Anatahan

Our tour of the Marianas begins SW of Guam. In this area the volcanoes are submerged and make up a region known as the Southern Seamount Province. Our first stop is Tracey Seamount, which lies 30 km west of Guam. Tracey is a ~2 km tall cone and volume of ~45 km3 It is one of the smaller volcanoes in the Mariana arc; Pagan, contains about 2200 km3 of material (Bloomer et al., 1989). It has a sector collapse on its western flank and resembles a submarine Mt. St. Helens. It was investigated by the ROV Hyper-Dolphin from the R/V Natsushima in Feb. 2009, which revealed that the cone is map up of…

This week I welcome Dr. Ed Kohut as a guest blogger here on Eruptions (while I am off in the Sierras doing some field work). I've known Ed for 10 years now - we were both graduate students in igneous petrology at Oregon State University - and we are both Massachusetts natives. Ed was in the Coast Guard before getting degrees at University of Rhode Island and Boston University before heading of to Oregon State for a Ph.D., where he worked on melt inclusions in minerals. One of his major research areas is magmatism in the Mariana Islands and he was nice enough to put together a look at the…

Sarigan Island in the northern Mariana Islands. An undersea eruption appears to be underway south of the island. Thanks to the watchful eye of Eruptions readers, we had an inkling of this eruption the other day, but now we have confirmation that an undersea eruption is underway in the northern Mariana Islands. The exact volcano erupting is unknown, but it appears to be between Anatahan and Sarigan (see below) - both active volcanoes in the Marianas - at a depth of 300 meters. The eruption has been described by the USGS as hot water vapor and an ash plume that might have reached as high as 12…