Intermittent Slip Along the Alto Tiberina Low-Angle Normal Fault in Central Italy

The Alto Tiberina normal fault (ATF) in central Italy is a 50-km-long crustal structure that dips at a low angle (15–20°). Events on the fault plane are about 10 times less frequent than those located in its shallower syn- and antithetic hanging-wall splays. To enhance ATF catalog and achieve a better understanding of the degree of coupling in the fault system, we apply a template matching technique in the 2010–2014 time window. We augment by a factor 5 the detections and decrease the completeness magnitude to negative values. Contrary to what previously observed on ATF, we highlight intermittent seismic activity and long-lasting clusters interacting with sequences on the shallower splays. One of these episodes of prolonged seismic activity, detected at the end of 2013 on a 30-km-long ATF segment, suggest the ATF active role during an aseismic transient unraveled by geodetic data.