poorly. See my entry, this thread (#11), a follow-up to parclair's observant comment and news article.

I tried to morph and reorient your 3-D plot of Etna EQs to fit the Sicily geologic map to look for features that might explain the crustal EQ patterns to the west of Etna. No can do, need a north-looking representation of the 3-D map with the excellent topology overlay layer for reference.

Boris will have his hands full explaining the complex geologic setting and orogeny processes that apparently differs for volcanic islands like Stomboli and Vulcan to the immediate north of Etna.

I started to reply to your posted MAR temporal series graphic on Sunday, but lost my message from keystroke weirdness (some silly old software that got activated by mistake - two 3-key combinations shut my browser down on me. Grrrr!!). The only readily apparent feature is south of Iceland, a clear trend moving northward. The older data is suspect due to seismic station operation discontinuity (US Navy and others) that invites interpretive artifact.

@Eruption just wondering would it not be a good idea to have a share thing going so that we can simply send links to this website much quicker than writing it so if find a Useful link we can send it here!

#83 Diane N CA:
I found out that the complex huge gneiss-granitic formations that shapes the well known Rio skyline (like Sugar loaf, Corcovado etc) are all magmatic intrusions dating from 600 milions years ago (since separation of Gondwana)! They show some characteristics similar to what you have at Yosemite Park (granitic intrusions suffering lateral concentric cracks). But nothing like the products of recent volcanism as you have in California which make it's Geology so fascinating. But you should see the mineral collections here: even gemstones encrusted in many types of rocks and minerals from which I had never heard. Even yellow sulfur, that I have no idea how come it be there. They call this location a "geological paradise". I even found a small geological museum right next-door from where I work exhibiting fossils of different ages. Amazing. Now I know where to go in between classes when I am at the University, thanks to your useful hint. Keep me updated with your findings, and I'll try to do the same, but I'm afraid I'll need a lot of studying until I can even describe what I saw. (I took some pictures too).

@LEON That sounds like a good idea, a share thing website. Just tell us how and where and when.

@Jón FrÃmann (are you around?)
Are these recurrent darker disturbances in your helicorders caused by any source other than wind or human noise? (I do check wind speeds and they don't seem high enough to be blamed for them). I've been noticing these features for a week or so, and I have no expertise as to state if they are somehow connected to your recent observations of increases on Katla's tremors.
http://www.simnet.is/jonfr500/earthquake/tremoren.htm

@Passerby

"...readily apparent feature is south of Iceland, a clear trend moving northward. The older data is suspect..."

I knocked down the data series and focused on stuff north of the Hayes FZ, but I'm not too happy with how it turned out. I had the colors of the individual quakes corresponding to the magnitude and it made my eyes hurt. This is about as good as I can get it:

http://i35.tinypic.com/1cgsj.png

"need a north-looking representation of the 3-D map with the excellent topology overlay layer for reference."

Tell me the boundaries you want and I can put that together quite easily. My problem is knowing where to slice the data at. I saw this on Katla when some of Torfajöulls medium depth quakes showed up in a view north plot.

After fighting most of the day, I now have a good topological set for Sicily of about 3.7 million points if I need it. (provided the computer doesn't choke)

The plots with the mangled lat-lon lables only used the 37K point set.

@87 Renato Rio:
I have another theory for the tremors that show up at Jóns helicorders, but I am probably dead wrong. But here goes. If you look at the quake plot you will see a rather nicely placed quake 15km WSW of Hekla. Something tells me it is related to Jóns helicorder since it is in Heklubyggd. But I am probably wrong and it is just wind or Gola-dancers loosing weight.
Just a comment about Kivu. We do quite a lot of cool things trying to find new ways of generating power. Rn'D expenditures have reached ten percent annual turnaround. The reason for this is pretty obvious, problem is though that we nor anyone else have found a large source of clean energy. Just a bunch of small ones that aren't really commercially viable.
My current two cents are that we may have to go either for large scale geothermal plants, but as everybody here understands better than most that requires large amounts of studies since it might be rather dangerous to tap energy from volcanos. The other is ultra-large evaporation hydropower (immense investment, low running cost, insane amount of power, quagmired in politics, unknown environmental impacts), but even one plant like that could take care of all the power needs of Europe. And the third would of course be cutting the daytime/nighttime difference in power expenditure with large-scale solarpower-plants. The day to night difference in Europe could be cut with 70 square kilometres of solar-arrays in Sahara. Problem is that the arrays are still to expensive to ever pay off the investment.

@88 Lurking:
3.7 M datapoint geographic overlay computed against another dataset to create a 4D representation? My man, do you have a feline-animal-named Cray in your living-room? Or did I overcomplicate it...

OOPS EDIT!!! Lurking, is it you who are doing quake interpretations on a CrayXT4???

http://cray.com/Assets/PDF/products/xt/HECToRCaseStudy.pdf

#89 @Carl:
> "Gola-dancers loosing weight".
- Deffinitely a quite more interesting (and funnier) explanation.
>"Just a comment about Kivu."
- Did you mean Kivu, or Nyos? I thought that Kivo is already being taken care of.
>"it might be rather dangerous to tap energy from volcanoes."
- That's what came to my mind when you mentioned Mt. Cameroon (you called it by the other name, which is to difficult to remember). This is a very active and dangerous volcano, maybe more then Krafla, which they are taking for example, isn't it?
> "Problem is that the arrays are still to expensive to ever pay off the investment."
- Do you think if there were more interest in investing on research over solar energy arrays, budgets would decrease, or it is expensive - period.?
Thx.

@90:

It was Kivu I meant, the methane content of Nyos is to low to make it ever profitable.

Nah, Mount Fako is not especially dangerous, it has pretty much not killed anyone in the last hundred years due to it's eruptions (directly at least). More people die due to running uphill of it than from the lava runs (most recently in 99).

But what I consider dangerous with geothermal plants is that noone knows what happens if you drill into the magma chamber, hollow out some 50 000 kubic metres ontop of it and then pump down many kubic metres of water under high preasure per second to produce steam for the turbines. And that is what I call the Kowabunga-version of Krafla.
What happens when you more or less rapid-cool a volcanos innards in an explosive H2O-process? It is estimated to produce a continous 3 magnitude quake for years...

You gotta low Africa sometimes, that volcano is multinamed. Mongo ma Ndemi means Mountain of Greatness, Have no clue what Mount Fako means, and Mount Cameroon is pretty easy to get:)

@Carl

Nah... that's just the size of the file. I took a shot at slicing down the area of interest to about a 1 degree x 1 degree area centered on Etna, with hard limits on the boundary. The idea being that when I threw the humongous terrain set at it the stuff outside the box would fall away, and I would still be able to use my computer.

Didn't work.

After about 10 to 20 minutes I had the display, but couldn't do anything with it, like slew or skew. Plan 2 is to extract the data from the orig file by taking only the terrain info for the slice, and not having the graphics program do the filtering.

As for the Cray idea... No. But I do have an Alpha 21164 based system (Alpha PC) sitting in the corner... mainly for nostalgia sake. For it's time, it could blow the doors off of comparable systems. Too bad DEC didn't know how to stay in business. As a trivia note, the AMD64 chip bus used the same signal set as those old Alpha chips... seems that part of the design team went to AMD after Compaq/HP let the Alpha die on the vine.

