Anatahan Volcano Update
Anatahan Volcano Update for April 28, 2004
Submitted Wednesday, April 28, 2004 at 1000 local Anatahan time
Anatahan seismic activity increased abruptly at 0052 4/24 UTC (1052 4/24
CNMI) to
a high level unseen since summer 2003. About that time a low-level
eruption began producing steam and ash to ~2,000 ft (600 m). An
overflight at that time reported incandescent cracks in a fresh lava
flow or dome within the inner crater. The presence of a "cow-pie-shaped"
dome within the inner crater has since been verified. The seismicity
level increased slowly and fairly constantly on the 24th and 25th to a
level similar to that of the eruption of mid-June 2003. Since about 2000
4/25 UTC (0600 4/26 CNMI), the seismicity level has remained at
approximately the same high level. An overflight at 0030-0100 4/26 UTC
(1030-1100 4/26 CNMI)
observed regular puffs of yellow-brown steam and ash rising above the
rim at 30-120 sec intervals, very similar to the rate of seismic events
recorded during the same time. Maximum height of the steam and ash plume
has remained about 2,000 ft (600 m) since 4/24, but this could increase
significantly at any time with little or no warning.
The Emergency Management Office, Office of the Governor, CNMI, has
placed Anatahan Island off-limits until further notice and concludes
that, although the volcano is not currently dangerous to most aircraft
within the CNMI airspace, aircraft should pass upwind of Anatahan or >30
km downwind from the island and exercise due caution within 30-50 km of
Anatahan.
The next seismic update will be at approximately 0000 4/29 UTC (1000
4/29
CNMI). 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
|
