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AVO VOLCANO ACTIVITY NOTIFICATION

ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, September 12, 2008, 1:19 PM AKDT (Friday, September 12, 2008, 21:19 UTC)


KASATOCHI VOLCANO (VNUM #311130)
52°10'9" N 175°30'41" W, Summit Elevation 1030 ft (314 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Low level seismicity at Kasatochi continues. Intermittent power outages are affecting AVO's seismic networks in the Kasatochi area. Thus, we have been unable to monitor Kasatochi from the nearby networks much of this week. Satellite views were cloudy throughout the week. Views on Monday suggest a possible weak thermal anomaly.

Kasatochi Volcano does not have a seismic network, thus AVO depends on networks on neighboring islands to monitor earthquake activity there. For this reason, low-level seismicity may not be detected. Renewed volcanic activity is possible at any time with little or no warning.



OKMOK VOLCANO (VNUM #311290)
53°23'49" N 168°9'58" W, Summit Elevation 3520 ft (1073 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Seismicity at Okmok volcano continues at low levels. There has been a small increase in seismic activity over the last 24 hours. Satellite views remain cloudy throughout the week. An AVO field crew working on the volcano since Wednesday reported steaming, but not other eruptive activity. Although the level of seismicity has declined, it is possible for vigorous ash emissions to resume at any time. The AVO field crew repaired one seismic and one GPS station. They have also gathered ash samples, made visual observations, and photographed the volcano. They will be working at Okmok through September 15.


Okmok volcano is a 6-mile-wide caldera that occupies most of the eastern end of Umnak Island, located 75 miles southwest of Dutch Harbor in the eastern Aleutian Islands. Okmok has had several eruptions in historic time typically consisting of ash emissions occasionally to over 30,000 feet ASL but generally much lower; lava flows crossed the caldera floor in 1945, 1958, and 1986. The last eruption occurred in February 1997 and was characterized by lava flows and intermittent ash emissions.

The nearest settlements are Nikolski, population about 35, roughly 45 miles west of the volcano, and a small number of people at the abandoned Fort Glenn military base 10 miles east of the volcano.

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

Clouds obscured Cleveland volcano in satellite and web camera views throughout the week. AVO received no reports of activity at the volcano.

AVO monitors Cleveland Volcano with satellite imagery as weather allows. The lack of a real-time seismic network at Cleveland means that AVO is unable to track local earthquake activity related to volcanic unrest. Short-lived explosions of ash that could exceed 20,000 ft above sea level can occur without warning and may go undetected on satellite imagery.

Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. It is located about 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 had 3 explosive events that produced ash clouds as high as 12 km (39,000 ft) above sea level. This eruption also produced a rubbly lava flow and hot avalanche that reached the sea. The most recent minor ash emissions were observed in October 2006.

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. Augustine, Iliamna, Redoubt, Wrangell, Gareloi, Great Sitkin, Makushin, Fisher, Shishaldin, Isanotski, Pavlof, Veniaminof, Ugashik-Peulik, Griggs, Snowy, Fourpeaked, Aniakchak, Tanaga, Kanaga, Akutan, Westdahl, Dutton, Ukinrek Maars, Martin, Mageik, Trident, Katmai, Novarupta, Spurr, and Korovin 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 volcano.

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:

Peter Cervelli, Acting Scientist-in-Charge, USGS
pcervelli@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF
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.
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