The quakes occurred in a seismic gap which is located between the areas hit by the 2016 August earthquake and the one in Umbria and Marche of 1997.
As the process of faulting along the chain of the Apennine Mountains is a relatively recent one in geological terms, starting 500,000 years ago, the faults are more irregular, so more shaking occurs due to foreshocks according to seismologist Ross Stein from Stanford University.