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Event Detection and Foreshock Characterization Using the Ridgecrest and San Jacinto Dense Nodal Array Data

Session: New Insights Into the Preparatory Phase of Earthquakes From Tectonic, Field and Lab Experiments I

Type: Oral

Date: 4/19/2021

Presentation Time: 10:30 AM Pacific

Description: 

Understanding foreshocks is essential for deciphering the earthquake nucleation process and informing earthquake probabilistic forecasting. Using P-waves from catalog earthquakes as templates, we apply waveform auto-correlation to search for foreshocks adjacent to the mainshocks within the 100 s before each event. We detect immediate foreshocks for 292 earthquakes in the Ridgecrest sequence, with magnitudes ranging from 0.9 to 5.4. Because these foreshocks occur very close in space and time to the mainshock and have similar waveforms to the mainshock P-wave, they may be part of a nucleation process for the mainshock rupture initiation. However, because our observed precursory signal attributes do not scale with mainshock magnitude, the sequences appear to evolve stochastically. To better evaluate the role of foreshocks in the earthquake preparation process, we plan to develop techniques based on multichannel cross-correlation to detect small-magnitude earthquakes. The analysis will be performed on the 2019 Ridgecrest and 2014 San Jacinto dense nodal-array datasets, aiming to characterize foreshock statistics and properties of earthquake rupture development in both the Ridgecrest region and within an active strand of the San Jacinto Fault.

Presenting Author: Haoran Meng

Student Presenter: No

Authors