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ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
Friday, February 7, 2014 12:02 PM AKST (Friday, February 7, 2014 21:02 UTC)


SHISHALDIN VOLCANO (VNUM #311360)
54°45'19" N 163°58'16" W, Summit Elevation 9373 ft (2857 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Elevated unrest continues at Shishaldin. A possible volcanic cloud was observed this morning in satellite images beginning around 1545 UTC (6:45 AKST). This cloud may have resulted from a small explosive event at the volcano. The event was small enough that it was not detected by the one working seismic station near the volcano, but it appears to coincide with a signal recorded by a nearby tiltmeter. Satellite images suggest that the cloud may have reached as high as 25,000 ft asl, was ash poor, and short lived. There was no evidence of elevated surface temperatures observed in satellite data following this event, suggesting that it was primarily a gas event and very little to any hot material was produced and deposited on the flanks of the volcano. There have been no visible observations of the volcano since this event and AVO will continue to evaluate new data as it becomes available.

Persistent elevated surface temperatures in the summit crater of Shishaldin have been observed during clear-weather intervals over the past week. Nothing unusual has been seen in seismicity from the nearest working station off the flanks of the volcano.

Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 10 miles (16 km). A small summit crater typically emits a noticeable steam plume with occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including at least 24 confirmed eruptions since 1775. Most of Shishaldin's eruptions have consisted of small ash and steam plumes, although a recent eruption in April-May 1999 produced an ash column that reached a height of 45,000 ft above sea level. Unrest similar to what is currently occurring was last noted during 2009, which did not result in an eruption.

CLEVELAND VOLCANO (VNUM #311240)
52°49'20" N 169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Satellite observations of Cleveland were mostly obscured by clouds over the past week. Weakly elevated surface temperatures at the volcano's summit were last observed on Sunday, February 2. We have received no other reports of activity.

The occurrence of brief, sudden explosions of blocks and ash from the summit vent with little to no warning remains possible. If a large ash-producing event occurs, nearby seismic, infrasound, or volcanic lightning networks should alert AVO staff quickly. However, for some events, a delay of several hours or more is possible. Cleveland volcano does not have a local seismic network and is monitored using only distant seismic and infrasound instruments and satellite data.

Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. It is located about 75 km (45 mi) west of the community of Nikolski, and 1500 km (940 mi) southwest of Anchorage. The volcano's most recent significant eruption began in February, 2001 and it produced 3 explosive events that produced ash clouds as high as 12 km (39,000 ft) above sea level. The 2001 eruption also produced a lava flow and hot avalanche that reached the sea. The last minor ash emission following an explosion was on May 5, 2013.

VENIAMINOF VOLCANO (VNUM #312070)
56°11'52" N 159°23'35" W, Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Seismicity at Veniaminof remains slightly above background. No unusual activity was observed in satellite data, web camera images, or by local observers in the past week.

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 cubic km) and most active volcanic centers in the Aleutian Arc and has erupted at least 13 times in the past 200 years. Recent significant eruptions of the volcano occurred in 1993-95 and 2005. Both were Strombolian eruptions producing lava fountans and minor emissions of ash and gas from the main intracaldera cone. During the 1993-95 activity, a small lava flow was extruded into the ice field producing a melt pit. Minor ash-producing explosions occurred nearly annually between 2002 and 2008. Previous historical eruptions have produced ash plumes that reached 6,000 m (20,000 ft) above sea level (1939 and 1956) and ash fallout that blanketed areas within about 40 km (25 mi) of the volcano (1939).

OTHER ALASKA VOLCANOES

Seismic activity is monitored in real time at 28 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. Akutan, Augustine, Dutton, Fisher, Fourpeaked, Gareloi, Great Sitkin, Griggs, Iliamna, Isanotski, Kanaga, Katmai, Mageik, Makushin, Martin, Novarupta, Okmok, Pavlof, Redoubt, Snowy, Spurr, Tanaga, Trident, Ugashik-Peulik, Ukinrek Maars, and Westdahl volcanoes are in color code GREEN and volcano alert level Normal. 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 of these volcanoes.

Please see http://www.avo.alaska.edu/color_codes.php for complete definitions of Aviation color codes and Volcano alert levels.

VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478

CONTACT INFORMATION:
John Power, Scientist-in-Charge, USGS
jpower@usgs.gov (907) 786-7497

David Fee, Acting Coordinating Scientist, UAFGI
dfee@gi.alaska.edu (907) 322-4085

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].
Contact AVO Privacy Accessibility Information Quality FOIA
URL: www.avo.alaska.edu/activity/avoreport.php
Page modified: May 16, 2014 09:40
Contact Information: AVO Web Team

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