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ALASKA VOLCANO OBSERVATORY
Friday, January 21, 2005 1:00 PM AST (22:00 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
The Level of Concern Color Code for Mount Veniaminof Volcano remains
ORANGE. Over the past week, seismic data, web camera views, and satellite
images all indicate that low-level ash emissions at the volcano continue.
Seismicity this week is similar to what was observed the previous week,
consisting of low-amplitude volcanic tremor with occasional larger bursts.
When weather permitted, satellite imagery showed anomalous heat at the
summit cone, consistent with hot blocks and ash being ejected from the
active vent, and the web camera showed intermittent ash plumes reaching as
high as 10,000 ft (3,000 m) above sea level. Occasional stronger bursts of
seismic tremor over the past 24 hours may indicate plumes to higher levels
but not above 13,000 ft (4,000 m).
Mount Veniaminof has been at ORANGE since January 10, 2005. Very weak
volcanic tremor was first observed on January 1 and it significantly
increased in magnitude over the next week. Beginning on January 8 satellite
images showed a heat anomaly in the vicinity of Veniaminof’s summit. Web
camera views showed that small ash emissions from the intracaldera cone of
Mount Veniaminof, some reaching nearly 13,000 ft (4,000 m) above sea level,
were occurring more or less continuously from January 8-10. The maximum
amplitude of the seismicity so far during this period has slightly exceeded
that observed during the previous phase of unrest, which ended in September
2004. An overflight of the volcano on January 11 showed no evidence of lava
flows or substantial glacial melting.
Low-level strombolian activity that ejects blocks of hot rock and lava
could occur with little or no warning, though the ejecta would stay within
the summit caldera. We expect steam and ash emissions to continue and could
pose a hazard to people and low-flying aircraft in the vicinity of the
active cone. Light ash falls outside of the summit caldera are possible.
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.
Seismicity rates are slightly higher than last week, with an average of 15
located earthquakes per day. No activity was observed in satellite and web
camera images this week.
An overflight of Mount Spurr on Wednesday, January 12 showed that the
summit melt hole remains and that substantial areas of bare rock are still
present. These observations indicate continuing higher-than-normal heat
flow from the volcano.
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, Acting 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.