Interesting article on a "Double-Quake" causing the Samoan Tsunami last September:
http://www.google.com/hostednews/ap/article/ALeqM5gNdPEOVLhkBd6eKsJW23c…

#93 @Doug C.
Interesting, indeed. And I suggest further reading of the other three links at the bottom of the page.
According to the articles, the discoveries were made by two different groups of scientists.
I looked for the EQ information at USGA and it says:"On the basis of currently available location and fault mechanism information, we infer that the September 29 earthquake occurred as a normal fault rupture on or near the outer rise of the subducting Pacific plate."
But now they found out that there were two simultaneous megathrust events, both 7.8 M, triggered by the first 8.1 "normal" jolt. They hit in a lapse of two minutes, on the overriding Australian plate, which displaced the island of Niuatoputapu 400 mm to the East, which wouldn't have happened from the first 8.1 jolt on the subducting slab.
Maybe seismologists should review big events like this because now they have more instruments to accurately plot the data (we saw multiple quakes occurring on subducting plates recently, in Moro Golf Mindanao).
Thanks for posting.

#94 Sorry, USGS

Hi everyone!

What is that billowing on the right side of the hvolsvelli cam?

http://live.mila.is/english/eyjafjallajokull-fra-hvolsvelli/

Hi, Your Highness. Good to hear from you.
I can't see what you mean, but maybe because it's already dark.

Hello Sir Renato! Nice to see you again. :)

I should have taken a screenshot of it. It was quite high (a good couple thousand feet) on the far right side of the screen. It's still there, but barely faint in the poor light now.

I'll watch for it again once the sun comes up. Have there been any anomalies lately? I haven't been keeping up lately. *sigh*

@Your Highness: *Sigh* If it was there, it's gone by now. There's a reflective glow that disturbs vision.
As for Iceland, except for some alterations on tremor plots mentioned by Jón FrÃmann's observations under Katla, suggesting "the beginning of the beginning of a possible future eruption", everything is quiet. Lady E is taking a looong nap, puffing a bit every now and then, but she has already been declared dormant.

For now I'm trying to understand Etna, with the outstanding orientation of Boris. It's been very exciting and I'm looking forward to part 3.
I should be doing my work now, but these volcanoes don't let me. :)

@Princess Frito
I was checking at Jón's Helicorders and I noticed very high winds now, showing on tremor plots. I don't know if they are related to your "billowing"

@Renato,

What I found strange was that there were low clouds blowing almost sideways where we normally see it them, but this huge thing on the right was going straight up.

I'll monitor the situation at daybreak :)

Does this tell you anything?

http://hraun.vedur.is/ja/Katla2009/stodvaplott.html

#101 @Your Highness:
One thing I learned from Lady E experience: cloud formations can be the most tricking thing you can imagine, specially over a volcano. Since I started lurking at this one I saw ashclouds and steam plumes everywhere. In one occasion I was at the university looking at the Sugar Loaf (yes, I have a beautiful view of it from my window), and then I caught myself gazing at an enormous "ashcloud" venting from its summit - it looked so perfectly volcanic! From then on I stopped being suspicious about this kind of "billowing", although sometimes Eyjaf grants us with some pretty high steam plumes.
As for the tremor graphs, I confess, I don't see anything abnormal; every time stronger winds blow , graphs go up. ;)

#101 What I have noticed today, was a cluster of pretty strong quakes under Vatnajökull, at different depths.
http://en.vedur.is/earthquakes-and-volcanism/earthquakes/vatnajokull/#v…
It seems weird, because quakes in Iceland had a significant decrease for the past 72 hs. There were a couple very shallow jolts under Mýrdalsjökull, but they're supposedly caused by ice melting.

A 4.7 M quake hit at REYKJANES RIDGE
2010/08/19 06:57:30 / 54.086 N 35.120 W/ 10.0 km deep - USGS

Other 4 quakes under Vatnajökull!

19.08.201008:33:5464.737-17.2725.4 km2.076.365.7 km SSW of Kistufell

19.08.201008:32:3364.742-17.2443.6 km3.090.034.6 km SSW of Kistufell

19.08.201008:31:1164.741-17.2662.0 km3.890.085.2 km SSW of Kistufell

19.08.201008:23:0164.745-17.2523.3 km2.690.054.5 km SSW of Kistufell

Big quakes at Vatnajökull...

Thursday
19.08.2010 09:04:48 64.762 -17.229 3.5 km 2.0 90.01 2.3 km SSW of Kistufell
Thursday
19.08.2010 08:56:28 64.740 -17.217 2.5 km 2.3 90.02 4.6 km S of Kistufell
Thursday
19.08.2010 08:54:38 64.749 -17.250 3.8 km 2.7 90.06 4.0 km SSW of Kistufell

Thursday
19.08.201009:15:4564.746-17.2705.5 km1.664.724.8 km SW of Kistufell

Wow, this area is quite active at the moment.

Yes quite active. Just tectonic activity though since there are no volcanoes in that area (as far as i know). The closest one beein bardarbunga but thats a bit to the south-west right?

I don't know if it is above normality, but it seems to me it is. Bárðarbunga is a huge volcano, its crater is filled with a 700 m layer of ice. Any idea of tremor plots?
Stærstu skjálftar sÃðustu 48 klst (EQs in the last 48 hs)

3,119. ágú. 08:31:11Yfirfarinn5,2 km SV af Kistufelli
3,019. ágú. 08:32:3390,04,6 km SSV af Kistufelli
2,718. ágú. 20:39:2390,17,4 km ANA af Hamrinum
2,419. ágú. 08:23:01Yfirfarinn4,3 km SSV af Kistufelli
2,318. ágú. 03:12:25Yfirfarinn11,4 km ANA af Bárðarbungu
2,018. ágú. 23:34:4590,02,6 km S af Kistufelli

Wait...Correction.

The Trollagigar fissure runs NE from Bardarbunga up to Askja..But still probably just tectonic tremors. ;)

I must go now. I don't think it's merely tectonic this time. Wish I could have any news of tremors. Have you all a good day!

I do think too, that this seismic activity is not only tectonic. The Barbadunga Volcanic System extends over a really large area. I do not know it for sure, but isn't the Lakagigar fissure part of the barbadunga volcanic system?

also the quakes seem to build a line, like a fissure; any comments on that?

@113 Stefan, This paper is a really long one but it explains Iceland's Faults in great detail.

http://www.vedur.is/media/vedurstofan/utgafa/skyrslur/2010/2010_003rs.p…

And this link explains the Southwest part of the Island for both earthquakes and volcano mapping.

http://www.vatn.is/media/vedurstofan/utgafa/rit_200521_subsurfacefault…

Enjoy.

Daniel, #109: I am not sure, what the reason is, so far I haven't heard anything on the news about it. Iy you look on the earthquake map, than you will see, that this area has a number of old volcanoes...
The quakes happen on the edge of the glacier and are quite diverse in depth.

Dyngjujokull satellite view(close to quake activity)

www.satelliteviews.net/cgi-bin/w.cgi?c=ic&UF=-2643314&UN=-3650988&DG=GL…

@all interested in Bardarbunga and quakes there:

Just so that everyone will have a reference.
The series of quakes have an average point 180 metres north of the rim of Bardarbunga and about 200 metres to the west.
That is by far close enough to point to a flank eruption coming up.

