Over 600 earthquakes, with seismic intensity greater than IV on Modified Mercalli scale, which occurred between 1698 to 1983 in the southeastern United States, are used for the construction of regional seismotectonic provinces. The boundaries of these provinces are defined based on regional seismicity, gravity, magnetic, and geological data, as well as the concept of suspect terranes. Proposed boundaries of the seismotectonic provinces are nearly the same as those reported by Williams and Hatcher (1983) for the Appalachian miogeosyncline, the Piedmont and the Tallahassee-Suwannee Terranes, but they differ for the Avalon and the Brunswick Terranes. In addition, based on potential field data and seismicity pattern, a new seismotectonic province is also defined where the destructive Charleston earthquake of 1886, with maximum observed intensity of X, occurred. If this interpretation is correct, and, if it is assumed that there are no other major regional seismogenic sources based on historic seismicity, then the region with the highest seismic risk in the Coastal Plain is confined only to the Charleston seismotectonic province. Thus, the seismic risk of the remaining area of the Coastal Plain may not be as great as previously suggested.

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