Potential Tectonic Tremor Detected on a Single Ocean Bottom Seismometer Offshore Cascadia
Description:
Observations of tectonic tremor, an emergent seismic signal associated with slow slip, provide important constraints on the plate locking state and associated seismic hazards at subduction zones and other plate boundaries. However, detecting tectonic tremor offshore with ocean bottom seismometers (OBSs) is often complicated by large station spacing and marine-specific emergent noise signals, including T-phases and ship noise. To address these challenges, we develop a single-station tremor detection method that employs a two-stage triggering and classification approach to minimize misdetections caused by marine-specific noise. We validate our method using OBSs in the Hikurangi subduction zone, demonstrating that we can effectively identify network-confirmed offshore tectonic tremor with just one OBS. We then apply this approach to two cabled, buried OBSs located near the deformation front of the Cascadia subduction zone at ~44.5°N. Our results show that shallow OBS burial effectively eliminates bottom current-generated noise, which disrupts tectonic tremor detection. Over 2015-2024, we find evidence for tectonic tremor signals at just one station, 5 km seaward of the deformation front. These signals cannot be easily attributed to instrumental or environmental noise and they are not measured on the other station, 20 km landward. We therefore suggest they are associated with either localized slow slip very near the deformation front or deformation in the outermost wedge. Additional observations are needed to confirm the signal source, but our findings may be the first observation of shallow tremor in Cascadia. Our single-station approach could be adapted elsewhere to search for tectonic tremor where OBS coverage is limited, helping to illuminate fault slip modes in hard-to-reach offshore regions.
Session: ESC-SSA Joint Session:Seismology in the Global Oceans: Advances in Methods and Observations [Poster]
Type: Poster
Date: 4/15/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Zoe
Student Presenter: No
Invited Presentation:
Poster Number: 3
Authors
Zoe Krauss Presenting Author Corresponding Author zkrauss@uw.edu University of Washington |
William Wilcock wilcock@uw.edu University of Washington |
Ken Creager kcc@uw.edu University of Washington |
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Potential Tectonic Tremor Detected on a Single Ocean Bottom Seismometer Offshore Cascadia
Category
ESC-SSA Joint Session:Seismology in the Global Oceans: Advances in Methods and Observations