Date of Award
Master of Science
Christine A Powell
Charles Adam Langston
Randel Tom Cox
Local earthquake tomography is used to investigate three dimensional velocity structure in the aftershock zone of the 2011 Mineral, VA, mainshock. A total of 5125 arrival times for 324 aftershocks recorded by 12 stations were used in the inversion. The inversion volume is small (22 x 20 x 16 km) with a block size of 1 x 1 x 1 km. Most of the aftershocks located at or below 2 km are associated with an NE trending, SE dipping anomalous velocity region with negative P-wave velocity (Vp) anomalies, positive S-wave velocity (Vs) anomalies, and Vp/Vs ratios as low as 1.54. We interpret the anomalous region as a highly quartz-rich sandstone or quartzite that accumulated in Paleozoic time along the passive margin of Laurentia and subsequently incorporated into the Piedmont Chopawamsic terrane during the Taconic orogeny. Two negative Vp and Vs anomalies are interpreted as metagraywacke and typical Chopawamsic rocks.
dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.
Islam, S M Ariful, "Mapping of Velocity Variations to Investigate Seismicity in the Upper Crust of the Central Virginia Seismic Zone, Virginia, USA" (2020). Electronic Theses and Dissertations. 2136.