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ARCHIVED REPORT
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ALASKA VOLCANO OBSERVATORY

WEEKLY UPDATE

Friday, February 24, 2006 2:30 PM AKST (2330 UTC)




AUGUSTINE VOLCANO (CAVW#1103-01-)

59°21'48"N 153°26'W , Summit Elevation 4134 ft (1260 m)

Current Level of Concern Color Code: ORANGE



Unrest continues at Augustine Volcano. Over the past week, seismicity has been relatively low but remains above background levels. Seismic data indicate that small rockfalls and avalanches from the lava dome are occurring intermittently. Satellite, high-resolution near-infrared, and low light camera images show that a thermal anomaly in the summit area persists. These data indicate that the lava dome at the volcano's summit continues to grow slowly.



During a visit to the island on February 20, staff geologists examined and sampled several flowage deposits emplaced during the 2006 eruption, made observations of the summit dome, and measured temperatures of the summit area and flanks of the volcano. AVO staff are on the island today to perform maintenance on geophysical instruments. An overflight to measure gases and make observations is also in progress today.



Observations this week show that a plume composed of variable amounts of gas, steam, and small amounts of ash is being emitted intermittently from Augustine's summit. Occasional, but localized ash clouds and light ash fall will be produced by collapses of the lava dome. Evidence of light ash fall on the flanks of the volcano is visible in images from the on-island web camera this week.



Dome building eruptive activity will likely continue over the next few days or weeks and may continue intermittently over the next several months. During dome building eruptions, brief, energetic explosions can occur with little or no warning. Such explosions could produce larger amounts of ash leading to the formation of drifting ash clouds that could rise more than 25,000 feet above sea level.



AVO is monitoring the situation closely and the observatory remains staffed 24/7. For up-to-date Ashfall Advisories and wind trajectories, please refer to the National Weather Service website: http://pafc.arh.noaa.gov/augustine.php



Augustine Volcano is a 1260 m high (4134 ft) conical-shaped island stratovolcano located in southern Cook Inlet, about 290 km (180 mi) southwest of Anchorage, Alaska and 120 km (75 mi) southwest of Homer, Alaska. Historically, Augustine is the most active volcano in the Cook Inlet region with significant eruptions in 1812, 1883, 1908, 1935, 1963-64, 1976, and 1986. These eruptions were primarily explosive events that produced volcanic ash clouds (to 30,000-40,000 feet above sea level), ash fall, pyroclasic flows, and lava domes or flows. During the 1883 eruption, a large avalanche on the north flank of the volcano flowed into Cook Inlet and may have initiated a tsunami observed at Nanwalek, about 90 km to the east.



KOROVIN VOLCANO (ATKA ISLAND) (CAVW#1101-16)

52°22'52"N 174°9'15"W , Summit Elevation 5030 ft (1533 m)

Current Level of Concern Color Code: YELLOW



The level of concern color code for Korovin Volcano was elevated from Green to YELLOW on Wednesday (2/22/06) of this week in response to elevated seismicity. Distinct seismic signals were recorded four of six days between January 17 and 22, with a sustained, 11 minute-long seismic signal on February 22, indicating unrest at this volcano.



Since February 22, seismicity has decreased and no distinct seismic signals like those recorded earlier have been detected. Clouds have obscured views of the volcano by satellite since February 22. A pilot report on February 22 indicated that the summit area was obscured by clouds but the flanks showed no signs of ash fall and there was no steam plume above the volcano. A brief view of the summit area by observers in the village of Atka saw no obvious signs of activity on February 23. AVO has received no reports of activity at the volcano. There are no indications that an eruption is imminent.



AVO is monitoring the situation closely and will provide information should activity increase.



Korovin Volcano is a 1553 m high stratovolcano located on the northern part of Atka Island in the central Aleutian Islands, about 184 km (110 mi) east of Adak, 538 km (350 mi) west of Dutch Harbor, and 1760 km (1100 mi) southwest of Anchorage. The volcano has two distinct summit vents about 0.6 km apart, that have been the sites of eruptive activity as recently as June, 1998. Korovin has erupted several times in the past 200 years, including 1907, 1951, 1953, 1954, 1973, 1976, 1986, 1987, 1996, 1998, and 2005. All of these eruptions produced minor amounts of ash and occasional but small lava flows. Reports of the height of the ash plume produced by the 1998 eruption ranged from 4900 to 9200 m (16,000 to 30,000 feet) above sea level.



OTHER ALASKA VOLCANOES

Seismic activity is monitored in real time at 30 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, Spurr, Redoubt, Iliamna, Snowy, Griggs, Katmai, Novarupta, Trident, Mageik, Martin, Peulik, Ukinrek Maars, Aniakchak, Veniaminof, 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:

Chris Waythomas, Acting Scientist-in-Charge, USGS

chris@usgs.gov (907) 786-7497



Steve McNutt, Acting Coordinating Scientist, UAF-GI

steve@giseis.alaska.edu (907) 474-7131



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].

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Page modified: May 27, 2014 10:23
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