Giant landslide on the flanks of Mount Iliamna volcano in Alaska

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A very large landslide occurred on the flanks of Mount Iliamna, a volcano located in Alaska, on 20th June 2019.

The landslide appears to be in the order of about 6 km in length, and over 2 km wide at the toe, but the trigger of this landslide is not clear.

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Giant landslide on the flank of Iliamna volcano in Alaska on June 20. Picture via AVO

This landlside just reminds me of the largest tsunami ever that created a superwave higher than the Empire State Building in 1958 in Alaska. It was indeed triggered by a strong M8.3 earthquake at the Fairweather Fault, which resulted in a huge landslide that fell into the narrow inlet of Lituya Bay.

AVO detected seismic and pressure sensor signals associated with a debris avalanche on Red Glacier on the flank of Iliamna Volcano around 4:05 p.m ADT on Thursday, June 20, 2019 (00:05 UTC on June 21, 2019).

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The debris of the landslide on the flanks of Iliamna volcano on June 20, 2019. Picture by Loren Prosser via AVO

The seismic signals from the avalanche were observed on volcano monitoring networks on Illiamna and Redoubt volcanoes. Infrasound from this slide was detected with pressure sensors in Dillingham, Fairbanks, and those on the EarthScope Transportable Array.

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Sentinel 2 image showing the Mount Iliamna landslide on June 25. Image via Sentinel Hub Playground.

The avalanche and subsequent seismicity and infrasound are not considered to be indicative of volcanic unrest.

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The landslide is 6km long and 2km wide. Picture by Dennis Anderson via AVO

Avalanche events are somewhat common at this volcano. The most recent prior to last week’s occurred in April 2019.

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A day before the landslide at Iliamna volcano in Alaska. Picture via AVO

The trigger of this landslide is not clear, but this is not the first large-scale landslide in Alaska in recent years JuneauIcy Bay / Tyndall GlacierGlacier Bay / Lamplugh, and Sitka. SO there is really something brewing up there!

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