Seismological Research Letters; July/August 2006; v. 77; no. 4;
p. 494-504; DOI: 10.1785/gssrl.77.4.494
© 2006 Seismological Society of America
Fault Orientation in the Eastern Tennessee Seismic Zone: A Study Using the Double-Difference Earthquake Location Algorithm
We use the double-difference earthquake location algorithm to relocate
approximately 1,000 earthquakes in the eastern Tennessee seismic zone (ETSZ).
We examine the earthquake hypocenter relocations in an effort to resolve fault
orientations and thereby gain insights into the tectonics of the seismic zone.
The analysis involves visual comparison of three-dimensional perspective plots
of the hypocenter relocations oriented according to focal mechanism nodal
planes derived from events within several clusters of earthquakes.
Relocations in the central, most seismically active, portion of the ETSZ
indicate a diffuse west-striking, north-dipping zone of hypocenters. The
orientation of this zone of hypocenters is consistent with structure imaged by
a previous seismic reflection profile that shows a reflective mid-to-upper
crust with apparent dips of approximately 35° to the north. Relocation of
a smaller cluster of earthquakes near the Tennessee-North Carolina border
suggests a steeply dipping northwest trending fault in that area.
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