The Beltana earthquake of 29 December 1983 occurred in the North Flinders Ranges, one of the most seismically active parts of South Australia. Although earthquakes in this region may be associated with a north‐south chain of diapirs, the structural relationship between the earthquake and the diapirs is not clear. The main Beltana earthquake was associated with two foreshocks and 16 aftershocks. The trend of this sequence (319 ± 4°) is consistent with the focal mechansim, which indicates a northwest‐trending left‐lateral strike‐slip fault caused by eastwest compression. The axis of maximum compression is similar to those obtained from six other South Australian earthquakes (McCue & Sutton 1979; Singh 1985). However, the trend of the sequence does not appear to relate to the surface geometry of the Beltana Diapir, which is intersected by the earthquake sequence. The main earthquake was recorded throughout the Australian continent. A least squares analysis of the first arrivals gives a Pnvelocity of 8.28 ± 0.02 km/s in the 170–1250 km range, and a velocity of 8.82 + 0.07 km/s, beyond 1400 km. These results are consistent with data obtained earlier (Denhamet al1972) from the Ord River explosions for central and Western Australia. The magnitudes of the main earthquake were 5.1 mband 4.4 MLand seismic moment was about 1 x 1016N‐m. The earthquake was felt over an area of about 15 000 km2. A maximum intensity of MM VI was experienced in the Beltana/Parachilna region, where several reports were received of wall and ceiling plaster being cracked and displaced.