1997 Umbria and Marche earthquakes
Photo of the partially collapsed ceiling vault of the Basilica of Saint Francis of Assisi after the earthquake | |
| UTC time | 1997-09-26 09:40:26 |
|---|---|
| ISC event | 1043512 |
| USGS-ANSS | ComCat |
| Local date | 26 September 1997 |
| Local time | 11:40 |
| Magnitude | 6.0 Mw |
| Depth | 10 km (6.2 mi) |
| Epicenter | 43°05′02″N 12°48′43″E / 43.084°N 12.812°E |
| Areas affected | Italy (Umbria, Marche) |
| Max. intensity | MMI X (Extreme) |
| Casualties | 11 dead 100 injured |
The 1997 Umbria and Marche earthquakes occurred in the regions of Umbria and Marche, central Italy over a period of several months from September 1997 to April 1998. It consisted of eight earthquakes with magnitudes greater than Mw5. The first of the larger shocks, which measured Mw 5.7, occurred at 02:33 CEST (00:33 UTC) on 26 September 1997. It was preceded by several foreshocks, beginning with a Mw 4.5 event on 3 September. A second and slightly larger shock occurred about nine hours later at 11:40 CEST (09:40 UTC), rated Mw 6.0. The epicentres of first two larger earthquakes were in Annifo. The shaking associated with first two larger shocks was estimated at VIII (Severe) and X (Extreme) on the Mercalli intensity scale, respectively.
There were several thousands of foreshocks and aftershocks from May 1997 to April 1998, more than thirty of which had a magnitude more than 3.5. Eleven people died and approximately 100 were injured, with significant damage to buildings including the partial collapse of the ceiling vault in the Basilica of Saint Francis of Assisi. The earthquakes occurred along faults oriented parallel to the Apennine Mountains and demonstrated how seismic events can influence subsequent earthquakes through alterations in stresses within the upper crust.