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Small Aperture Seismic Arrays for Offshore Out-of-Network Events

Description: 

Two small-aperture (~350 m) five-element seismic arrays of accelerometers were installed on southwestern Vancouver Island, British Columbia, Canada, as part of a pilot study related to Earthquake Early Warning (EEW) in Canada. The location uncertainty for offshore (out-of-network) earthquakes remains an order of magnitude greater than for most within-network events . Small-aperture arrays installed within existing EEW networks have been shown to improve EEW performance for out-of-network earthquakes through robust back-azimuth and slowness vector determination [Eisermann et al., 2019; Netanel et al., 2021], and are independent of regional velocity model assumptions. To test the ability of both standalone and network-integrated arrays to (1) reduce earthquake location uncertainty for offshore events within 250 km of the coast and (2) improve EEW alerting timeliness to coastal communities, we deployed two small-aperture arrays along a coastline known for its high seismic and tsunamigenic hazard. Both arrays are located less than 1 km from the Pacific Coast and are approximately 55 km apart, to target offshore seismicity. The first array near Tofino (aperture 361 m) has a minimum element spacing of 82 m, and the array near Bamfield (aperture 338 m) has a minimum element spacing of 76 m. Real-time, low-noise, high-gain (1/4g) TitanSMA accelerometers were installed in single-story buildings with existing power and various communications infrastructure. Each element installation has a standalone GPS receiver for timing. Preliminary results from these arrays will be presented and their utility in the context of the existing Canadian EEW network discussed.

Session: Network Seismology: Recent Developments, Challenges and Lessons Learned - II

Type: Oral

Date: 5/1/2024

Presentation Time: 05:00 PM (local time)

Presenting Author: H.K. Claire

Student Presenter: No

Invited Presentation: 

Authors