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Anatahan activity on the rise again
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Posted on May 29 2005
Volcanic activity on Anatahan appeared to be escalating, as volcanic ash emissions continued at an increasing rate, which already affected navigational visibility as far west as the Philippines.
Yesterday’s satellite images of the ash plume showed that it has become denser than Saturday’s plume, based on monitoring activities by the Air Force Weather Agency. Yesterday’s plume rose to altitudes of 15,000- to 18,000 feet, which extended about 400 nautical miles of Anatahan.
But a thin plume of ash and volcanic smog also extended about 1,100 nautical miles from west-southwest to northwest of the volcano’s summit, affecting navigational visibility at the Philippine Sea.
In a joint report, the U.S. Geological Survey and the Emergency Management Office said at least two ships beneath the plume in the Philippine Sea reported visibilities of just 1.2 and 2.5 nautical miles.
Volcanic ash emissions also pose a threat to aviation safety. Recently, local and federal agencies that include the EMO and the USGS convened to lay the groundwork for a volcanic ash response plan for the CNMI.
Volcanic ash threatens jets and aircraft in the air, as it forms deposit in engines, restricts airflow, and clogs fuel nozzles. Minute particles of volcanic ash also contaminate aircraft’s ventilation, lubrication, hydraulic and electronic systems. They cause erosion and pitting of leading edges of windshields and landing lights, as well as erosion of compressor blades.
Meanwhile, the USGS and the EMO reported that seismicity on Anatahan has been increasing. But they added yesterday that the rate of increase has slowed considerably in the past 72 hours.
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 that spewed out some 50,000 feet into the air. The USGS said the volcano expelled about 50 million cubic meters of ash in that eruption.
