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COOK INLET VOLCANOES
Increased earthquake activity at Iliamna Volcano, which began several weeks ago, continued during the past week. The magnitudes of these earthquakes mostly range from 0.1 to 1.0, too small to be felt. The largest earthquake of the swarm occurred on August 19, and had a magnitude of 3.2. A similar but less intense cluster of earthquakes occurred at Iliamna during mid-May of this year. Fluctuations in the rate of small earthquakes are common at volcanoes, and the present earthquake activity at Iliamna, while persistent, does not necessarily portend eruptive activity. AVO plans to install two additional seismic stations on the volcano this week to more closely monitor the activity.
Iliamna is a deeply dissected stratovolcano located 225 km southwest of Anchorage in the Aleutian Range. The volcano is mostly covered with perennial snowfields and valley glaciers. No historic eruptive activity has been documented at Iliamna, however, a prominent fumarole field located near the summit frequently produces small steam plumes commonly visible from Anchorage and the Kenai Peninsula on clear days.
Seismic activity at Spurr, Redoubt, and Augustine volcanoes remains at normal background levels.
AVO maintains a computerized alarm system capable of
notifying AVO seismologists during non-business hours should unusual seismic activity occur at Spurr, Redoubt, Augustine, or Akutan volcanoes.
AVO continues to test new seismic networks at Pavlof, Dutton, Makushin, Akutan, and Katmai area volcanoes. Reports on these volcanoes will be added to the AVO weekly update as data acquisition and analysis become reliable. We anticipate that this will occur by mid-November.