Iliamna Volcano Shows Signs of Activity After a Century of Dormancy

The Iliamna volcano in southern Alaska, quiet for more than 100 years, is showing signs of renewed seismic activity. NASA has described the volcano as “ready to rumble,” though scientists caution the shaking could signal a large avalanche rather than an imminent eruption.

Recent Seismic Activity Raises Concerns

Located near Cook Inlet, Iliamna last erupted in 1867 but has a history of producing avalanches powerful enough to register on seismic monitors. On June 15, the Alaska Volcano Observatory reported hours of nearly continuous shaking, following satellite images captured on June 10.

Avalanches Likely the Cause of the Shaking

Experts say the tremors resemble those caused by the slipping of ice and rock, which often lead to avalanches on the glacier-covered volcano. Iliamna’s unstable mix of volcanic heat, glacial ice, and weakened rock frequently causes these massive slides.

A History of Minor Eruptions and Smoke

Though it has not erupted in over a century, Iliamna has occasionally emitted smoke and light ash, with the last confirmed vapor columns seen in 1958. Other minor activity was reported in the early and mid-1900s but never confirmed as full eruptions.

Close Monitoring Despite Remote Location

Iliamna sits in the Chigmit Mountains of Lake Clark National Park and Preserve. While remote, its activity is closely monitored because communities within 200 miles—including Pedro Bay, Port Alsworth, and Anchorage—could be affected by an eruption or significant avalanche.

No Current Eruption Warning

Despite the recent rumblings, the U.S. Geological Survey has kept Iliamna at a “normal” alert level. Volcanologists continue to monitor it alongside 51 other active volcanoes in Alaska, including the nearby Redoubt Volcano, which is known for more frequent eruptions.

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