Understanding the Focal Mechanism Distribution of Microseismicity in the Source Region of the 1886 M 7 South Carolina Earthquake
Description:
In Late August 1886, the East Coast of United States suffered the largest and most damaging magnitude ~7 earthquake near Summerville in South Carolina. However, there remains no evidence of surface faulting, leading to the puzzling nature of the fault mechanism responsible for this important event. Presently, the neighborhood near Summerville still experiences ongoing microseismicity, which has been inferred as the aftershock sequence of the 1886 main shock. Therefore, monitoring modern seismic activities can help to better define the source fault for the 1886 event, and allow for better evaluation of the seismic hazard in this region, as well as serving as a potential analogue for east coast intraplate seismicity. Previous studies (Dura-Gomez and Talwani, 2009), give an inference to the existence of multiple faults within this region. However, results from a 2011-2012 deployment of an 8-station seismic network (Chapman et al., 2016) hypothesized a southwest striking and west-dipping zone of modern seismicity. Starting from May 2021, a temporary 19-station short-period network deployment was deployed in Summerville to better analyze spatial variations in microseismicity (Jaume et al., 2021). Preliminary results from microseismicity relocation revealed a south-striking west-dipping zone in the southern seismicity cluster and a north-south striking near-vertical plane further north, indicating complex patterns of stress and faulting styles in the region (Chen et al., 2023). In this study, we apply a newly developed deep-learning polarity picker (Zhai et al., 2021) to measure the P-wave first motion polarities of 181 events detected from one year of continuous data from this deployment. Consequently, these polarity results will be combined with the measured S/P amplitude ratios to determine their focal mechanisms. In addition, we plan to re-analyze the events recorded by the previous deployment (Chapman et al., 2016), with the expectation of better quantifying the fault structures and subsurface stress fields in this region.
Session: Tectonics and Seismicity of Stable Continental Interiors [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Oluwaseyifunmi E. Adeboboye
Student Presenter: Yes
Invited Presentation:
Authors
Oluwaseyifunmi Adeboboye Presenting Author Corresponding Author oadeboboye3@gatech.edu Georgia Institute of Technology |
Zhigang Peng zpeng@gatech.edu Georgia Institute of Technology |
Miguel Neves mjgfgn3@gatech.edu Georgia Institute of Technology |
Qiushi Zhai qzhai@caltech.edu California Institute of Technology |
William Chen chen6430@umn.edu University of Minnesota |
Steven Jaume jaumes@cofc.edu College of Charleston |
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Understanding the Focal Mechanism Distribution of Microseismicity in the Source Region of the 1886 M 7 South Carolina Earthquake
Category
Tectonics and Seismicity of Stable Continental Interiors