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Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with base diameter of approximately 10 miles (16 km). A small summit crater typically emits a noticable steam plume with occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, erupting at least 27 times since 1775. The most recent eruptive period occurred in late 1995 and early 1996 and consisted of minor explosions that produced low level steam and ash emissions.
During the past week, National Weather Service personnel in Cold Bay, 58 miles (93 km) east-northeast of the volcano, observed anomalous steaming at Shishaldin volcano. On Tuesday, a vigorous steam plume rose as high as 6000 feet (1830 m) above the vent and a long plume drifted downwind. Satellite imagery on that same day showed the steam plume and a thermal anomaly at the vent. The steam activity decreased throughout the week to light puffs rising a few hundred feet above the vent, however the thermal anomaly at the vent persists. A new seismic net monitoring Shishaldin volcano recorded slightly elevated seismicity beginning the end of January, but the seismicity currently has not reached a level to indicate that a major eruption is expected. As long as the thermal anomaly persists, a low-level ash burst could occur with little or no warning.
OTHER ALASKA VOLCANOES
Spurr, Redoubt, Iliamna, Augustine, Snowy, Griggs, Katmai,
Novarupta, Trident, Mageik, Martin, Aniakckak, Pavlof,
Dutton, Akutan, Isanotski, Fisher, Westdahl, and
Makushin volcanoes are all at or near normal levels of