Printer friendly versionALASKA VOLCANO OBSERVATORY
Friday, August 3, 2007 2:10 PM AKDT (2210 UTC)
52°49'20" N169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Aviation Color Code: ORANGE
Current Volcano Alert Level: Watch
Intermittently visible thermal anomalies at Cleveland indicate that low-level eruptive activity continues. Photographs from July 27 and a pilot report from August 2 document fresh volcanic ejecta mantling the slopes and summit of the volcano. The east portion of Chuginadak Island was also dusted with ash.
No significant ash plumes have been observed during this recent episode of increased activity at Cleveland. However, a sudden explosion sending ash higher than 20,000 ft above sea level could still occur.
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 and ash plumes 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 last significant eruption in the spring of 2001 consisted of 3 explosive events with 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.
KOROVIN VOLCANO (ATKA ISLAND)
52°22'48" N174°9'22" W, Summit Elevation 5030 ft (1533 m)
Current Aviation Color Code: YELLOW
Current Volcano Alert Level: Advisory
Intermittent, low-level seismic activity continues at Korovin throughout the week. On Monday, residents in Atka reported a robust steam plume rising 700-800 ft (200-250 m) above the volcano. These have been noted before and do not indicate a signficant change at the volcano. Clouds obscured the volcano for much of the week preventing clear satellite views.
Korovin Volcano is a 1553-m-high (5030 ft) 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 (2000 ft) apart, that have been the sites of eruptive activity as recently as June, 1998. The most recently active of the vents maintains a small, roiling, lake that occasionally produces energetic steam emissions. Thermal springs and fumaroles located on and near the volcano indicate an active hydrothermal system. Korovin has erupted several times in the past 200 years, including 1907, 1951, 1953, 1954, 1973, 1976, 1986, 1987, 1996, and 1998. 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 31 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, Augustine, Fourpeaked, 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 at Aviation 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
Tom Murray, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Steve McNutt, Coordinating Scientist, UAF
email@example.com (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.