55 Deciphering Active Tectonics and Seismic Hazard in Eastern North America

Sunday, 22 March 2020
8:00 AM - 12:00 PM
Regency Ballroom A

INTERPRETATION OF LINEAMENTS AND FAULTS NEAR SUMMERVILLE, SOUTH CAROLINA, USING LIDAR DATA AND PREVIOUSLY ACQUIRED SEISMIC-REFLECTION PROFILES: IMPLICATIONS FOR THE CAUSE OF THE 1886 CHARLESTON, SOUTH CAROLINA, EARTHQUAKE

Paper number: 55-12
Program: Theme Sessions
Time: 11:35 AM – 11:55 AM

Authors

Abstract

LiDAR data recently acquired near Summerville, SC, reveals numerous lineaments trending in various directions across the Coastal Pain, especially near the Middleton Place-Summerville seismic zone. A Pleistocene beach ridge is dextrally offset ~325 m north of Summerville along the trend of the Woodstock fault, indicating that this fault has locally ruptured the surface multiple times in the past. Two NE-SW trending lineaments near Middleton Place (Middleton Place and Otranto lineaments) coincide with faults interpreted from previously acquired seismic-reflection profiles, suggesting that these lineaments are surface expressions of faults. The Otranto lineament bisects the northeastern lobe of Earle Sloan’s isoseismals of the 1886 Charleston earthquake, suggesting that the fault along this lineament may have ruptured the ground surface in 1886. Numerous circular gentle depressions ~50-100 m in diameter are also visible on the LiDAR imagery throughout the area, including the area well to the northwest of Summerville. These gentle depressions are likely surface expressions of ancient sand blows from past earthquakes. Lastly, an aeromagnetic image and the numerous seismic-reflection profiles previously acquired by the University of South Carolina, Virginia Tech, and the USGS support the existence of a continuous Woodstock fault with a gentle ~10° bend near the Ashley River.

Geological Society of America Abstracts with Programs. Vol. 52, No. 2

doi: 10.1130/abs/2020SE-345392

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