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Archived Report
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ALASKA VOLCANO OBSERVATORY

WEEKLY UPDATE

Friday, February 11, 2005 11:30 AM AST (20:30 UTC)



MOUNT VENIAMINOF VOLCANO (CAVW #1102-07)

5610'N 15923'W, Summit Cone Elevation 7,073 ft (2,156 m)

Current Level of Concern Color Code: ORANGE



Low-level strombolian eruptive activity continues at Veniaminof. During

periods of clear viewing conditions on February 9, ash bursts rising a few

thousand feet above the intracaldera cone were visible in web camera

images. AVO received no further reports of visible incandescence, however

cloudy conditions have prevailed much of the week. Satellite images

continue to show a thermal anomaly in the vicinity of the intracaldera

cone, consistent with the presence of hot material at the vent. The Level

of Concern Color Code for Mount Veniaminof Volcano remains ORANGE.



Seismicity has remained above background all week at Veniaminof. On

Thursday morning, a distinct increase in the amplitude and frequency of

events began and this trend continues today. This activity is consistent

with more energetic 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

Veniaminof.



Web-camera pictures of Mount Veniaminof are available on the internet at:



http://www.avo.alaska.edu/avo4/atlas/volc/venia/veni2004/index.htm



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)

6118' N 15215' 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:



http://www.avo.alaska.edu/avo4/atlas/volc/spurr/spurr2004/index.html



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

occurring

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



CONTACT INFORMATION:



Tom Murray, Scientist-in-Charge, USGS

tlmurray@usgs.gov (907) 786-7497



John Eichelberger, Coordinating Scientist, UAF-GI

eich@gi.alaska.edu; (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.

Volcano Alert Levels
NORMAL
Volcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.
ADVISORY
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
WATCH
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway but poses limited hazards.
WARNING
Hazardous eruption is imminent, underway, or suspected.
Aviation Color Codes
GREEN
Volcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.
YELLOW
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
ORANGE
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway with no or minor volcanic-ash emissions [ash-plume height specified, if possible].
RED
Eruption is imminent with significant emission of volcanic ash into the atmosphere likely OR eruption is underway or suspected with significant emission of volcanic ash into the atmosphere [ash-plume height specified, if possible].
PDF version of these definitions
URL: avo.alaska.edu/activity/avoreport_archives.php
Page modified: June 11, 2012 11:50
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