Real-Time Performance of the Plum Earthquake Early Warning Algorithm for Western U.S.
Session: Earthquake Early Warning Live in California! Current Status and Challenges II
Type: Oral
Date: 4/23/2021
Presentation Time: 02:15 PM Pacific
Description:
We report results from running the Propagation of Local Undamped Motion (PLUM) EEW algorithm for one-year (2019-08-15 to 2020-08-14) on real-time data from stations in the ShakeAlert earthquake early warning (EEW) System for the West Coast, USA. Testing EEW algorithms on real-time data can uncover issues that offline data tests cannot. In contrast to current ShakeAlert algorithms, PLUM is ground motion based and designed to issue alerts when ground motions exceed a specified intensity. PLUM issues an event detection when two or more neighboring stations report ground motions above Modified Mercalli Intensity (MMI) 4 and 2.5 for the first and neighbor stations, respectively. PLUM then forward-predicts the observed ground motions to sites within 30 km of any triggering stations, which are used to determine the alerting region. During the one-year test period, PLUM detected 62 events, of which five were M5+. PLUM missed two M5+ events, but both were theoretically not detectable by PLUM because they were either offshore or at the edge of the network. PLUM did detect the 2020-03-09 M5.8 offshore Petrolia earthquake, which the operational ShakeAlert System missed. Of the 62 earthquakes detected by PLUM, the elapsed time between the earthquake origin time and the PLUM detection (not including alert dissemination that might take ~5s) ranged from 2-27s, with a mean elapsed time of 6.2±5.1s and median elapsed time of 4.8s. PLUM’s trigger times are consistent with a seismic wave speed of 3±1.3 km/second, suggesting most of the triggers occurred during the S-wave. An approximate earthquake location can be derived with a weighting scheme using the station’s MMI values and trigger times, which nets median and mean location errors of 4.8 km and 9.7 km, respectively, which are on par or smaller than ShakeAlert errors. We conclude PLUM can successfully identify the occurrence of strong shaking and is a promising candidate for integration into the U.S. ShakeAlert EEW System.
Presenting Author: Deborah Kilb
Student Presenter: No
Authors
Deborah Kilb Presenting Author Corresponding Author dkilb@ucsd.edu Scripps Institution of Oceanography, University of California, San Diego |
Elizabeth Cochran ecochran@usgs.gov U.S. Geological Survey |
Julian Bunn julian.bunn@caltech.edu Caltech and U.S. Geological Survey |
Jessie Saunders jksaunders@usgs.gov U.S. Geological Survey |
Sarah Minson sminson@usgs.gov U.S. Geological Survey |
Annemarie Baltay abaltay@usgs.gov U.S. Geological Survey |
Colin O’Rourke corourke@usgs.gov U.S. Geological Survey |
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Real-Time Performance of the Plum Earthquake Early Warning Algorithm for Western U.S.
Category
Earthquake Early Warning Live in California! Current Status and Challenges