But, if we are to believe the Global Volcanism Program and it's coordinates it is actually a part of Askja that is showing activity. The southwestern most parts of Askja are:
KISTUFELLSGJOSKA Fissure vent 64.93°N 17.22°W
KISTUFELLSHRAUN Crater Row 64.8°N 17.18°W
http://www.volcano.si.edu/world/volcano.cfm?vnum=1703-06=&volpage=synsub

If one cross-references those 2 to the quakelist you see that the coordinates matches pretty well.
So my question here is what in the name of the Holy Macaroni is the difference between Bardarbunga and Aksja Volcanic System? Apparantly 200 metres the birdway...

Be that as it may, it doesn't really matter if it is Aksja or if it is Bardarbunga rocking, either of them would be baaaaad news (but terribly exiting) if they started a large eruption. But let me remind you that it is more likely with a VEI-Mouse than an VEI-Megalodon, if it even erupts. It might be just some tectonic settlement or another instance of those pesky Icelandic Gola-dancers.

Strange seismic readings from Utah, Zion National Park is located at the south-west corner of Utah, I was trying to see which monitoring stations showed activity when the big quakes were happening in the Marianas Island region when I noticed strange readings. These readings happen everyday at around the same time and they are no small either, starting at 9:00pm going all the way to 9:00am, on this link look at the earlier dates located just above the graph and let me know what you think.

http://www.quake.utah.edu/helicorder/znpu_webi.htm

A swarm of deep earthquakes ranging 1.4 to 3.1 has hit the northern part of Vatnajökull. See http://en.vedur.is/earthquakes-and-volcanism/earthquakes/vatnajokull/

@118:

R.Hurst, I would guess it is mining related. The timings kind of suggest that it is the night blast phaze that is visible on the graphs and that the silent day periods are when the out-loading is done.
Many mines does the blasting during the night due to the blasting requiring very few personal (cost-effective), and of course you want a minimum of personel down there when blasting. Mine blasts create quite nice "quakes".
Just my few cents.

Does anyone have any GPS data from the area where the EQ´s hit today? Would be interesting to see.

Hmm...This was interesting. Look at the vertical component at the bottom.

http://hraun.vedur.is/ja/englishweb/gps/cts/vat.html

It would seem that just in a few days the GFUM station and SKRO station has been elevated alot!!

GFUM is Grimsvotn i would guess and SKRO is Skrokkaldar?

@122:

Thank's Daniel for re-finding the gps-plot:)
I've noted before that there is a long ongoing trend of rising at the GFUM and SKRO. They have been rising on average 17 centimetres in 7 years. Or in GFUMs case 22,5cm in 4,5 years. If we then assume that HOFN is symptomatic of the local landrise due to iceage icewall rebound and the normal magmatic up-push of Iceland due to plume we get that we should deduct about a centimeter per year.

Then we get something spectacular at GFUM. It has risen 18 centimetres above average in 4,5 years, or more to the point, 4,5 centimetres per year after normalisation. Whow!
Then we go to GFUM north movement. And that is minus 20cm, after renormalisation that would be 19/4,5 = 4.2 cm a year.
East-component is nominal compared to HOFN, but that is expexted due to normal rifting.

Now we just need a tremorplot for the area and we are good to go. I know I found one once but I seem not to be able to refind it. bad me for not book-marking it as a favourite.

There is some evidence that the Dyngjujokull fissure system is associated with Grimsvotn.

You can find all the tremor stations here: http://hraun.vedur.is/ja/englishweb/tremor.html
Unfortunately the last data from the nearest station Grimsfjall is from August 12.

The swarm is continuing... Which volcano does the location of quakes correspond to? Bárðarbunga?

@ 126-Jack,

Researching that area this morning I came away with that there is objecting opinion to which the Dyngjujokull fissure belongs to. There is evidence of it venting Grimsvotn(some cool satellite pics showing such) Bárðarbunga and also Kverkfjöll volcano.

I am likin the Grimsvotn angle though....just my opinion.

Vatnajökull Area - 8/17/10 to Present

View North

http://i38.tinypic.com/2dhtobq.png

View East

http://i35.tinypic.com/walxmb.png

Bárðarbunga (64.64 -17.56) and GrÃmsvötn (64.42 -17.33) are two of the major volcanoes in the area, though it really doesn't matter that much. When activity occurs, the system has been known to shoot a sill/dike off to the most convenient volcano to commence an eruption. Bárðarbunga is closest to the current activity.

From a paper on an odd 1996 quake that pointed to a possible dual layer magma chamber.

"A sequence of earthquakes commenced 29 September starting with a magnitude 5.6 earthquake in the Bárdarbunga volcano.

Similar earthquakes had occurred in this area previously. Ten earthquakes clustered around the Bárdarbunga caldera are reported in the Harvard Centroid Moment Tensor catalog for the period 1976â1996 (Nettles and Ekström, 1998). However, this time the event was followed by a swarm of small earthquakes that migrated toward a neighboring volcano, GrÃmsvötn, and culminated in a subglacial volcanic eruption"

TkalÄiÄ, Dreger, Foulger, and Julian. "The Puzzle of the 1996 Bárdarbunga, Iceland, Earthquake: No Volumetric Component in the Source Mechanism". Bulletin of the Seismological Society of America, Vol. 99, No. 5, pp. 3077â3085, October 2009.

rses.anu.edu.au/~hrvoje/Tkalcic_etal_BSSA2009.pdf

Jon Frimman, where are you?!

I have just read through the posts for today, Aug 19, and the quake activity in Iceland is interesting. I will keep checking back to see what is going on.

@ R. Hurst #118 and Carl #120, I checked the depths of the quakes in Utah and I think they are too deep to be mining related. There is a lot of mining activity in Nevada and when there are blasts, the depths are posted as 0.0 km or miles. I doubt there is a mine in Utah that is 4 miles deep. As for the graph, it is possible it was picking up the large quakes over in the Marianas area. I could be wrong on this because I didn't take a look at the time element.

One thing I have noticed in Nevada is that some of the blasts can generate a 3.0 seizmic wave and sometimes the blasts probably can set off a real quake if the fault near the mine is ready to move.

My DH one time was with a crew that was operating a thumper truck (they don't use these anymore, but in case there is someone who doesn't know what it is, they are a truck that thumps the ground with a "hammer" that is full of mercury) in S CA and they were looking for oil. They let it go and were in the process of gathering the data and setting up the truck again when they were swarmed with geologists and seizmologists who wanted to know what the blip they were doing. They asked them what they were going to do next and they said they were going to set it off again. The geologists told them they were not! Turns out they set that thump right on top of the Garlock fault and if they did it again, it could trigger a major quake! Needless to say, they packed up and left. It is one of those things you can laugh about now, but at the time, it was definitely NOT funny.

@Diane N CA

Those geologists didn't happen to be covered with coffee were they? I can imagine someone sitting there sipping coffee and having the gear go nuts when the truck started it thumping...

@Diane N CA

Thanks for taking a look at the data, what got me thinking was during the quiet times in the Mariana's area they were still happening during the same time periods. Another puzzling thing that I found by looking at the different stations is that they all don't pick up the quakes, only a certain few do, even stations that are pretty close have different data.

