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Sarigan earthquakes top 705
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Posted on Aug 17 2005
The seismic swarm recorded on Sarigan has continued with at least 705 earthquakes occurring since Tuesday last week.
The Emergency Management Office and the U.S. Geological Survey also reported that seismicity on Anatahan continues to fluctuate after volcanic activity on the island escalated from late Monday night to early Tuesday morning.
EMO geophysical instrument specialist Ramon Chong said that Anatahan’s seismicity level from late Monday to early Tuesday triggered equipment alarms that indicated high eruptive activity.
“An indirect indication of ash being in the air was that the seismic signals from Sarigan and Anatahan were affected. A similar scenario occurred on April 6 when ash affected telemetry signals,” the EMO and the USGS said in a joint report.
The April 6 activity was Anatahan volcano’s strongest historical eruption, with ash emissions reaching 50,000 feet in the air. Estimated volume of ash emitted by the volcano in that eruption reached 50 million cubic meters.
Yesterday, tremor levels on Anatahan ranged from 25 to 50 percent of peak levels. The agencies said an ash plume rose to approximately 18,000 feet and moved easterly.
