Seismogenic structures in the central Virginia seismic zone

Journal Article · Mon Aug 01 00:00:00 EDT 1988 · Geology; (United States)

OSTI ID:6799527

Coruh, C; Bollinger, G A; Costain, J K

A correlation between earthquake hypocenters and seismic reflection data in central Virginia has become apparent on an automatic line drawing (ALD) display of seismic reflection data. With the reprocessed Virginia I-64 reflection Vibroseis data extended to 14 s, reflectors are imaged from the lower crust as well as from the upper crust. Specifically, the improved resolution and data quality of ALDs have produced an image of an antiformal structure bounded by mid-crustal reflections on the bottom and by major thrusts at the top. The reflections that define the roof of the antiform are most prominent from about 6 s (18 km) on the east near Richmond under the Coastal Plain sediments, to 1-1.3 s (3-4 km) between Richmond and Charlottesville, and to 3.5 s (10.5 km) on the west. Seismic signatures that can be followed downward from the surface between Charlottesville and Richmond appear to be truncated at the roof of the antiform. The dominant reflections that define the roof correlate with the seismic signature of the transported Taconic suture on the west flank and mylonites on the east flank. The distribution of hypocenters in the area shows an excellent correlation with the westward-dipping reflections that form the roof of the antiform on its western flank. Earthquake activity in this locale may be related to reactivation of the thrusts defining the roof and/or faults above the antiformal structure; however, distribution of the easternmost and deepest set of hypocenters appears to be related to an extensive near-vertical diabase dike swarm of Mesozoic age.

• Research Organization: Virginia Polytechnic Institute and State Univ., Blacksburg (USA)
• OSTI ID: 6799527
• Journal Information: Geology; (United States), Vol. 16:8
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
EARTHQUAKES
CORRELATIONS
SEISMIC SURVEYS
VIRGINIA
DATA ANALYSIS
DISTRIBUTION
GEOLOGIC FAULTS
GEOLOGIC STRUCTURES
HYPOCENTERS
SEISMIC WAVES
SEISMICITY
FEDERAL REGION III
GEOLOGIC FRACTURES
GEOPHYSICAL SURVEYS
NORTH AMERICA
SEISMIC EVENTS
SURVEYS
USA
580201* - Geophysics- Seismology & Tectonics- (1980-1989)