Two shallow earthquakes hit central Italy

Two shallow earthquakes shook central Italy near Visso on Wednesday October 26, both considered to be aftershocks of the destructive magnitude (M) 6.2 earthquake that occurred near Terami on August 24.

Damage to building and infrastructure has been reported, although less than would be expected from shocks of these magnitudes due to the widespread destruction from the August earthquake, according to catastrophe modelling firm AIR Worldwide.

The first magnitude 5.5 earthquake struck at 7:10pm local time south-south west of Visso, and the second – a shallow and more intense magnitude 6.1 earthquake – hit just north of Visso two hours later.

A shallow magnitude 5.5 earthquake hit central Italy on 7:10.

“Like the August 24 temblor, the M5.5 and M6.1 earthquakes ruptured as crustal normal faulting events on a northwest-southeast striking oriented fault in the central Apennines,” said Claire Pontbriand, senior scientist at AIR Worldwide.

“Yesterday’s events were deeper aftershocks of the August earthquake, with focal depths of 10.0 kilometres (6.2 miles), compared to the 4.4 kilometres (2.7 miles) focal depth of the deadly August rupture. The largest instrumentally recorded rupture in the region was a devastating 1915 M6.7 earthquake, which resulted in approximately 32,000 deaths.

“Numerous aftershocks have been felt since the initial quakes, including an M4.9 quake, which occurred about two hours after the M6.1 quake. No injuries or deaths have been reported—many people in the region went outside after the initial shock—although darkness and rain hampered early response activities.”

“The two aftershocks struck a region of small towns, many replete with ancient stone buildings, which are highly vulnerable to earthquake shaking. Reportedly, Umbria and Marche were most severely impacted.”

A number of structure damaged by the August earthquake have suffered additional damage, according to AIR.

A bell tower in Camerino damaged by the August 24 earthquake collapsed, destroying an adjacent building.

“Damage was reported near the epicentre, in Visso, as well as in Castelsantangelo sul Nero, where a number of houses were damaged, and in Norcia, where the main square and a church were damaged. In Campi, a church dating to the 15th century, San Salvatore, was damaged by the initial aftershock and then destroyed by the second.”