Status of ShakeAlert and G-FAST in the Pacific Northwest

John E. Vidale, Brendan W. Crowell, J R. Hartog, Paul Bodin, Victor C. Kress, & Ben Baker

Submitted August 15, 2016, SCEC Contribution #6871, 2016 SCEC Annual Meeting Poster #237

Here, we evaluate the real-time and historical performance of the ElarmS‐2 algorithm in the Pacific Northwest. Real‐time and pre-recorded seismic data from Oregon, California, and Washington in the United States and British Columbia in Canada have been used.

The prototype ShakeAlert system in the Pacific Northwest has been operational since February 2013 with ElarmS-2. In February 2015, a select group of local stakeholders began receiving alerts. We have made several adjustments that make the ElarmS‐2 algorithm less likely to falsely report multiple alerts for earthquakes. Replaying of past earthquakes shows that the new settings improve the algorithm’s behavior for edge cases while not degrading previously well‐constrained solutions within the dense part of the network. We expect few false alerts, and none that would predict significant shaking anywhere in our region. Even though ElarmS‐2 assumes a fixed earthquake depth, the epicenter and magnitude estimates are accurate enough to provide good predictions of shaking intensities even for 50-km deep events.

In addition, the G-FAST GPS-based earthquake early warning module has been in testing since September 2015. Starting in early 2016, an Amazon Catalyst funded effort has been under way to optimize and integrate G-FAST into ShakeAlert. We have also created a test system that allows us to replay past and synthetic earthquakes to identify problems with both the network architecture and the algorithms, with options for altering latency, data completeness, noise, and epicentral location. Events replayed through the test system include the 2001 Mw 6.8 Nisqually, 2010 Mw 9.0 Tohoku-oki, 2010 Mw 8.8 Maule, 2014 Mw 8.2 Iquique and the 2015 Mw 8.3 Iquique earthquakes, and we report the performance of G-FAST in rapidly modeling these events.

Key Words
Earthquake early warning

Vidale, J. E., Crowell, B. W., Hartog, J. R., Bodin, P., Kress, V. C., & Baker, B. (2016, 08). Status of ShakeAlert and G-FAST in the Pacific Northwest. Poster Presentation at 2016 SCEC Annual Meeting.

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