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Exploring the Use of Existing Offshore Cabled Infrastructure for Earthquake Early Warning in the Pacific Northwest

A Cascadia subduction zone M8-9 megathrust earthquake will generate extensive offshore fault rupture that will widely impact the Pacific Northwest of North America. However, the existing ShakeAlert earthquake early warning system uses no seafloor sensors, hindering rapid and accurate warnings for such an event. We explore the incorporation of existing offshore cabled infrastructure into the ShakeAlert system. There are two scientific submarine cable networks in Cascadia: the Ocean Observatories Initiative (OOI) Regional Cabled Network offshore Oregon, which currently supports two existing ocean bottom seismometers (OBSs), with four additional OBS deployments planned in the near future, and the Ocean Networks Canada NEPTUNE cable offshore Vancouver Island, which supports five existing OBSs. These submarine cables themselves, alongside other private telecommunication cables, could be converted into dense seismic arrays via distributed acoustic sensing (DAS). Using existing data, we show that the cabled OBSs pass ShakeAlert requirements and are comparable to land stations in terms of data quality and triggering performance. We show that pilot DAS experiments also exhibit consistent noise characteristics across various candidate cables offshore Cascadia with sufficient sensitivity for early warning. Forward modeling suggests that incorporation of existing OBSs could improve the detection time of nearby hypocenters by 5-9 s. Further, if DAS were deployed on the first segments of the OOI cables, detection times of nearby hypocenters could improve by up to ~10 s. If DAS were deployed on the full extent of all 18 known offshore cables, nearly 50% of all theoretical offshore hypocenters could be detected more rapidly, by up to ~18s in some locations. Full ShakeAlert replays using new 3-D ground motion simulations of M8.7-9.2 Cascadia megathrust events show that offshore sensors could also improve ShakeAlert magnitude and location estimates. Assuming the distribution of existing OBSs, this could translate to ~40 s of additional warning time beyond improved detection time for nearby offshore hypocenters.

Session: Advancing Earthquake Early Warning: Science, Technology and Engagement in the U.S. and Beyond - I

Type: Oral

Room: Ballroom E

Date: 4/16/2026

Presentation Time: 08:30 AM (local time)

Presenting Author: Zoe Krauss

Student Presenter: No

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