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Return from Dormancy: Rapid inflation and seismic unrest at Mt. Edgecumbe (L’ux Shaa) Volcano, Alaska
  • +3
  • Ronni Grapenthin,
  • Yitian Cheng,
  • Mario Angarita,
  • Darren Tan,
  • Franz Josef Meyer,
  • David Fee
Ronni Grapenthin
University of Alaska Fairbanks

Corresponding Author:[email protected]

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Yitian Cheng
University of Alaska Fairbanks
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Mario Angarita
University of Alaska
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Darren Tan
University of Alaska Fairbanks
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Franz Josef Meyer
University of Alaska Fairbanks
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David Fee
University of Alaska Fairbanks, Geophysical Institute
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Abstract

In April 2022 a seismic swarm near Mt. Edgecumbe in southeast Alaska suggests renewed activity at this dormant volcano located in a transform fault setting. Oral Tlingit history describes low-level basaltic eruptions $\approx$800 years ago. Thin rhyolitic tephras deposited 5-4 ka. We analyze synthetic aperture radar data from 2014-2022 and resolve rapid inflation up to 8.7\,cm/yr beginning in August 2018. Bayesian modeling suggests a gently westward dipping sill opened 0.65\,m between 7.6\,km to 5.3\,km depth, centered about 2-3\,km east of Mt. Edgecumbe. Reanalyzed seismicity, recorded 25\,km away, shows increased activity since July 2019. We hypothesize mafic magma ascent through ductile material, accumulating below a silicic seal or in a silicic reservoir, and triggering seismicity in the overburden. Cloud-native open data and workflows enabled discovery and analysis of this rapid inflation within days after going unnoticed for $>$3 years.