Seismic Structure of the Charlotte and Carolina Slate Belts of Georgia and South Carolina

The seismic structure of the Charlotte and Carolina Slate belts was investigated by synthetic seismogram analysis. Using generalized ray theory and the Cagniardde Hoop method, synthetic seismograms were calculated for the first few seconds of reflected and refracted P-wave arrivals and compared with observed seismograms recorded within the area being studied. A model has been obtained of the detailed velocity structure of the crust which provider a good fit for two sets of seismograms up to an epicentral distance of 210 km. This model is in agreement with reflections at 11.0 to 11.5 sec two-way vertical reflection time seen on the COCORP Georgia lines 1 and 4, and is also in agreement with results from seismic refraction data assembled by Kean (1978). The model shows compressional wave velocities increasing from 5.1 km/sec to 6.0 km/sec in the upper 6 km of the crust. The average velocity of the crust is 6.0 km/sec and total crustal thickness is 33 km based on the analysis of reflections from the crust-mantle boundary, which is sharp in this area. There is a high velocity (6.6 km/sec) layer 4 km thick at the base of the crust.