Two strong earthquakes just two hours apart rattled central Italy today, and the temblors were felt as far south as Rome.
A 5.5-magnitude quake struck roughly 6 miles (9 kilometers) southeast of the town of Norcia at around 10 a.m. local time. Just 2 hours later, a larger, magnitude-6.1 quake struck about 11 miles (18 km) from the medieval town and just 1.6 miles (2 km) from the smaller town of Visso.
Norcia has seen its share of shaking in recent months. In August, the same region was struck by a magnitude-6.2 quake that left hundreds of people dead as medieval-era stone buildings collapsed, according to CNN. [Photos of This Millennium's Most Destructive Earthquakes]
The region is so earthquake-prone because of the complex geology underlying the ground in the region. Central Italy sits atop the Tyrrhenian basin, a region beneath the Mediterranean Sea where the earth is spreading apart, Julie Dutton, a geophysicist with the U.S. Geological Survey, previously told Live Science.
In northern Italy, the slow-motion crash of the Eurasian and African plates has forged the Alps, but this collision zone is migrating southeast, which stretches the crust that sits beneath the Mediterranean, she said. The ground extension occurs perpendicular to the Alps.
As a result, this region of central Italy is no stranger to the ground shaking. For instance, in 2009, a magnitude-6.3 earthquake struck L'Aquila. Records dating to the 1300s also record horrific quakes that occurred fairly regularly in the towns dotting the Alps. Some were so severe that whole towns were abandoned, the records reveal.
Original article on Live Science.