@Lurking, I was thinking it might have been more on the back side than the front. LOL

@R.Hurst, that is interesting that the data looks different. There can be a number of reasons for that and I don't have answers. It will be something to watch to see if they get any more in that area of Utah. I wish we had a couple of seizmologists posting once in a while here. It would sure help.

Does anyone know if there is any public webcams covering the northwest vatnajökull area?

Utah, view north. Latitude limits 36°N to 37°N

http://i37.tinypic.com/2cmkh2r.png

"Utak" ... groan.

And it keeps on rumbling...Another one +3 mag...

Thursday
19.08.201017:32:4864.740-17.2402.9 km3.190.074.8 km SSW of Kistufell

Map location
en.wikipedia.org/wiki/Kanarraville,_Utah

Utah shakes are probably geothermal field energy-plant related.

http://www.rasertech.com/geothermal/projects-in-development

(the map shows the only 3 GT projects active in UT at present)

@ People with more knowledge, i.e Boris, Jón, Passerby and so on....

What is your take on the activity on the NW side of Vatnajökull?

Is there something brewing volcano wise or just some restless plates having a hard time staying still?

Looking at the depth and location i would say that the bardarbunga, trollagigar fissure system beeing restless. And the GPS measurements would seem to support that.

http://hraun.vedur.is/ja/englishweb/gps/cts/vat.html

Caveat emptor ...

Askja is also known as Trolladyngja

And of the plants listed, they run 335 to 2133 meters depth.

There is the Newcastle area 18 miles NW of the quake centers. It's used for heating and greenhouses according to utah.gov.

http://geology.utah.gov/emp/geothermal/geothermal_use_utah.htm

Unless some one is going deep with a new facility, I don't think that's it.

My two cents regarding the recent GPS data as a layman.

Looking at the SKRO and GFUM stations since they are the closest ones and should be the ones most affected by any change at the area in question.

One thing that caught my eye is the trend at each "new year". If you look at the years its always a spike. Then it goes down for a month or so only to resume increasing/decreasing (depending on what component) after that. I assume, since there is alot if ice present, that this has to do with temperature shifts and that would only be natural since even a small change in average temp/day would have large impact on the icecap covering the area.

Anyway I was looking at the charts and this is what I came up with.

East component: Same annual pattern as I described without any deviation as far as I can tell except that GFUM has more movement/year than the other stations (13-18cm since 2006).

North component: Same here. The stations follow a predictable pattern while GFUM stands out with a large movement in a short period of time (almost 20cm since 2006) and during the last month a sharp increase in southern movement.

Vertical component: Now it gets interesting. Up until now the SKRO station has been somewhat similar to the other stations except GFUM. Now it joins in and shows a large inflation during the past month. 2-3 cm uplift on both SKRO and GFUM.

And what is also interesting the GFUM and SKRO stations has since 2004 followed the same annual pattern which I described earlier. But not this year. They both got the annual spike but have not dipped down in the same fashion as earlier. And they register a sharp rise!

Man I would love to have a webcam in that area...Any Icelandic with a 4x4 and an extra webcam up for a roadtrip? ;)

Roughly the same map as pointed to in my post [140], but with the Quake area and USGS listed fault lines for the area.

http://i36.tinypic.com/2s1ndbk.png

Ok now i know something has caught peoples interest at Vatnajökull.

Helicorder at Grimsfjall has been turned off for a while. but today they started it again!

http://hraun.vedur.is/ja/oroi/grf.gif

Ref my post [128]

Time series plot of that area verses depth.

http://i37.tinypic.com/x5yufc.png

Nothing to write home about, but there ya go.

#144 Good work, fellows. Now we should be some feeding back from the media, but I didn't find anything. But the quakes keep coming. They revised and removed many of them (including the earlier 3.8) from the list of the big ones.
IMO data
The largest earthquakes during the last 48 hours
SizeTime Quality Place
3.119th August 17:32:4890.14.8 km of SSV Kistufelli
3.019th August 08:31:11Reviewed5.2 km SW of Kistufelli
2.718th August 20:39:2390.1ANA 7.4 km of the hammer
2.619th August 14:30:1350.29.3 km of SA Herðubreiðarlindir
2.519th August 08:32:33Reviewed4.8 km of SSV Kistufelli
2.419th August 08:23:01Reviewed4.3 km of SSV Kistufelli

This is all I find from RUV news, and is still about ashes from Eyjaf:
Ash in the wood blocks fiskgengd
No salmon or trout is caught in a forest under Eyjafjöllum summer the river is more or less full of ashes. The river generally have caught one thousand salmon in summer.

Agreed wrt Vatnajokull area seimicity. If the IMO plots were busier, we get take interest.

Regarding Utah, I downloaded a technical blurb on the St. George Basin Geothermal area, containing the Hurricane fault system, mentioned in the USGS tech discussion of today's EQ, describing activity in the Intermountain Seismic Belt (ISB).

'The most prominent geologically young faults in southwestern Utah are the Hurricane and Sevier faults. The Hurricane fault forms the west-facing Hurricane Cliffs, which define the eastern edge of the Basin and Range within the ISB. Faults in the ISB in southern Utah locally show evidence of displacement younger than 10,000 years, but average recurrence intervals are generally longer than those on faults in the ISB in northern Utah'

The historical seismicity maps are busy (EQ since 1990), with the year's shake accumulation map showing approximately the same areal patterns.

To me, this looks like geothermal activity associated with the Hurricane fault system. *shrug* Not a biggie, either.

earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/uu08181252.php#summary

Well, we will have to wait and see. So far, it is too early to be sure. We need to see something at rise in Lurking's graphs and for now we have them mostly concentrated at a certain depth. Last week there was a 3+, but no cluster. And EQ activity under Vatna has been high most of the time. Nothing definitive.
But something is being cooked there. Matter of time.

To put things in context, here is a plot of Vatnajökull quakes back to 4/17.

There are three separate quake stacks here. The quakes from today line up in the two northern stacks. Do remember that these stacks are not necessarily indicative of moving magma, as many knowledgeable people have pointed out, the level of activity will likely be much higher than what is currently being seen.

http://i33.tinypic.com/2mpj6af.png

Fireman & family have just checked into the Hotel Ranga; in the unlikely event anything kicks- off in the next few days I'll provide live updates!

@Fireman:
Enjoy your staying and thanks for updates. I don't believe an eruption under Vatna is likely to happen any soon. After early magnitudes of the swarm were reviewed, quakes appear to be within normal levels.
Say hello to Lady E!

Hotel Ranga looks wonderful - www.hotelranga.is/ Hope you and your family have a fab time and - yes? - get to enjoy a mild Hekla eruption from the safety of the hotel room window.

PS. Any chance of a photo of Gigjökull in order to compare with your stunning pre-eruption one? ;)

@132 Diane N CA, Thank you for your response Diane, things are certainly strange in the Utah region, here is another seismograph for you, it's from the Madison River, Yellowstone monitoring station. There has been a lot of activity just around that site, all of the surrounding stations are really quiet and these are showing larger spikes, the interesting thing is that the station isn't sending any data for a lot of the time on different days, just look back at the earlier dates and compare, here is the graph from yesterday.

http://www.quake.utah.edu/helicorder/ymr_webi_2d.htm

@R. Hurst, you are welcome. Thank you for posting that Madison River helicorder. I checked several days and it has been rocking like crazy. I am not sure what is going on, but it must be picking up not only quake info, but maybe some other unrelated activity. This is why I wish a seizmologist would come here and explain the signals to us so we can at least get an idea of what we are looking at. We know from Jon's helicorder that wind can affect it and, depending how close to the road going though Madison Canyon the corder is, I would suppose there is the possibilty of semi activity creating some of the small seizmic waves.

