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ALASKA VOLCANO OBSERVATORY
Friday September 20, 2002 10:00 AM ADT (1800 UTC)
MT. VENIAMINOF VOLCANO (CAVW #1102-07)
Summit Cone Elevation 7,073 ft (2,156 m)
Current Level of Concern Color Code: YELLOW
On September 10, AVO detected pulses of low-frequency tremor occurring on several seismic stations at Mt. Veniaminof volcano. Over the past week, the overall level of seismic activity has decreased but still remains above background levels. Although this type of seismicity is indicative of volcanic unrest, it does not mean that an eruption is imminent. AVO has not received any visual reports of anomalous activity at Veniaminof and poor weather conditions have limited satellite observations. The Level of Concern Color Code will remain YELLOW because of the anomalous seismicity. AVO will continue to monitor the situation closely, and will issue further updates as information becomes available.
Mt. Veniaminof volcano is an andesitic stratovolcano with an ice-filled 10-km diameter summit caldera located on the Alaska Peninsula, 775 km (480 mi) southwest of Anchorage and 35 km (22 mi) north of Perryville. Veniaminof is one of the largest (~ 300 km3) and most active volcanic centers in the Aleutian Arc and has erupted at least 12 times in the past 200 years. The most recent eruption of the volcano occurred in 1993-95 and was a moderate Strombolian eruption from the main intracaldera cone in the northwest sector of the caldera above Cone Glacier. The eruption was characterized by intermittent low-level emissions of steam and ash, and a small lava flow was extruded into the summit caldera ice field producing an ice pit. Previous historical eruptions have produced ash plumes that reached 6,000 m (20,000 ft) above sea level and ash fallout that blanketed areas within about 40 km (25 mi) of the volcano.
Seismic activity is monitored in real time at 24 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, Snowy, Griggs, Katmai, Novarupta, Trident, Mageik, Martin, Aniakchak, Pavlof, Dutton, Isanotski, Shishaldin, Fisher, Westdahl, Akutan, Makushin, Great Sitkin, and Kanaga 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.