A study of neotectonics in the southeastern United States was carried out by examining a variety of parameters, including the state of stress, pattern of seismicity, ground deformation, and estimation of recurrence rate for larger events. The direction of maximum horizontal stress (S_nmax) was found to be uniform over the region, oriented in an ENE-WSW direction, and due to plate-tectonic forces. The current, historic, and prehistoric seismicity was found to occur in local clusters that displayed spatial stationarity over the historical period (300 yr). Ground deformation inferred from relev-eling, geoarcheological, and shallow sedimentary data was found to occur both on a regional and a local scale, the rates of deformation varying over the region. Statistical and paleoseismological data suggest a recurrence period of about 1,000 to 2,000 yr for the larger events in the Charleston, South Carolina, area.

These observations lead to the conclusion that neotectonic activity is episodic and is due to the interaction of a uniform stress field with local, preexisting zones of weakness. In the current episode of neotectonic activity (>300 yr and < 2 m.y.), most of the dominant patterns of seismicity display spatial stationarity; thus, the current distribution of activity can be used for assessing seismic hazards.