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Anatahan’s volcano reawakens, emits steam and ash
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Posted on Nov 11 2004
Anatahan’s volcano continues to emit steam and ash up to 200 feet above the crater after reawakening from a very low seismic activity beginning September.
Sometime in July, the Emergency Management Office and the U.S. Geological Survey reported that the volcanic eruption already ended after strombolian explosions stopped. The agencies also said that seismic activity on the island dropped to dramatically low levels.
Yesterday, the agencies said that very small but long-period seismic events that have been occurring since September continue.
A recent overflight by the EMO also confirmed that the volcano has been emitting steam and ash up to 200 feet. Sulfur dioxide could be detected within a mile south of the crater.
“The occurrence rate [of seismic activities] increased on Oct. 12 to a rate of one event every 6-14 seconds, beginning several hours after the onset of a series of intense tropical storms and depressions,” the agencies said. “The seismicity rate remained high for several weeks as a series of intense tropical depressions and storms continued to strike the island.”
The EMO and the USGS also noted two recent earthquakes that were recorded on the island, including a 5.1-intensity tremor that occurred about 6:01am Tuesday and a 4.4-strong quake about 5:58pm Saturday.
Both earthquakes were located about 250 kilometers south-southeast of Anatahan along the Marianas subduction zone, the agencies said.
The current volcanic and seismic activities on Anatahan resumed in September after the agencies observed that the eruption ended in July. The previous batch of activities, meanwhile, began in late March this year, after remaining at low levels months after the big eruption in May 2003.
Anatahan remains off-limits to the public, except for government and its approved scientific missions.
“Although the volcano is not currently dangerous to most aircraft within the CNMI airspace, conditions may change rapidly, and aircraft should pass upwind of Anatahan or farther than 30 km downwind from the island and exercise due caution within 30-50 km of Anatahan,” the EMO said.
