A sequence of major earthquakes struck central Italy, killing eleven people and causing notable damage to the Basilica of Saint Francis of Assisi.
Key Facts
- Main shock magnitude
- Mw 6.0
- First major shock magnitude
- Mw 5.7
- Deaths
- 11 people
- Injuries
- ~100 people
- Shocks above Mw 5
- 8
- Mercalli intensity (second shock)
- X (Extreme)
By the Numbers
Location
Cause → Event → Consequence
The earthquakes occurred along normal faults oriented parallel to the Apennine Mountains in central Italy. Seismic activity in the region had been building since at least May 1997, with foreshocks beginning as early as 3 September 1997 and a Mw 4.5 event immediately preceding the main sequence.
On 26 September 1997, two major shocks struck near Annifo in the Umbria and Marche regions: a Mw 5.7 at 02:33 CEST and a larger Mw 6.0 some nine hours later. The sequence ultimately comprised eight earthquakes above Mw 5 and thousands of foreshocks and aftershocks spanning September 1997 to April 1998.
Eleven people died and roughly 100 were injured. Significant structural damage occurred across the affected regions, most notably the partial collapse of the ceiling vault in the Basilica of Saint Francis of Assisi. The sequence also provided scientific evidence that seismic events can alter stress patterns in the upper crust, influencing subsequent earthquakes.
Human Cost
Each dot represents approximately 10,000 deaths. Total estimated: 11 (earthquake)