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ALASKA VOLCANO OBSERVATORY
Friday, January 14, 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 was upgraded
from YELLOW to ORANGE on Monday, January 10. At that time, web camera views
showed that small ash emissions from the intracaldera cone of Mount
Veniaminof, some reaching nearly 13,000 ft (3692 m) above sea level, had
occurred more or less continuously over the previous 48 hours. Since then,
activity appears to have declined significantly, though web camera views
have often been obscured by clouds.
Beginning on Saturday, January 8, satellite images showed a heat anomaly in
the vicinity of Veniaminof’s summit. The most recent satellite image,
taken today, shows that the heat anomaly persists, though the intensity may
be less than earlier in the week.
Very weak volcanic tremor was observed starting on January 1, 2005. Over
the next week, the magnitude of the volcanic tremor increased significantly
and there have been frequent small volcanic earthquakes. As of this
writing, seismic activity appears to have peaked on Sunday or Monday,
though activity still remains significantly higher than normal with
occasional bursts of volcanic tremor. The maximum amplitude of the
seismicity so far has slightly exceeded that observed during the previous
phase on unrest, which ended in September 2004.
On overflight of the volcano on Tuesday January 11, showed no evidence of
lava flows, large ballistics from the cone, 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 that steam and ash emissions may 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
Real-time 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 explosions producing small ash 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 average 6 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
to be found. These observations indicate continuing higher-than-normal
heat flow from the volcano.
Real-time 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.