Aftershocks illuminate the 2011 Mineral, Virginia, earthquake causative fault zone and nearby active faults

Special Paper of the Geological Society of America
By: , and 

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Abstract

Deployment of temporary seismic stations after the 2011 Mineral, Virginia (USA), earthquake produced a well-recorded aftershock sequence. The majority of aftershocks are in a tabular cluster that delineates the previously unknown Quail fault zone. Quail fault zone aftershocks range from ~3 to 8 km in depth and are in a 1-km-thick zone striking ~036° and dipping ~50°SE, consistent with a 028°, 50°SE main-shock nodal plane having mostly reverse slip. This cluster extends ~10 km along strike. The Quail fault zone projects to the surface in gneiss of the Ordovician Chopawamsic Formation just southeast of the Ordovician–Silurian Ellisville Granodiorite pluton tail. The following three clusters of shallow (<3 km) aftershocks illuminate other faults. (1) An elongate cluster of early aftershocks, ~10 km east of the Quail fault zone, extends 8 km from Fredericks Hall, strikes ~035°–039°, and appears to be roughly vertical. The Fredericks Hall fault may be a strand or splay of the older Lakeside fault zone, which to the south spans a width of several kilometers. (2) A cluster of later aftershocks ~3 km northeast of Cuckoo delineates a fault near the eastern contact of the Ordovician Quantico Formation. (3) An elongate cluster of late aftershocks ~1 km northwest of the Quail fault zone aftershock cluster delineates the northwest fault (described herein), which is temporally distinct, dips more steeply, and has a more northeastward strike. Some aftershock-illuminated faults coincide with preexisting units or structures evident from radiometric anomalies, suggesting tectonic inheritance or reactivation.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Aftershocks illuminate the 2011 Mineral, Virginia, earthquake causative fault zone and nearby active faults
Series title Special Paper of the Geological Society of America
DOI 10.1130/2015.2509(14)
Volume 509
Year Published 2015
Language English
Publisher Geological Society of America
Contributing office(s) Eastern Geology and Paleoclimate Science Center, Eastern Mineral and Environmental Resources Science Center
Description 19 p.
First page 253
Last page 271
Country United States
State Virginia
City Mineral
Online Only (Y/N) N
Additional Online Files (Y/N) N