Instantaneous and Delayed Triggering of Tremor Along the Parkfield-Cholame Section of San Andreas Fault
Description:
Surface waves of large distant earthquakes are capable of triggering deep tectonic tremor along the Parkfield-Cholame section of the San Andreas Fault. However, only in a few documented cases a major tremor episode lasted for a few days to weeks following a distant mainshock. Here we systematically examine how major tremor episodes near Cholame respond to dynamic stress changes from 115 M>5.5 earthquakes between 2001 and 2021 that are at least 200 km away from the broadband station BK.PKD. We first identify 99 major tremor sequences from a 20-year low-frequency earthquake tremor catalog and select 115 distant mainshocks with predicted peak dynamic stresses larger than 1 kPa. Next, for 57 selected mainshocks, we examine both the relative timing of tremor episodes and the tremor rate changes with respect to the last distant mainshock before the next major tremor episode. We find that the peak ground velocities of distant mainshocks do not determine whether a major tremor episode will likely follow. Instead, major tremor episodes near Cholame need to wait for a certain time before they are susceptible to dynamic triggering by distant mainshocks. This result is similar to previous findings for episodic tremor and slip events in Cascadia, suggesting that major tremor episodes near Cholame likely released most of the built-up tectonic stress, and a certain ‘re-charge’ time is needed before they can be remotely triggered. Our next step is to examine under what conditions distant earthquakes can trigger tremor instantaneously during their surface waves, and other factors that determine whether a major tremor episode is delayed triggered or not. In addition, we plan to use data-driven clustering methods to better define the start and end times of major tremor episodes, in order to better understand how they respond to distant earthquakes.
Session: New Observations and Modeling of Triggered Seismicity [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Zhigang Peng
Student Presenter: No
Invited Presentation:
Authors
Zhigang Peng Presenting Author Corresponding Author zpeng@gatech.edu Georgia Institute of Technology |
David Shelly dshelly@usgs.gov U.S. Geological Survey |
Taka’aki Taira taira@berkeley.edu University of California |
Haoran Meng menghr@sustech.edu.cn Southern University of Science and Technology |
Chastity Aiken chastity.aiken@ifremer.fr Ifremer |
Chang Ding cding64@gatech.edu Georgia Institute of Technology |
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Instantaneous and Delayed Triggering of Tremor Along the Parkfield-Cholame Section of San Andreas Fault
Category
New Observations and Modeling of Triggered Seismicity