The Campania, southern Italy, earthquakes of 1962 August 21

Summary Two earthquakes that occurred on 1962 August 21 in southern Italy, approximately 50 km NW of the destructive Campania‐Basilicata event of 1980 November 23 have been studied in order to investigate their geometry of faulting. Both events involved normal faulting; preferred focal mechanisms have one nodal plane that strikes NW parallel to the trend of the Apennines, and dips to the NE (strike 310°, dip 65°, rake – 130° for 18:09 event, and strike 310°, dip 65°, rake – 110° for 18:19 event). The 1962 events, like that of 1980, occurred at around 10 km depth beneath an intra‐Apennine sedimentary basin. A normal fault with the same orientation as the NE dipping nodal plane of the focal mechanisms has been observed on a commercial seismic reflection profile crossing this basin. It is suggested that this is the fault that moved in these events, and that repeated motion on this fault is responsible for the development of the basin and for the subsequent folding of Pliocene sedimentary rocks that outcrop in the area. Repetition of earthquakes in these areas suggests that intra‐Apennine sedimentary basins should be regarded as areas of high seismic hazard relative to surrounding localities.