Observing the historic eruption of northern Mariana Islands volcano

Abstract

Anatahan volcano erupted for the first time in recorded history at about 7:30 GMT on 10 May 2003, covering the island of Anatahan, in the Commonwealth of the Northern Mariana Islands (CNMI), with ash, and providing scientists with important opportunities to study this volcano. The eruption was first reported by the National Oceanic and Atmospheric Administration's Volcanic Ash Advisory Center at 12:32 GMT, based on satellite images of the ash cloud. At about the same time, unusual light flares were observed from an approaching small ship, the Super Emerald, which was carrying a group of seismologists from Washington University in St. Louis, Scripps Institution of Oceanography, and the CNMI Emergency Management Office. As morning broke, the ship was approximately 10 km from the island, and those on board witnessed billowing ash and gas rise from the volcano's caldera to form a great cloud exceeding 6 km in altitude (Figure 1).The scientists were in the region installing land seismographs for the Mariana Subduction Factory Imaging Experiment, a joint U.S. Japanese deployment of 20 land broadband seismographs and 58 ocean bottom seismographs funded (on the U.S. side) by the Margins program of the National Science Foundation. The experiment has the goal of imaging the magma production regions and mantle flow patterns within the upper mantle beneath the Mariana arc and backarc (see http://epsc.wustl.edu/seismology/MARIANA).