Madison Canyon is an interesting place. The major quake that happened there in 1959 was devastating. The epicenter was actually out of the canyon, but the quake crated a major landslide in the canyon and ended up creating a lake and wiped out a town and camping area. They now charge you to go up and see the landslide up close and also there is a museum which probably has many pictures of the aftermath. At the time I was there, I didn't have time to check it out, but you can see the slide from the road.

A bit if info about that: my DH was there when the quake happened and he was only about half a mile from the slide. He at first thought he had really drank too much as he was awakened by the first bit of rocking of the car. Then he really got awake and realized it was a major quake and he was able to turn around and get back to West Yellowstone. That quake affected Old Faithful and make it less predictable that it used to be. If I rememeber right, it was a 7.5 or somehthing close to that.

A few times on the CA map there have been false posts of quakes and I would like to know what caused that, too. After a bit of checking things out, the quakes were removed from the map. That was a bit weird to see because when I first saw them, I really wondered what was going on, especially given where they were.

When Erik gets back, maybe he can get a seizmolgist to post some info about how they go about reading the graphs.

"Animal Planet" TV just starting a program on volcanoes of the Pacific Ocean (eastern US 2:05 p.m.)

@Diane N CA, I am here. But at current time I do not comment so a lot here unless there is something interesting going on.

There are regular earthquake swarms inside the Bárðarbunga volcano system (it is massive). However, the earthquake activity over the past few months in Bárðarbunga appears in some part be due to dike formation inside the volcano. That has not resulted in a volcano eruption at this time. But I am sure that one day that it is going to do that.

Given historic data (eruption 1996), a eruption in Bárðarbunga appears to start with a single big earthquake that is Mb5.0 or larger. So we are not going to see a lot of small earthquakes like that did happen in Eyjafjallajökull. This pattern also goes for GrÃmsfjöll volcano. But the earthquakes are smaller, with biggest earthquakes being around ML3.0 or lagers. But never lager then Mb5.0 so far. But that system can make Mb5.0 earthquakes, that is known from historical records.

This also goes for Katla volcano. So the only volcano that appears to be behave different is Eyjafjallajökull, with his many thousands of earthquakes before a eruption.

I am always watching for earthquakes and possibly of volcano activity. At the moment, things are quiet.

@Jón FrÃmann:
Thank you. We were all needing you to bring us back to our senses. I confess when I saw this big swarm starting with a 3.8, as it was first reported, I hurried to ring the bells.
Over time, we end by learning with them volcanoes that they have their own timing and pace, not ours.
In the meanwhile we are taking an enlightening summer vacation in Sicily. Tell us when, and we'll be rushing back.

As promised, here is my latest on Vatnajökull... but presented a little bit differently.

I took the boundaries for the chart/map located at en.vedur.is/earthquakes-and-volcanism/earthquakes/vatnajokull/ and applied them to the data, tossing out stuff that fell outside of there.

This is a time series plot of the quakes per 12 hour interval for the region during the time frame of 4/18/10 to 8/21/10. As you can see, it fully supports what the more knowledgeable people here have stated. (normal stuff going on)

http://i36.tinypic.com/a5hsv8.png

For the statistically minded of you, here is the distribution of that same batch of data:

http://i38.tinypic.com/30hx6hw.png

From that, it seems that (based on the time interval) that 1.6% of the time, there will be between 10 to 12 quakes in a 12 hour window. 80.5% of the time there will be less than 6 quakes per 12 hour interval. ( 27 + 31.7 + 21.8 )

Is it just me or is there a fair bit of activity around Bardarbunga in Iceland? While everyone is watching for a potential eruption from Katla, could it be Bardarbunga thats next to go?

Looking at the recent activity there seems to have been a good number of shallow mag 2 and almost mag 3 quakes:

http://en.vedur.is/earthquakes-and-volcanism/earthquakes/vatnajokull/#v…

@Lurking
You surely deserve the epithet of âmaster of chartsâ.
What would we amateurs do without them? Most information posted in this blog is readily converted into graphs, thanks to your relentless generosity to collaborate, regardless the expertise of those who rise the questions. They provide a clearer picture of figures and dimensions, making it easier to understand what otherwise would be too difficult to grasp, thus giving us the chance to keep up with the hard core discussions.
We can't thank you enough for that. Just tell us to stop, whenever you feel your brain is reaching âdegassing levelsâ.
As for recent swarms under Vatnajökull, we must rely on Jón's experience: he said that âthe earthquake activity over the past few months in Bárðarbunga appears in some part be due to dike formation inside the volcanoâ and that an eruption usually âstarts with a single big earthquake that is Mb 5.0 or largerâ.
You said that this last plot âfully supports what the more knowledgeable people here have stated. (normal stuff going on)â.
But what is to be considered ânormalâ? Should we take for granted that it is ânormalâ for a volcano to gather magma within its guts? After all, that's what they're supposed to do, isn't it? What your plot tells me is that, since April, we have more gaps in between the swarms, but each single swarm is getting bigger (more quakes per cluster). The August peak seemed to be special, because we had higher magnitude events, but how far we are from getting a 5+, we donât know.
I gathered some information of 5+ EQs around Vatna since the 70âs, but only a few of them led to an eruption, so, I donât know what to expect here.

MAGDATEDEPTH (km)

5,225/06/7433
5,229/12/7433
5,403/10/7533
5,227/07/7633
5,228/12/7710
5,422/06/7910
5,312/08/8010
5,330/09/8410
5,223/11/8610 * erup
5,303/02/8910
5,515/09/9010
5,122/05/935
5,705/05/948,6
5,526/09/9610 *erup.
5,629/09/9610 * erup.

And for those who missed it, a link to "The puzzle of the Bárðarbunga volcano"
http://rses.anu.edu.au/~hrvoje/Bardarbunga.html

@ Jon, #157

Thanks, Jon, for reporting about the quakes. I wanted to hear from you because I knew you would be able to tell us what is going on.

Let us know if there is any change in your thinking about the quake sequence. I am sure we will know if there is a big quake in Island and we will definitely need your input about it. After all, you are the one who knows more about what is happening there than we do. :-)

@Renato [162] -
That page is actually broken (an unclosed comment); you cannot view it on Firefox. IE displays it OK; does that mean that IE is, itself, broken?

@Kultsi:
I don't know what you mean by "broken". I got the link here, from our fellow bloggers, and I'm using Google Chrome, so I hope I didn't "break" any Internet rules. :)
There are two links to the downloadable pdf articles at the bottom of the page:
http://rses.anu.edu.au/~hrvoje/Tkalcic_etal_BSSA2009.pdf
http://rses.anu.edu.au/~hrvoje/Tkalcic_etal_AGU2009.pdf
Thanx for the info.
For what I could understand, the 5+ EQ caused the crater to colapse within the glacier causing a major eruption, but there seems to have been another weaker eruption before, causing a joküllhlaup.

