Mapping of Velocity Variations to Investigate Seismicity in the Upper Crust of the Central Virginia Seismic Zone, Virginia, USA

Identifier

6647

Author

S M Ariful Islam

Date

2020

Document Type

Thesis

Degree Name

Master of Science

Major

Earth Sciences

Concentration

Geophysics

Committee Chair

Christine A Powell

Committee Member

Charles Adam Langston

Committee Member

Randel Tom Cox

Abstract

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.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

Recommended Citation

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.
https://digitalcommons.memphis.edu/etd/2136