Marco Caciagli

Coseismic ruptures of the 24 August 2016, Mw 6.0 Amatrice earthquake (central Italy)

On 24 August 2016, a Mw 6.0 normal faulting earthquake struck central Italy, causing about 300 fatalities and heavy damage. A geological survey collected the coseismic effects observed at the surface in order to evaluate two competing hypotheses about their nature: surface faulting versus gravitational deformation. We find that the most significant geological effect is a 5.2 km-long alignment of ground ruptures along the Mt. Vettore Fault-System. These ruptures are independent from lithology, topography, morphology and change in slope and exhibit an average dip slip displacement of ~13 cm. Geometry, kinematics and dimensional properties of this zone of deformation strongly lead us to favor the primary surface faulting hypothesis that fits well the predicted estimates from experimental scaling-law relationships. Our study provides relevant hints for surface faulting in extensional domains, contributing to implement the worldwide database of the moderate earthquakes.