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Anatahan’s ash plumes affecting visibility
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Posted on May 30 2005
Ash plumes from Anatahan’s erupting volcano continue to affect navigational visibility, with ash emissions still going on despite fluctuating seismicity on the island.
In a joint report, the U.S. Geological Survey and the Emergency Management Office said yesterday that visibilities of less than 3 nautical miles below the plume have been reported. On Sunday, they said at least two ships beneath the plume in the Philippine Sea reported visibilities of just 1.2 and 2.5 nautical miles.
Citing satellite images taken by the Air Force Weather Agency, the USGS and the EMO said yesterday that a plume of ash and steam was rising to an altitude of 14,000 feet from the volcano. The agencies said the plume, although less denser than Sunday’s, extended about 450 nautical miles northwest of Anatahan.
The agencies also said that a thin plume of ash and volcanic smog extended about 1,300 nautical miles from west-southwest to northwest of the volcano’s summit, affecting visibility. But they said that seismicity on Anatahan has been declining since yesterday morning after escalating in the past days.
The EMO maintained that conditions could change rapidly, warning aircraft to pass upwind of Anatahan or beyond 10 nautical miles downwind from the island. It reminded aircraft to exercise due caution within 10 nautical miles of Anatahan.
Last April 6, the volcano suddenly unleashed its fury and recorded its strongest historical eruption, spewing ash some 50,000 feet into the air. The USGS said the volcano expelled about 50 million cubic meters of ash in that eruption.
