Performance of earthquake early warning systems during the 2016-2017 M (sub w) 5-6.5 central Italy sequence

Earthquake early warning systems (EEWSs) are nowadays contributing to seismic risk mitigation actions, both in terms of losses and societal resilience, by issuing an alert promptly after the earthquake origin and before the ground-shaking impacts the target to be protected. In this work, we analyze the performance of network-based and stand-alone (on-site) early warning systems during the 2016-2017 central Italy sequence, characterized by events with magnitude as large as 6.5. For the largest magnitude event, both systems predict well the ground shaking nearby the event source, with a rate of success in the 85%-90% range, within the potential earthquake damage zone. However, the lead time, that is, the time available for security actions, is significantly larger for the network-based system. For the regional system, it increases to more than 10 s at 40 km from the event epicenter. The stand-alone system performs better in the near-source region, still showing a positive albeit small lead time (<2 s). Far away from the source (>60 km), the performances slightly degrade, mostly owing to the large uncertainty in the attenuation relationships. This study opens up the possibility for making an operational EEWS in Italy, based on the available acceleration networks, provided that the delay due to data telemetry has to be reduced.