Anatahan Volcano Update
Anatahan Volcano Update for December 23-29
Submitted Tuesday, December 30 at 11:30 a.m. local Anatahan time
For the past week, Anatahan volcanic seismicity has been low, at a level
similar to that of the past several months. There were no apparent eruption
signals or precursory events. Tremor and seismic energy release are at very
low levels.
Recorded seismicity was dominated by reactivation of a tectonic swarm that
began on December 13. These events approached magnitude 4 and were closest
to the Sarigan station, at a slant distance of about 35 km. Seismicity was
particularly pronounced from December 14 at 23:00 UTC to December 15 at
05:00 UTC and December 25 at 13:00 UTC to December 26 at 02:00 UTC. Roughly
35 of these earthquakes were large enough to be recorded on both the Sarigan
and the Anatahan crater seismic stations over the past week.
Two large regional events were recorded by the seismic network this week.
The first was a magnitude 4.8 on December 23 at 07:41 UTC. This event was
located by the National Earthquake Information Center about 40 km (25 miles)
west-northwest of Agrihan, at a depth of 205 km. A second earthquake,
apparently from south of Saipan, occurred on December 29 at 14:54 UTC. This
event is approximately 210 km (130 miles) south of Anatahan. Two large
distant earthquakes were also recorded in the Loyalty Islands on December 26
at 21:26 UTC (M6.5) and December 27 at 16:01 UTC (M7.0).
Contact persons:
Juan Takai Camacho, Geophysical Seismic Technician, EMO Saipan; tel:
(670) 322-9528, fax: (670) 322-7743, email: juantcamacho@hotmail.com
Ramon Chong, Geophysical Instrument Specialist, EMO Saipan; tel: (670)
322-9528, fax: (670) 322-7743, email: rcchongemo@hotmail.com
Frank Trusdell, Geologist, USGS; tel: (808) 967-8812, fax: (808) 967-8890,
email: trusdell@usgs.gov
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