NSF-MARGINS Expedition
to Anatahan Volcano - March 2005

According to the Emergency Management Office (EMO) report distributed in February 2005, the third historical eruption of Anatahan began on January 5, after three days of precursory seismicity. On January 6 frequent strombolian explosion signals began and by the next day ash was rising to 10,000 feet and blowing 40 nautical miles downwind. Bombs a meter in diameter were being thrown hundreds of feet in the air. By January 20 explosions were occurring every 3 to 10 seconds and fresh ejecta and small lava flows had filled the innermost crater to nearly the level of the pre-2003 East Crater floor. The eruption peaked during January 26 and February 2, during which time the volcano sent ash as high as 15,000 to 20,000 feet locally and as far as 100 miles downwind, and vog (volcanic smog) nearly 600 miles downwind. Two weeks later the 2003 crater floor had essentially been entirely covered by fresh lava to a diameter of about one kilometer.

Access this entire 10-page report in Word (1 Mb) or PDF (3 Mb) form.