@164: If you go to Dr. TkalÄiÄ home page and click on 'publications', you'll find the article listed and available for download.

rses.anu.edu.au/~hrvoje/Tkalcic_etal_BSSA2009.pdf

Thank-you for your plot Lurking. Your frequency graphic, however, shows the recent peak of activity to be atypical in occurrence number but not unlikely, in that the excursion and sampling period are brief. If 'something was up' we should see consecutive days of elevated activity.

We have already been through a discussion of probable mechanisms for these earthquakes.

Background reading.
Faulting mechanism of anomalous earthquakes near Bardarbunga Volcano, Iceland
www.seismology.harvard.edu/projects/unusEQ/Iceland/index.html

In fact, this discussion might be timely, as the proposed model of magmetic acitivty looks a bit like the crater/flank fissure cycle sequence at Etna.

Renato Rio's second link is to an wonderfully descriptive explanatory poster (used for technical presentations at annual science society meetings).

It's a hefty 54 MB download, be aware it may take a while, depending on your connection speed. Well worth the effort, though.

#165-166 @Passerby
Thank you for the useful hints.

@165 & al. -

By "broken" I mean the HTML code at the end of the link is not valid and conforming to the rules of HTML. The term I used is normal geek expression for malfunctioning site or program.

That does not mean that I could not or did not read the article and at least look at the two publications from linked from the site.

When I told y'all about the problem with the site, I hoped to alleviate the heartburn some might get from the site not opening correctly.

>I hoped to alleviate the heartburn some might get from the site not opening correctly.

Right. And that's why we replied and supplied the proper link and explanation of how to find it.

Alternatively, one can use Google or Yahoo search engines and type in the article title (which Renato thoughtfully supplied).

>IE displays it OK; does that mean that IE is, itself, broken?

No, it must mean that IE doesn't depend on comment closure to open it. Scripting tolerance for common errors, whatever.

For an alternate search method, one can go to this list of Hrvoje Tkalcic's publications and, if you have a Mac, use Command plus F and type in Bardarbunga in the "Find:" window. Many papers are downloadable in Acrobat.
http://rses.anu.edu.au/~hrvoje/publications.html

Um... does anyone happen to know if there was a fissure event in Iceland on the scale of Laki or Eldgjá in the early 6th century? I can't seem to find any research on Icelandic fissure events that are not those two. The target year I'm looking for is around 536.

Here is my logic. (if you call it that) 934, Eldgjá - big fissure event. 1783, Laki - big fissure event. A difference of 934 years. If the spreading rate of 20.3 +/- 0.2 mm/yr is reasonably constant, then the amount of accumulated spread would be 17.1 to 17.4 meters. Since 227 years have elapsed since then, the current accumulated spread would be on the order of 4.6 to 4.7 meters, or about 26.7% of the amount when Laki went up.

535-6 is a period of extreme weather events, complete with famine, rats, plagues and other stuff. Some have claimed it is associated with a volcano such as Krakatoa, or a comet. The period had a dust veil and some research have found increased sulfate deposits in ice cores. (Benjamin Franklin noted a dry fog in some of his documents... probably from the Laki event)

536 is about 398 years before the Eldgjá fissure event, and would have ment that 8 to 8.2 meters of spread had accumulated before Eldgjá.

The only semi-chronicler guy that may have been in the area would have been Saint Brendan, who allegedly sighted Jan Mayen during his voyages.

This is just a wild arsed idea. Any eruptive history of the fissure system between Katla and GrÃmsvötn/Bárðarbunga other than the 934 or 1783 events would be appreciated.

I am seeing pule activity on SIL station Lágu Hvolar (hvo). This appears to have started some time before the ML0.8 earthquake that happened few min ago (when I write this) close to place called Hábunga. This might be the first sign of volcano related activity in Katla. But at some time in the future, not at the moment. As there has not been the necessary high volume earthquake activity that follows eruptions in Katla.

I did mean pulse. This is what happens in late night typing.

#173-74 Thank you Jón. But try to get some sleep. If this activity develops into something any soon, then you see what late night means.

Lurking, good thinking! (#172) What about something such as Mt Rinjani, a volcano with a historical record going back no further than 1847, sports a caldera on the same order of magnitude as Tambora, but one for which the date is unknown? (Wiki, however, says it's thought to have occurred in the 13th Century).
//www.volcano.si.edu/world/volcano.cfm?vnum=0604-03=

IIRC, one of the reports about the 536 AD phenomenae you refer to(?) is from Rome. In that case, the jet stream divide at about lat 50N would indicate that the source would most likely be below that latitude, so a very large, tentatively or undated eruption in Kamtchatka or Indonesia ought to be a better candidate than Iceland or Alaska?

@Lurking (#172) Trölladyngja? //os.is/gogn/unu-gtp-report/UNU-GTP-1986-04.pdf page 7 gives a reference (Orkustofnun 1986) which dates the most recent period of activity as "1000-1500 years old", ie your date falls within this period. However, reading on, it doesn't seem to be large enough to fit the bill.

still on Iceland, BBC Science/Environment has a new little piece on Eyjafjallajökull with a video..
www.bbc.co.uk/news/world-europe-11039747

#178 @BirdseyeUSA:
Thank you for the post. I wish I could go visit the site. But it is sad to see how hard hit were the people living nearby. Hope Katla will spare them when it blows.

Not very good news for those living in California:
"Big Quakes More Frequent Than Thought on San Andreas Fault, Research Shows" (From Science Daily)
http://www.sciencedaily.com/releases/2010/08/100820145303.htm
Dark clouds in horizon? Hope not. But better warn in advance. I don't feel comfortable, even living far away from CA, with the amount of quakes we see there everyday. So, please, my friends: take good care of yourselves/properties.

@172, Lurking, this page explains the dust veil as due to Western Hemisphere volcanic activity: http://www.eh-resources.org/timeline/timeline_me.html
The journal article footnoted is password protected, though.

This forum page (regarding Scandinavia around 500 AD) from 2007 has clues in its citations (and if it's still active, posters might address your specific question).
http://community.livejournal.com/little_details/1701856.html

@181 Jane, thanks for the great reference. I've been looking for something like this for years. Huzzah ;)

@Jane

Interesting. (I managed to find the reference in the article on Scripd)

In Larsen et al, they list the 536 event as showing up in Greenland's core with the SO2 spike at 533/534 ± 2, and in Antarctica's SO2 spike at 542 ± 17. That's a difference of between 10 to 28 years.

For the 1815 Tambora event, both Greenland and Antarctica spike in 1816 (±1 for Antarctica).

To me, that would seem to indicate that whatever source there is for the spike would not be located in the tropics, or in the Southern hemisphere since the signal simultaneous, and points to a northern source.

I'm guessing that either the fissure event has gone un-noticed in the geological record in Iceland, or it was buried in later flows... probably Laki or Eldgjá since it would still be discoverable if it were anywhere else on the island. Of course, there is also the possibility it could be off the northern or southern shores.

Note: "the signal simultaneous"

Should read: "the signal is not simultaneous"

Still mulling this over.

