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Deep long-period earthquakes at Akutan Volcano are more directly related to magmatic processes than volcano-tectonic earthquakes
  • Zilin Song,
  • Yen Joe Tan,
  • Diana C. Roman
Zilin Song
Chinese University of Hong Kong
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Yen Joe Tan
The Chinese University of Hong Kong

Corresponding Author:[email protected]

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Diana C. Roman
Carnegie Institution of Washington
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Abstract

Both volcano-tectonic (VTs) and deep long-period earthquakes (DLPs) have been documented at Akutan Volcano, Alaska and may reflect different active processes. In this study, we perform high-resolution earthquake detection, classification, and relocation using seismic data from 2005-2017 to investigate their relationship with underlying magmatic processes. We find that the 2,787 VTs and 787 DLPs are concentrated above and below the shallow magma reservoir respectively. The DLPs’ low-frequency content is likely a source instead of path effect considering its uniformity across stations. Both VT and DLP swarms occur preferentially during inflation episodes with no clear migration. However, the largest VT swarms occur during non-inflating periods, and only VT swarms contain repeating events. Therefore, we conclude that the VTs represent fault rupture triggered by magma/fluid movement or larger earthquakes, while the DLPs are directly related to unsteady magma movement through a complex pathway or represent slow fault ruptures triggered by magma movement.