Preliminary Results from a Dense Short-Period Seismic Deployment around the Source Zone of the 1886 M 7 South Carolina Earthquake
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1.
University of Minnesota
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2.
Georgia Institute of Technology
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3.
California Institute of Technology
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4.
Applied Research Associates (United States)
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5.
College of Charleston
Abstract
The 1886 magnitude ∼7 Summerville, South Carolina, earthquake was the largest recorded on the east coast of the United States. A better understanding of this earthquake would allow for an improved evaluation of the intraplate seismic hazard in this region. However, its source fault structure remains unclear. Starting in May 2021, a temporary 19-station short-period seismic network was deployed in the Summerville region. Here, we present our scientific motivation, station geometry, and quality of the recorded seismic data. We also show preliminary results of microearthquake detections and relocations using recordings from both our temporary and four permanent stations in the region. Starting with 52 template events, including two magnitude ∼3 events on 27 September 2021, we perform a matched filter detection with the one year of continuous data, resulting in a catalog of 181 total events. We then determine precise relative locations of a portion of these events using differential travel-time relocation methods, and compare the results with relocation results of 269 events from a previous seismic deployment in 2011–2012. We also determine focal mechanism solutions for three events from 27 September 2021 with magnitudes 2.0, 3.1, and 3.3, and infer their fault planes. Our relocation results show a south-striking west-dipping zone in the southern seismicity cluster, which is consistent with the thrust focal mechanism of the magnitude 3.3 earthquake on 27 September 2021 and results from the previous study based on the temporary deployment in 2011–2012. In comparison, the magnitudes 3.1 and 2.0 events likely occur on a north–south-striking right-lateral strike-slip fault further north, indicating complex patterns of stress and faulting styles in the region.
Copyright and License
© 2023 Seismological Society of America.
Acknowledgement
The authors thank Derrick Murekezi, Maggie Hanley, and Steve Maloney for helping with the initial seismic deployment in 2021. The authors thank Martin Chapman and Qimin Wu for sharing the phase picks and relocated catalog from the 2011–2012 deployment, and information used to reproduce their figure 1 in Chapman et al. (2016). The authors would also like to thank many public and private owners in Summerville for allowing them to deploy seismic stations in their properties. This project is supported by U.S. Geological Survey’s (USGS) National Earthquake Hazards Reduction Program (NEHRP) Grant Numbers G21AP10108 (Miguel Neves, Qiushi Zhai, Clara Daniels, and Zhigang Peng) and G21AP10093 (Steven Jaume). Miguel Neves is also supported by a Ph.D. fellowship from the Portuguese research foundation Fundação para a Ciência e a Tecnologia (FCT), Grant Number SFRH/BD/139033/2018. William Chen is supported by the Incorporated Research Institutions for Seismology (IRIS) Summer Internship program.
Data Availability
Seismic data recorded by the YH network can be downloaded from Incorporated Research Institutions for Seismology Data Management Center (IRIS DMC) at https://ds.iris.edu/mda/YH/#YH_2021-04-26_2023-03-31 (last accessed June 2022). Currently, the data are in restrictive mode and will be openly available after 2 yr of the experiment. Station YH.WSCT is openly available at IRIS DMC, and its helicorder can be viewed at http://folkworm.ceri.memphis.edu/heli_temp/ (last accessed June 2022). Most figures are generated using Generic Mapping Tools (GMT; Wessel et al., 2019) and MATLAB (www.mathworks.com/products/matlab, last accessed June 2023). We use ObsPy (Beyreuther et al., 2010) to make the probabilistic power spectral density (PPSD) plots in Figure 4. The earthquake catalogs compiled in this study and the respective description are included in the supplemental material.
Supplemental Material
Supplementary Data (DOCX)
Supplementary Movie s1 (ZIP)
Supplementary s1 (TXT)
Supplementary s2 (TXT)
Supplementary s3 (TXT)
Supplementary s4 (TXT)
Supplementary s5 (TXT)
Supplementary s6 (TXT)
Supplementary s7 (TXT)
Supplementary s8 (TXT)
Supplementary s10 (TXT)
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Additional details
- United States Geological Survey
- G21AP10108
- United States Geological Survey
- G21AP10093
- Fundação para a Ciência e Tecnologia
- SFRH/BD/139033/2018
- Incorporated Research Institutions For Seismology
- Available
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2023-07-18First Online
- Caltech groups
- Division of Geological and Planetary Sciences, Seismological Laboratory
- Publication Status
- Published