Commentary: The role of geodetic algorithms for earthquake early warning in Cascadia

Geophysical Research Letters
By: , and 



The ShakeAlert earthquake early warning (EEW) system issues public alerts in California and will soon extend to Oregon and Washington. The Cascadia subduction zone presents significant new challenges and opportunities for EEW. Initial publications suggested that EEW algorithms based on Global Navigation Satellite System (GNSS) data could provide improved warning for intraslab events and dramatically improved warning for offshore megathrust events, both of which contribute significantly to hazard in Cascadia. We find that some expectations in these publications were unrealistic, and we demonstrate that in general geodetic algorithms would not produce timely warnings for intraslab events nor warning times of two minutes or more for severe shaking from megathrust earthquakes. Nonetheless, lessons from recent earthquakes in Japan and California, for which alerts from seismic algorithms suffered from magnitude saturation and high data latencies, demonstrate the urgent need for rigorous testing of geodetic EEW as a potential complement to seismic EEW.

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Publication type Article
Publication Subtype Journal Article
Title Commentary: The role of geodetic algorithms for earthquake early warning in Cascadia
Series title Geophysical Research Letters
DOI 10.1029/2020GL092324
Volume 48
Issue 6
Year Published 2021
Language English
Publisher American Geophysical Union
Contributing office(s) Earthquake Science Center
Description e2020GL092324, 8 p.
Country United States
State California, Oregon, Washington
Other Geospatial Cascadia subduction zone
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