2025 Mw 7.0 Hubbard Glacier Earthquake: Seismic Hazard in Fault Corridor
Description:
On 6 December 2025, the Mw 7.0 Hubbard glacier earthquake occurred ~80 km north of Yakutat, Alaska, within a tectonically complex setting. The earthquake was widely felt across Alaska and the Yukon Territory, producing ~700 landslides yet resulting in no reported injuries or structural damage, largely due to its remote location. Preliminary rupture estimates align with the NW-SE trending strands of the Fairweather fault in southeast Alaska based on aftershock distribution and a finite fault model from the United States Geological Survey (USGS). Historically, the Fairweather fault system has produced several destructive earthquakes and triggered landslides, including the 1958 Mw 7.9 Lituya Bay event on its southern segment. The Hubbard glacier earthquake occurred on the northern segment of the Fairweather fault, where fault geometry is complex with hypothesized fault strands connecting it to the Central Denali fault through a connector fault. Therefore, despite the alignment with the regional fault trend, it is presently unclear whether the earthquake occurred on a mapped or an unmapped fault with associated known/unknown seismic hazard.
In this study, we synthesize observations of the earthquake in the context of possible activation along unmapped faults. The vigorous aftershock sequence–2000 aftershocks in the first month >M2–allows us to map the extent and orientation of activated fault strands. We examine the published aftershock distributions as well as versions using several absolute and relative relocation methods. Subsequently, we estimate best-fitting focal mechanisms with associated uncertainties for the mainshock and selected aftershocks using regional waveform moment tensor inversions (MTUQ, Thurin et al., 2025). Finally, we develop Coulomb stress change models for the region using (i) the published USGS finite fault model, and (ii) a new two-fault model based on our relocations and moment tensor analysis. These stress changes are also computed for mapped neighboring faults to assess regional seismic hazard.
Session: Linking Subduction Zone Processes and Cascading Hazards in Alaska, Cascadia, Chile and Beyond - III
Type: Oral
Date: 4/16/2026
Presentation Time: 04:30 PM (local time)
Presenting Author: Revathy M. Parameswaran
Student Presenter: No
Invited Presentation:
Poster Number:
Authors
Revathy Parameswaran Presenting Author Corresponding Author rmparameswaran@alaska.edu University of Alaska Fairbanks |
Ezgi Karasozen ekarasozen@alaska.edu University of Alaska Fairbanks |
Julien Thurin jthurin@alaska.edu University of Alaska Fairbanks |
Michael West mewest@alaska.edu University of Alaska Fairbanks |
Ronni Grapenthin rgrapenthin@alaska.edu University of Alaska Fairbanks |
Austin Holland aaholland3@alaska.edu University of Alaska Fairbanks |
Carl Tape ctape@alaska.edu University of Alaska Fairbanks |
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2025 Mw 7.0 Hubbard Glacier Earthquake: Seismic Hazard in Fault Corridor
Category
Linking Subduction Zone Processes and Cascading Hazards in Alaska, Cascadia, Chile and Beyond