Real-time performance and new developments of the Propagation of Local Undamped Motion (PLUM) earthquake early warning algorithm for the West Coast, U.S.A.

Elizabeth S. Cochran, Jessie K. Saunders, Annemarie S. Baltay, Julian Bunn, Tim Clements, Debi Kilb, Sarah E. Minson, Colin O'Rourke, & Clara Yoon

Published September 11, 2022, SCEC Contribution #11896, 2022 SCEC Annual Meeting Poster #002

We present real-time performance and new developments of the Propagation of Local Undamped Motion (PLUM) earthquake early warning algorithm that is being tested prior to inclusion in the ShakeAlert system. The ShakeAlert System operates in California, Oregon, and Washington and is currently based on methods that estimate earthquake source parameters (magnitude and location). PLUM, alternatively, predicts expected ground motions from observed ground motions, obviating the need to estimate earthquake magnitude and location. The original PLUM algorithm was developed in Japan to address the deficiencies of source-based algorithms, such as missed or false alerts during complex sequences and limited-to-no warning times in the near-source region. PLUM detects an event when neighboring stations observe ground motions above defined trigger thresholds. PLUM begins predicting ground motion in pre-defined alert regions and then can be used to alert regions where ground motion exceeds a configurable threshold. The current PLUM detection method requires two stations to detect ground motions that exceed Modified Mercalli Intensity (MMI) values of 4.0 and 3.0, respectively. MMI values are derived from three-component velocity and acceleration data. Starting in July 2019, real-time testing of PLUM in the West Coast, U.S.A. has allowed for refinement of the algorithm specific to the ShakeAlert station configuration. During the real-time tests PLUM alert grids accurately covered areas of shaking for earthquakes of concern, including for the recent 2021 M 5.7 and M6.2 Petrolia, 2021 M6.0 Antelope Valley, and 2021 M5.3 Calipatria earthquakes. The median time from the earthquake origin to the initial PLUM event detection is ~6 seconds, which is on par and sometimes faster than the ShakeAlert system alerts. While PLUM performs well, we also examine whether extending PLUM to include a simple ground motion attenuation would allow for more targeted alerts. We thus present a preliminary version of the Attenuated ProPagation of Local Earthquake Shaking (APPLES) algorithm and compare the performance for a range of ground motion thresholds.

Key Words
earthquake early warning

Citation
Cochran, E. S., Saunders, J. K., Baltay, A. S., Bunn, J., Clements, T., Kilb, D., Minson, S. E., O'Rourke, C., & Yoon, C. (2022, 09). Real-time performance and new developments of the Propagation of Local Undamped Motion (PLUM) earthquake early warning algorithm for the West Coast, U.S.A.. Poster Presentation at 2022 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology