A systematic search of contemporary newspapers in South Carolina, North Carolina, Georgia and eastern Tennessee during the 1886--1889 (inclusive) aftershock sequence of the August 31, 1886 earthquake near Charleston, South Carolina has provided more than 3000 intensity reports for 522 earthquakes as compared to 144 previously known earthquakes for the same period. Of these 144 events, 138 were felt in Charleston/Summerville and had been assigned epicenters in that area. In contrast the new data provide 112 well-constrained macroseismic epicenters. The 1886--1889 seismicity is characterized by a linear relation between log frequency and magnitude with a slope b≈1, a temporal decay of earthquake frequency proportional to time -1, and a low level of seismicity prior to the main shock. These are frequently observed characteristics of aftershock sequences. By 1889, the level of seismicity had decreased more than 2 orders of magnitude, reaching approximately the current level in the same area. The 1886--1889 epicenter delineate a large aftershock zone that extends northwest about 250 km across Appalachian strike from the coast into the Piedmont and at least 100 km along strike near the Fall Line of South Carolina and Georgia.

An abrupt change in stress and/or effective strength is required over this zone. If this change can only occur in the near field of a single fault dislocation, this fault must be larger horizontally than the thickness of the seismogenic zone by an order of magnitude and must be shallow dipping. The correlation between the area of intensity VIII in the main shock with the area of large aftershocks is consistent with this hypothesis. The lack of a major fault affecting the post-Upper Jurassic onlap sediments also favors a shallow dipping active fault, possibly a Paleozoic-Mesozoic southeasterly dipping fault or detachment that may outcrop northwest of the aftershock zone. The 1886--1889 aftershocks occupy the same area as the South Carolina-Georgia seismic zone as defined by recent seismicity. The portion of this zone in the Piedmont is the only area of the southeastern United States where reservoir-induced seismicity is unambiguously recognized.Seismicity elsewhere in the Southeast, such as in the Virginia seismic zone, is deeper and apparently unrelated to reservoir loading. Thus, the 1886--1889 aftershock zone is currently manifested by a zone of seismicity with unique characteristics. ¿ American Geophysical Union 1987