AVO Weekly Update:
Friday, July 20, 2007 3:00 PM AKDT (2300 UTC)
CLEVELAND VOLCANO (CAVW#1101-24-)
52°49′20″ N169°56′42″ W, Summit Elevation 5676 ft (1730 m)
Current Aviation Color Code: ORANGE
Current Volcano Alert Level: WatchWeak thermal anomalies have been observed at Cleveland volcano in satellite images during periods of clear weather over the past month, and were thought to represent occasional low-level eruptive activity. A much more intense thermal anomaly and an associated steam and gas plume were observed on July 20, 2007 in a satellite image from 1525 UTC (0725 ADT). Although unconfirmed by visual reports, this increase in thermal activity is believed to indicate an increase in the intensity of eruptive activity. No ash emissions have been detected in satellite data since October 2006, but the possibility of an explosion sending an ash cloud to heights in excess of 20,000 ft above sea level has likely increased.
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 with ash plumes that could exceed 20,000 ft above sea level can occur without warning and may go undetected on satellite imagery.
KOROVIN VOLCANO (ATKA ISLAND) (CAVW#1101-16)
52°22′48″ N174°9′22″ W, Summit Elevation 5030 ft (1533 m)
Current Aviation Color Code: YELLOW
Current Volcano Alert Level: AdvisoryIntermittent, low-level seismic activity continues at Korovin. Clouds obscured the volcano in satellite views most of the week. AVO has received no new information about activity at Korovin this past week.
Korovin has erupted several times in the past 200 years, most recently in 1998. Eruptions typically produce minor amounts of ash and occasional, small lava flows. Ash plume heights could exceed 20,000 ft above sea level. Korovin occasionally produces large steam plumes from its summit.
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, Ugashik-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.
