An earthquake having an average body-wave magnitude of 5.1 occurred on Sunday, 27 July 1980 near Sharpsburg, Kentucky. The earthquake was widely felt throughout the Eastern United States and had a maximum Modified Mercalli intensity of VII in the epicentral region. The total felt area was approximately 673,000 km2. The well-constrained focal mechanism based on 128 P-wave first motions combined with other geological and seismological evidence indicates a fault plane striking N42°E, dipping 50°E with a slip vector 184° of the strike. This is a right-lateral strike-slip event with a small component of thrust. Isoseismal data strongly suggest a northeast-directed rupture. The strike is parallel to the trend of the West Hickman Creek fault zone but 30 km to the east of any known faults.