Origins of the Purcell Mountains Swarm
Description:
Seismicity in Alaska’s Purcell Mountains remains largely absent from published literature, yet the region exhibits vigorous, swarmlike activity. The most recent swarm onset began in February of 2019, producing over 9,600 cataloged events to date. Five events are magnitude 5 or greater and were reportedly felt throughout the region. Broadscale tectonic studies propose this northwestern region of Alaska is predominantly strike-slip faulting with normal faulting constrained farther west. However, available focal mechanisms for this sequence report both strike-slip and normal faulting with temporal variation. This suggests the Purcell Mountains region is structurally more complex than currently represented. We leverage the region’s exceptional data quality and pursue a detailed moment tensor-derived focal mechanism study paired with event relocations. Using the Alaska Earthquake Center’s published hypocenters from the 2019 swarm onset, we first invert moment tensor solutions for the largest events and compare with published solutions as a control. We then invert moment tensor solutions for events without published solutions and with decreasing magnitudes. We aim to characterize the seismic origins of the Purcell Mountains swarm and identify fault structures in this remote region of Alaska.
Session: Compiling Active Faults for Improved Hazard Modeling from Cascadia to Alaska [Poster]
Type: Poster
Date: 4/17/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Sarah
Student Presenter: Yes
Invited Presentation:
Poster Number: 77
Authors
Sarah Noel Presenting Author Corresponding Author sknoel@alaska.edu University of Alaska Fairbanks |
Michael West mewest@alaska.edu University of Alaska Fairbanks |
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Origins of the Purcell Mountains Swarm
Category
Compiling Active Faults for Improved Hazard Modeling from Cascadia to Alaska