The Irpinia Fault is a normal fault system in the southern Apennines of Italy, in the Campania region inland from Naples. It reflects the extensional tectonics that stretch the crust along the mountain chain's axis, where blocks drop down along steeply dipping fault planes rather than sliding sideways or thrusting over one another.
The fault zone consists of several linked segments that can rupture in complex, multi-stage events. This extensional regime produces relatively shallow earthquakes capable of intense local ground motion, and the mountainous, densely settled terrain of Irpinia amplifies both the shaking and its human cost.
The devastating 1980 Irpinia earthquake (magnitude 6.9) killed roughly 2,700 people, injured thousands and left hundreds of thousands homeless across Campania and Basilicata. Its complex rupture, unfolding in distinct sub-events over tens of seconds, became a landmark case study in earthquake seismology and reshaped Italy's civil-protection and building-code policies.