Tectonic Inheritance and Seismicity in the Southeastern United States Rifted Margin
Abstract
The Southeastern United States has a rich tectonic history that includes the growth of the Southern Appalachians culminating in the Alleghanian orogeny, formation of the Triassic South Georgia Rift, and ultimately the breakup of Pangea and formation of the Atlantic rifted margin. Recent wide-angle seismic velocity models and receiver functions in the Southeastern US provide new constraints on orogenic and extensional structures and indicate that the main orogenic structures in the region influenced later rifting. The extent to which present day seismicity exploits ancient orogenic and extensional structures in the southeastern US and in other intraplate settings is debated, in part due to the limited number of tectonic earthquakes that can be detected using seismic networks typically present in the region.
In 2012-2014, the combined SESAME array and US Transportable Array provided an unprecedented, dense seismic network with the potential to detect and locate smaller seismic events. In this talk, we will describe preliminary observations of regional patterns in seismic activity and investigate potential controls on that seismicity. We apply detection, association, and location algorithms to identify over 300 events in the two year period. Preliminary earthquake locations concentrate in the crust at the Eastern Tennessee Seismic Zone and near the Higgins-Zietz magnetic boundary, a suture zone that localized Appalachian orogenesis and subsequent rifting. One challenge of characterizing seismicity in this region is distinguishing earthquakes from abundant quarry blasts that often cluster near quarries northwest of the fall line. We will describe strategies to categorize these events as industrial or tectonic-related, and use the results to better characterize patterns of seismicity in relation to existing tectonic structures.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T13G0275M
- Keywords:
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- 1021 Composition of the oceanic crust;
- GEOCHEMISTRY;
- 8102 Continental contractional orogenic belts and inversion tectonics;
- TECTONOPHYSICS;
- 8104 Continental margins: convergent;
- TECTONOPHYSICS;
- 8105 Continental margins: divergent;
- TECTONOPHYSICS