ElarmS/EPIC Earthquake Early Warning System: 2018-2019 Development and Performance

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

The ElarmS Earthquake Early Warning System (EEWS) is a point-source, network-based EEWS that has been under development since early 2006. ElarmS was one of the original US West Coast ShakeAlert algorithms. Recently, significant modifications were made to the code that resulted in ElarmS version 3.0 (E3), which was deployed on the ShakeAlert production system on January 25, 2018. Because of its excellent performance as part of the ShakeAlert system, ElarmS was chosen as the basis for EPIC (Earthquake Point-Source Integrated Code), the only point-source algorithm that ShakeAlert will use in the future. EPIC replaced E3 on the ShakeAlert production system on September 28, 2018.

Since January 2018, E3 and EPIC have performed well, alerting for 18 of the 22 M≥4 earthquakes within the West Coast reporting boundary. Of the four missed events, all were 4≤M≤4.7 at the edges of the alerting boundary (two in Baja California, one offshore Canada, and one offshore Northern California). Improvements to the system have significantly reduced the number of false alerts, however, some false alerts were still generated by the algorithms. Some false alerts were due to bugs in the code, which have since been fixed, but others were caused by teleseismic, noisy, and spurious triggers. Preventing alerts from triggers like these remains a high-priority goal for the ElarmS/EPIC team.

In this presentation, we will review modifications that were made to E3 to create the new algorithm EPIC. We will discuss the performance of E3 and EPIC for 2018-2019 and the expected performance of the algorithm based on historic replays. Finally, we will highlight new research focused on optimizing alerts and preventing false alerts.

Presenting Author: Angela Chung

Authors