[183] does not rule out another Northern Hemisphere location, but the scope of the event seems to be on a par with the two known Icelandic events. It's pretty hard to hide that much lava. It's possible that it's in a remote, under explored region (Kamchatka?) or it's buried under something.

Katla erupted in this time period.

Either of those two large SO2 signal events could have been Rabaul, VEI-6.

The Cascades and Mexico volcanic provinces were quite active.

When I posted #83, I forgot to tell y'all about one of the strange things in the middle of some serpentine. It is a small pocket of blue shist. I saw that some time ago when I was driving down that particular road and I decided to get a sample of it. It is brittle and rather soft at the same time. In other words, you have to handle it carefully or it will break-up in you hand. It is a very pastel blue-gray color and is beautiful.

I have not been able to get out to do more investigating what it around here, but I will in time. Right now I am very busy with other stuff that needs taking care of. I certainly will be letting you know what else I find.

BTW, this area is known for its crystaline gold and the purity of the gold. There has been some .85 to .92 fine gold found. I have learned that if you know your gold, you can tell where a person found it even if they don't tell you. I am not that savvy. :-)

Lurking, does the nature/signature of the Greenland and/or Antartic SO2 spikes rule out every other type of explanation other than a large fissure eruption such as the Laki/Eldgja ones? Another divergent thought - how about the fissure being covered by a really substantial glacier? In 1500 years, a fast-moving glacier such as the Jakobshavn Isbræ on Greenland could theoretically have moved as much as 10,000 miles (based on the given rate of 20-30m per day) or 1,000 miles the case of the Antartic Byrd Glacier (2-3m per day). Even if this is peak movement, an annual average of 11 metres would result in 10+ miles over 1500 years, in other words, be enough to cover even a very large effusion from our prying eyes.

@Henrick.

No, it doesn't rule out any other source. IF it was an event in the Laki/Eldgja system, then that would mean that the 934 event would have only had time to accumulate 7 to 7.2 meters of spread. Provided that all of the stress/spread had been filled by this hypothetical event. That tends to run counter to my idea, but if it's true, then that would mean that the average Laki/Eldgja style event happens every 623 years.

The next "due" one would be 2406 CE. These two (very dodgy) samples would lean towards an SD of 318 years, placing 2010 (today) out in 2 SD land.

As Passerby points out, Rabul had a VEI-6 event in 540 AD ± 100 years, so other sources are quite possible. However, from it's tropical location, I would think that it would make an Greenland and Antarctic SO2 spike more closely aligned in time, similar to the Tambora SO2 spikes.

Not bad for Sunday musing. Beats drinking a beer.

Grr....

Eraser time again.

"Henrik" vice "Henrick"

and "8 to 8.2" vice "7 to 7.2"

Hehe! You may call me Henrick - provided I can call you Lurcking of course ;). Still doesn't change the fact that collectively, we haven't found the explanation for the "Red Skies of Rome" in 535 AD, which btw sounds like something Doris Lessing might have written. Passerby's Rabaul caldera forming eruption of 540AD (+/-100yrs) is too close to ignore as a likely, if not the most likely, source of the Greenland and Antartic SO2 spikes.

According to http://www.volcano.si.edu/world/volcano.cfm?vnum=0803-122&volpage=erupt the Haruna eruption in Japan (VEI-5) is dated to 550 ±30 days via "Anthropology". Larsen et al roughly equate this to the SO2 spike at 529, but only indicate that the deposition patterns mean a higher latitude event.

Regarding the 536 event:

"The Greenland ice core data suggests that the eruption
associated with the 536 dust veil caused 40% more
SO4 deposition than the Tambora eruption, while the
Antarctic ice core data suggest that the eruption had a
deposition some 15% smaller than Tambora. However, the
uncertainty of the Antarctic SO4 deposition estimates are
too large to draw any firm conclusions."

"New ice core evidence for a volcanic cause of the A.D. 536 dust veil" Larsen et al
GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L04708, doi:10.1029/2007GL032450, 2008

At least one author (Robert Key??) went to great lengths and IMO stretched the geological facts to breaking point to 'prove' that the 535 crisis was caused by Krakatau. I'm inclined to agree with Passerby that Rabaul is a better candidate, but there are others which have been put forward, including Churchill (Alaska). Karkar in the SW Pacific had a caldera-collapse about that time too. And it's not impossible that two unrelated major eruptions close to each other in time might have increased the severity of the problem. Unlikely, yes, but it has only needed to happen once..and as recently as 1993 there was a VEI 6 (Pinatubo) and a VEI 5 (Hudson) just three months apart

Well, looking at the graphs in that paper, there are two SO2 events in that time span. One in 529 equated to a higher northern latitude by the author, and the 533/534 (the one in question) equated to the "dust veil." I'm a bit perplexed at the conclusion considering the statement that I quoted above (which seems to contradict the conclusion)... but I'm just a guy sitting in Florida enjoying the thunderstorms.

"Nibblin on sponge cake
Watchin the sun bake
All of those tourists covered with oil..."

(Should be BP's new theme song)

"St. Brendan was an Irish monk who according to the Navigatio Santi Brendani Abatis built a boat made from cow rawhide and sailed from Ireland to North America around 530 AD."

...

"In his 9th chapter, Island of Smiths, Severin describes the experience of approaching Iceland from the east. According to the Navigatio, Trolls would sit on the cliff faces of Iceland throwing fiery balls of fire at St. Brendan and his monks. (Severin, 162-163) ... Severin concludes that due to his experience it is very possible that the "Irish navigators may have seen the volcanos of Iceland, which lie exactly on the Stepping Stone Route to North America, and could provide exactly the scene found in the Naigatio.â (Severin, 163)"

https://thevikingworld.pbworks.com/The-Early-Settlement-and-Trade-of-Ic…

The latin machine translation I found of Navigatio Santi Brendani Abatis makes the Google mangling of Icelandic look like prose.

Trolls throwing fiery balls of fire some time after 530 AD.

Hmm..

Thanks for the interesting link, Lurking! To diverge, the article on thevikingworld says "There are also other accounts that suggest that people knew of the icy island in the middle of the North Atlantic Ocean before the major settling in the 9th century."

Now, look up "Red Paint People"! //en.wikipedia.org/wiki/Red_Paint_People

Consider these two facts: a) the art of making boats (out of hide or other materials) is considerably older than a thousand years, and b) graves that correspond in every detail with ones discovered and described on the West Coast of the Atlantic have been found on the European Atlantic coast as well.

@Henrick [196]

I have always been a fan of the European origin of the Clovis people. Though first discovered in Clovis NM, the majority of Clovis sites are found in and around the tidewater area of the Chesapeake Bay. (East Coast of US)

Clovis points bear a striking similarity to the points used in the Solutrean culture of France. The major difference being in the fluting on the rear of the points. Archaeological finds of the right age near the North American entry point from the Bearing Sea (bridge) are very dissimilar.

My take is that Clovis culture, or what was left of them following the Younger Dryas, integrated or melded into the arrivals from the North West... or the technology was found and adopted.

The swarm at Vatnajökull continues... It seems (at least to me), that the average depth is slowly rising towards surface, and the average spread in depths is narrowing. Are my eyes just lying? It would be nice to see an update to Lurking's figures, especially the one including earlier (e.g. April) swarms.

There is a new Swarm of Earthquakes beneath Barbadunga, this time they are closer to the Surface.

