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ALASKA VOLCANO OBSERVATORY
Friday, February 18, 2005 1:30 AM AST (22:30 UTC)
MOUNT VENIAMINOF VOLCANO (CAVW #1102-07)
56°10'N 159°23'W, Summit Cone Elevation 7,073 ft (2,156 m)
Current Level of Concern Color Code: ORANGE
Mount Veniaminof has not been visible in web camera images all week due to
cloudy conditions. The most recent unobscured satellite view on Saturday,
February 12 showed a thermal anomaly in the vicinity of the intracaldera
cone. Satellite views on February 15 showed a possible thermal anomaly
through clouds. No ash emissions were observed above the cloud cover.
However, it is likely that low-level strombolian eruptive activity
continues at Veniaminof based on seismicity and available satellite data.
The Level of Concern Color Code for Mount Veniaminof Volcano remains
Seismicity has remained above background all week at Veniaminof. In the
past week the character of seismicity has changed slightly, showing
frequent periods of continuous banded volcanic tremor. However amplitudes
of seismic activity have not increased. This activity is consistent with
explosions from the active cone, however there is no indication that these
bursts are rising more than 13,000 feet above sea level.
This type of eruption produces explosions of ash, blocks, and lava with
little or no warning. These explosions could pose a hazard to people and
low-flying aircraft in the vicinity of the active cone. We expect any
ashfall to remain largely within the summit caldera, however light ash
falls outside of the summit caldera are possible.
As of yet, there is no sign that a lava flow has formed, although this
could occur at any time based on previous historical eruptions at
Web-camera pictures of Mount Veniaminof are available on the internet at:
Mount Veniaminof volcano is an andesitic stratovolcano with an ice-filled
10-km diameter summit caldera located on the Alaska Peninsula, 775 km (480
mi) southwest of Anchorage and 35 km (22 mi) north of Perryville.
Veniaminof is one of the largest (~ 300 km3) and most active volcanic
centers in the Aleutian Arc and has erupted at least 12 times in the past
200 years. The most recent significant eruption of the volcano occurred in
1993-95 and was a moderate Strombolian eruption from the main intracaldera
cone in the northwest sector of the caldera above Cone Glacier. The
eruption was characterized by intermittent low-level emissions of steam and
ash, and a small lava flow was extruded into the summit caldera ice field
producing an ice pit. Minor ash-producing explosions occurred in 2002,
2004, and in recent weeks. Previous historical eruptions have produced ash
plumes that reached 6,000 m (20,000 ft) above sea level and ash fallout
that blanketed areas within about 40 km (25 mi) of the volcano.
MOUNT SPURR VOLCANO (CAVW#1103-04)
61°18' N 152°15' W, Summit Elevation 11,070 ft (3,374 m)
Current Level of Concern Color Code: YELLOW
Elevated levels of seismicity continue to be recorded at Mount Spurr. No
activity was observed in satellite and web camera images this week. There
are no indications that an eruption is imminent.
Web-camera pictures of Mount Spurr are available on the internet at:
Mount Spurr volcano is an ice- and snow-covered stratovolcano located on
the west side of Cook Inlet. The only known historical eruptions occurred
in 1953 and 1992 from the Crater Peak flank vent located 3.5 km (2 mi)
south of the summit of Mount Spurr. These eruptions were brief, explosive,
and produced columns of ash that rose up to 20 km (65,000 ft) above sea
level and deposited several mm of ash in south-central Alaska, including
approximately 6 mm of ash on Anchorage in 1953. The last known eruption
from the summit of Mount Spurr was more than 5,000 years ago. Primary
hazards during future eruptions include far-traveled ash clouds, ash fall,
pyroclastic flows, and lahars or mudflows that could inundate drainages all
sides of the volcano, but primarily on the south and east flanks.
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 27 volcanoes in Alaska.
Satellite images of all Alaskan volcanoes are analyzed daily for evidence
of ash plumes and elevated surface temperatures. Some volcanoes may
currently display anomalous behavior but are not considered to be at a
dangerous level of unrest. Wrangell, Redoubt, Iliamna, Augustine, Snowy,
Griggs, Katmai, Novarupta, Trident, Mageik, Martin, Aniakchak, Pavlof,
Dutton, Isanotski, Shishaldin, Fisher, Westdahl, Akutan, Makushin, Okmok,
Great Sitkin, Kanaga, Tanaga, and Gareloi volcanoes are in color code GREEN
. All are at or near normal levels of background seismicity. AVO did not
detect ash plumes or significant elevated surface temperatures in the
vicinity of any volcano.
ABBREVIATED COLOR CODE KEY (contact AVO for complete description):
GREEN volcano is dormant; normal seismicity and fumarolic activity
YELLOW volcano is restless; eruption may occur
ORANGE volcano is in eruption or eruption may occur at any time
RED significant eruption is occurring or explosive eruption
expected at any time
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
Tom Murray, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
John Eichelberger, Coordinating Scientist, UAF-GI
email@example.com; (907) 474-5530
The Alaska Volcano Observatory is a cooperative program of the U.S.
Geological Survey, the University of Alaska Fairbanks Geophysical
Institute, and the Alaska Division of Geological and Geophysical Surveys.