Low Frequency Earthquakes in the Alaska Subduction Zone
Description:
The Alaska, Cascadia, and Southern Chile subduction zones share several key features including Low-Frequency Earthquakes (LFEs) which occur along the subduction interface and provide important information on local slip. We analyzed publicly available seismic records from Alaska between 2013 and 2018 to identify repeating seismic signatures during tremor-active periods, allowing us to construct LFE templates (stacks of multiple events from the same region which improve the signal-to-noise ratio). In total, we added 45 new templates to the six previously published for the region (Chuang et al., 2017). The new templates are distributed throughout most of the previously defined tremorgenic zone (Wech, 2016) and cover a larger area than previous LFE catalogs for the Alaska subduction zone. Owing to stacking, several P- and S-wave arrivals are clearly observable above the noise level significantly improving hypocentral constraints. Estimated depths range from 35 to 50 km, with location uncertainties of 0.4–2.1 km horizontally and 0.8–3.3 km vertically.
We applied a novel technique that incorporates S-wave polarization directions to better constrain the focal mechanisms of these events. Preliminary results provide new insights into the regional tectonic deformation, particularly in the complex corner where double-verging subduction has been proposed. Our observations indicate that the deformation cannot be explained by a single process. Instead, we identify: (1) thrust events aligned with the NW-dipping Alaska subduction zone; and (2) events that could differ from expected NE thrust along the eastern edge of the tremor-genic zone. Overall, this work advances understanding of slow-slip processes in Alaska and their role in accommodating the complex subduction geometry. These findings may also have important implications for similar geometries along the margins of the Cascadia and Southern Chile subduction zones.
Session: Linking Subduction Zone Processes and Cascading Hazards in Alaska, Cascadia, Chile and Beyond [Poster]
Type: Poster
Date: 4/16/2026
Presentation Time: 08:00 AM (local time)
Presenting Author: Nicolas A. Perez Estay
Student Presenter: Yes
Invited Presentation:
Poster Number: 130
Authors
Nicolas Perez Estay Presenting Author Corresponding Author nicolas.perezestay@ubc.ca University of British Columbia |
Michael Bostock bostock@eoas.ubc.ca University of British Columbia |
Charles Sammis csammis@eoas.ubc.ca University of British Columbia |
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Low Frequency Earthquakes in the Alaska Subduction Zone
Category
Linking Subduction Zone Processes and Cascading Hazards in Alaska, Cascadia, Chile and Beyond