And a new Magnitude 3.4 Quake quite close to the Surface, Still only tectonic nature?

Monday
23.08.201006:19:0064.705-17.2810.7 km3.490.19.1 km SSW of Kistufell
Monday
23.08.201006:13:2564.694-17.3003.6 km1.990.0110.6 km SSW of Kistufell
Monday
23.08.201006:11:2264.709-17.2642.8 km2.162.338.4 km SSW of Kistufell
Monday
23.08.201006:10:5264.700-17.2811.5 km2.790.089.6 km SSW of Kistufell
Monday
23.08.201005:52:0264.699-17.3105.6 km1.369.8110.3 km SSW of Kistufell
Monday
23.08.201005:45:4064.675-17.3815.8 km1.686.38.0 km ENE of Bárðarbunga
Monday
23.08.201004:50:5964.677-17.3014.2 km1.369.3711.5 km ENE of Bárðarbunga

I meant to say, to Lurking's depth-vs-time figure.

@Stefan #199

I just saw the swar as well and was about to post it. :)

It would really be nice to have a proffessional opinion on the activity at bardarbunga. Seems to alot of activity on the NE fissuresystem. Is it tectonic or magmatic?

Some info about the Eruption in Grimsvötn, maybe this can give some perspective. but i would love to read from the professionals.

http://hraun.vedur.is/ja/englishweb/eruption_grimsvotn.html

#199 #200 #201 I suggest you guys read through all posts on this thread. Lurking has already made plots dating back from April, maybe he could have an update for the most recent events. Jón FrÃmann says there could be a dike intrusion, but an eruption should only come after a 5+ EQ, so these massive swarms are a bit of a commonplace at the location. There are also links explaining the relations of sub-glacial eruptions under Bárðarbunga and EQ activity.

@203 ive read trough all the posts and i stand by my comment, after all, the link about the grimsvötn eruptions does not mention a 5+ quake that startet the eruption. but with time we get wiser and will see if there is truth to this.

Just take a look on the tremor plotts, and my conclusion so far is, that something is definitely going on, there are massiv spikes and an increase in four of the nearest station to barbadunga:

http://hraun.vedur.is/ja/oroi/vat.gif
http://hraun.vedur.is/ja/oroi/grf.gif
http://hraun.vedur.is/ja/oroi/skr.gif
http://hraun.vedur.is/ja/oroi/kal.gif

i cant take my eyes of the plotts and the seismicity-map of Vatnajökull

#202 Thank you for the link, it tells a slightly different story from that of previous explanations. Take a look from post #103 to #166

Well.. no trendline, I used a scatter plot to make these. You'll have to eyeball it. The scatter plot was used to encode the magnitude of the quakes by color. I think you might like it.

Bounding Box of 64°N - 65.3°N / 16°W - 18.5°W. Holds both Bárðarbunga and Grimsvötn.

Plot 1 - 4/17/10 to 8/23/10. Depth vs Time

http://i36.tinypic.com/2ezqr2c.png

Plot 2 - 8/1/10 to 8/23/10. Depth vs Time

http://i35.tinypic.com/29fqfxh.png

Plot 3 you'll have to cun-n-paste into a browser, If I link it the forum software will jump on me.

8/14/10 to 8/23/10. Depth vs Time

i35.tinypic.com/15dntax.png

Yes the links and posts from previous discussions do explain alot. But at the same time the report on the Grimsvötn eruption seems to be following events we are seeing now.

So..Please any proffessional that has an opinion? A bit torn between the two theories here. :-)

@ Lurking

Tanks for the plotts; could you do one of your 3d like plotts, so that we could se in which area the quakes are located.

i think you made one with an overlayed map, and x,y,z axis.

if its to much work, it would also be ok.

but thanks again for your input, i really aprechiate that!

Still i cant help thinking about the displacement.

http://hraun.vedur.is/ja/englishweb/gps/cts/vat.html
20cm East
20cm South
20cm+ Vertical

And all this is since 2006. The South component has taken a turn and increase southward movement just in the last month(s).

Umm.... okay. But I got to go now.

Perspective

http://i37.tinypic.com/2laue83.png

View North

http://i38.tinypic.com/35iqi2u.png

View East

i38.tinypic.com/29pdhtw.png

Plan View

i34.tinypic.com/24mxmae.png

Cun-n-paste on the last two.

Same plot box as the time series in my last... but these only have 8/1/10 to 8/23/10 quakes.

I think many pros are fed up with media mongering about Katla. So I think they are very reluctant "promising" anything until it seems inevitable. I'd probably do the same, especially on a public blog post.

#210 @Jack: I agree. It could be normal and "deceiving", yet, it could be not.
@Daniel_swe: I'm afraid we'll have to wait. So far there weren't any clues from the media or elsewhere. What I can tell from what I read, is that jokülhlaups from Vatna happened before without any advise and some eruptions are marked with a big question mark under brackets. If a jokülhlaup occurs, we may even get another "question marked eruption". And we shouldn't expect fireworks as those we've seen on Eyjaf. This is my humble opinion. Now, the 3.6 event has been downgraded to 3.0. They'll probably say it is within normality. I'll be waiting here for more news.

strange volcano at such cold place...shocked to see that..guide me something about that.

There are some odd GPS reading at GPS station THEY and SOHO, HVOL has not updated.

There appears to be a lot of movement going on at the moment. That can be seen by the long lines on the GPS plot, the the main center the red dot. I am unsure what is going on, but this might be magma injection at Katla, as the GPS signal is clearly not coming from Eyjafjallajökull I think. If it is coming from Eyfjallajökull, then it is expanding into different direction then before.

The earthquakes at Vatnajökull are so far just tectonic ones.

Thank you Jón..For bringing us down to earth. :-)
Actually it is a good thing that bardarbunga is quiet. As one official said a while back:

likelihood of an eruption in the main volcanic field under Bárðarbunga is there for not considered very likely, but if it were to happen it could be an eruption of immense proportions that could once again make the one we have seen seem like a firecracker.

Weird cloud over Lady E (Hvolsvöllur cam only) that does not move with the rest and seems to have been stationary over the peak for at least the last 30 mins. Plain weird...

I was looking at other GPS stations, and it looks like a error in the GPS plot for today. But tomorrow should bring more accurate numbers in the case of error today.

In genereal I agree with the far more knowledgeable Jón.
I just want to point out a couple of things.
It is not entirely clear if it is Bardarbunga or the Askja Fisure system. Actually the coordinates support the latter. But it could be a dyke from Bardarbunga to, it is just a few hundred metres between them you know.

The coordinates for the south-west endpoint of Askja fisure system with known eruptions:
KISTUFELLSGJOSKA Fissure vent 64.93°N 17.22°W
KISTUFELLSHRAUN Crater Row 64.8°N 17.18°W

So there is actually a rather low probabillity for the need of an M5+ quake to start it if it is not Bardarbunga. And also I would like to point out that the N-value of the M5+ suposition is rather low, only 3 known eruptions of Bardarbunga has started that way as far as I can understand.

That said, I thank Jón for his probably absolutly correct statement about the not imminent eruption of the Bardarbunga dyke and that everything is just tectonic activity.

Are strain measurements available live for Eyja/Katla, like tremor measurements?

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