Analysis and Possible Implications of Recent California Earthquakes

John B. Rundle, Lisa Grant Ludwig, Robert Zinke, Andrea Donnellan, & Geoffrey Fox

Published September 8, 2024, SCEC Contribution #13702, 2024 SCEC Annual Meeting Poster #202 (PDF)

On August 6, 2024 a magnitude M5.2 earthquake occurred 24 km southwest of Lamont, CA, north of the intersection of the Garlock fault with the San Andreas fault in the area of the big bend and the transverse ranges. Then, on August 12, 2024, a magnitude M4.4 earthquake occurred 4 km south-southeast of Highland Park, CA, within the Los Angeles basin. Aftershocks continue from both events. In a proposal submitted to the NASA EVS call in April 2023, a series of UAVSAR flight lines were defined in California, and a forecast of earthquake probablities was stated, based upon the NTW (Natural Time Weibull) method. The first of these two events fulfills the forecast in the proposal. In related studies, earthquake nowcasting is a relatively new method that employs a simple 2-parameter filter on the observed monthly seismic rate of small earthquakes, and uses machine learning to improve the nowcast filter, and these methods are being actively developed in a variety of ongoing research projects (Fox et al., 2022; Rundle et al., 2024a,b). Rundle et al. (2024a,b) also discuss a new model "QuakeGPT" that uses stochastic earthquake simulations to train a science transformer model, an attention-based technology similar to that which underlies ChatGPT (Rundle et al., 2024a,b). With respect to the existing earthquake nowcasting technology, we have computed examples of videos that illustrate the advantages of following the change in earthquake risk through time. In the southern California video, the recent earthquakes in southern California are coincident with an enhanced spatial and temporal probability of a significant earthquake (M6.75) in southern California. In the southern California area, the spatial probability density is in the vicinity of the Lamont earthquake, and generally lies along the Garlock fault, stretching from the epicentral region of the 2019 Ridgecrest earthquake, towards the intersection of the Garlock fault with the San Andreas. In the California video, the enhanced probability is not as obvious. We plan to closely monitor the incoming data with these methods, and continue to evaluate the results for their importance and significance.
Videos: https://rundle.physics.ucdavis.edu/Movies/SouthernCalifornia.mp4
https://rundle.physics.ucdavis.edu/Movies/California.mp4

Key Words
Nowcasting, Machine Learning, AI

Citation
Rundle, J. B., Grant Ludwig, L., Zinke, R., Donnellan, A., & Fox, G. (2024, 09). Analysis and Possible Implications of Recent California Earthquakes. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)