Induced seismicity and earthquake prediction studies in South Carolina

Abstract

This report presents data on Induced seismicity studies in South Carolina up to September 1979.The low level seismicity at Lake Oocassee was interrupted by a MbL 3.7 earthquake on August 25, 1979 (9:31 PM local time). This intensity VI event was the largest event to occur at Lake Oocassee and it was widely felt. Its focal mechanism revealed a large component of normal faulting.Comparison with earlier focal mechanisms and stress measurements suggests that only a thin veneer (^ 1.5 km) of the near surface rocks are highly stressed.In addition to the routine analysis of seismicity data at Monticello reservoir, we analysed in detail 180 events recorded on analog tapes between July and December 1978. This detailed analysis revealed that the seismicity is shallow (< 2 km), appears to spread in discrete jumps and occurs along existing joint and fracture planes by the diffusion of pore pressure to hypocentral depths.

In situ studies of velocity in fractured crystalline rocks

“…Monticello Reservoir is the site of considerable reservoir-induced seismicity [see Talwani et, al., 1980]. Most of the earthquakes in the vicinity of the reservoir are small (M<2) events at extremely shallow depth (< 1-2 km).…”

Geological studies in an area of induced seismicity at Monticello Reservoir, South Carolina

“…This increased level of seismic activity has continued intermittently to the present. Lake Monticello-is one of the most thoroughly documented cases of induced seismicity in the United States (Due and others, 1978;Talwani and others, 1978;Talwani, 1979;Talwani and others, 1980). The U.S. Geological Survey, the National Science Foundation, and the South Carolina Electric and Gas Company are supporting an intense research effort to understand the causes and controls of the seismic activity at Lake Monticello.…”

Natural Phenomena Hazards Design Criteria and Other Characterization Information for the MFFF at SRS

“…Varying velocity models have been developed using 20 years of seismic refraction surveys completed throughout South Carolina (Ref. 279,309). A total of five velocity models covering the entire state of South Carolina were developed from this data.…”