ALASKA VOLCANO OBSERVATORY STATUS REPORT
U.S. Geological Survey
Thursday, August 7, 2008, 2:26 PM AKDT (Thursday, August 7, 2008, 22:26 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

Earthquake activity in the vicinity of Kasatochi Volcano continues. Earthquakes as large as magnitude 5.6 have been detected by seismic networks in the region and numerous slightly smaller earthquakes have been occurring regularly over the past 12 hours. This morning, a US Fish and Wildlife Service field crew on Kasatochi Island reported periods of continuous ground shaking lasting 5-10 minutes, numerous rockfalls, and strong sulfur smell. Although not confirmed at this time, it is possible that the earthquakes and other signs of unrest indicate magma movement toward the surface. It is not known if the activity will culminate in an eruption of Kasatochi Volcano.




Kasatochi Island represents the emergent summit of a predominantly submarine volcano composed of basaltic and andesitic flows and pyroclastics. Kasatochi has had no known historical eruptions; however, the volcano is mantled by a cover of young appearing pyroclastic debris indicative of relatively recent explosive activity. The island consists of a single, undissected cone with a central lake-filled crater about 0.75 km in diameter. A maximum height of 314 m is on the southern crater rim; elevation of the lake is less than about 60 m. Kasatochi Island is at the northern end of a 15-km-long, 6-km-wide submarine ridge that is normal to the trend of the Andreanof Islands. Water depths along the ridge are less than 90 m; if Kasatochi is constructed entirely on the ridge, the total height of the volcanic pile is only a little more than 400 m.

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

The eruption of Okmok Volcano continues. Seismic activity over the past 24 hours remains elevated and continuous volcanic tremor is still occurring. Ash plumes have not been detected in satellite data over that past 24 hours, but it is likely that the volcano continues to generate low-level ash clouds and ash fall over parts of Umnak Island.


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

Volcanic unrest at Cleveland Volcano has declined. A weak thermal anomaly at the summit was observed in satellite data about 12 hours ago. No ash plumes or have been observed in satellite images since July 29.



Please see http://www.avo.alaska.edu/activity/Cleveland.php for more information.



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 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:

Chris Waythomas, Acting Scientist-in-Charge, USGS
chris@usgs.gov, (907)786-7497

Jon Dehn, Acting Coordinating Scientist, UAFGI
dehn@gi.alaska.edu (907) 474-6499



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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