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Anatahan volcano belches ash anew
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Posted on Mar 28 2005
Anatahan’s rumbling volcano spewed ash that reached an altitude of about 19,000 feet over the weekend, the Emergency Management Office and the U.S. Geological Survey reported yesterday.
The agencies said the plume was monitored by the Air Force Weather Agency, which detected a “hot spot” on the island.
“Plume height declined soon afterward to below 10,000 feet and extended to about 25 nautical miles to the southwest,” the agencies said.
They said, though, that the volcanic activity continues to fluctuate, saying it dropped significantly by Saturday afternoon.
“During the 24 hours prior to that, harmonic tremor increased over about 14 hours to a new high since mid-February,” they said.
As of yesterday, the agencies said that seismicity level on Anatahan had been very low.
The EMO and the USGS reported last week that lava was flowing from the volcano’s crater. At one point last week, the agencies described the island’s seismicity as “moderately high.”
The volcano has been erupting for the third time this year since March 18, spewing clouds of ash into the air just days after a scientific mission collected volcanic rock samples from Anatahan and measured emissions of sulfur dioxide, a major air pollutant.
Anatahan’s third historical eruption peaked on Jan. 26 and Feb. 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 volcanic smog nearly 600 miles downwind.
Fresh lava covered the entire crater floor by up to about one kilometer in diameter some two weeks later, the agencies said.
Anatahan’s volcano first erupted after centuries of dormancy on May 10, 2003, with ash plume rising to an altitude of over 30,000 feet that covered over 1-million-square kilometers of airspace above the Pacific Ocean. That eruption, which ceased by mid-June that year, deposited about 10-million cubic meters of material over Anatahan Island and the sea. The second batch of volcanic eruptions happened from April to June 2004.
