Assessing Earthquake Early Warning Feasibility at the NITRO Near-Fault Observatory Using Numerical and Offline Simulations

Abstract The effectiveness of earthquake early warning systems (EEWS) depends on multiple factors, both geological and related to the seismic monitoring infrastructure, making feasibility assessments essential. This study evaluates the feasibility of EEWS at the Northeastern Italy Thrust Faults Observatory (NITRO). The assessment is based on extensive numerical simulations using the network-based algorithm PRobabilistic and Evolutionary early warning SysTem, incorporating realistic station-specific data transmission latencies measured over six months at the accelerometric stations within the NITRO virtual network, and complemented by offline replays of the 2024 Mw 4.1 Preone, Italy, earthquake. System performance is quantified in terms of alert timeliness, lead time, and blind zone extent under multiple configuration scenarios. Results indicate that, under the current network configuration, the expected blind zone radius for local events typically exceeds 18–25 km, encompassing a substantial fraction of locations likely to experience damaging ground motion. Scenario-based simulations constrained by historical macroseismic observations suggest that approximately half of the damaged sites would fall within the blind zone, although only a limited fraction would receive alerts with actionable lead times. The definition of actionable lead time depends on the type of end user, ranging from a few seconds for simple personal protective actions to several tens of seconds for complex industrial shutdowns. Offline replays confirm the simulated alert delays and the temporal convergence of source parameter estimates. Overall, although a network-based EEWS implementation at NITRO is technically feasible, its effectiveness in providing actionable early warnings is currently limited. Nevertheless, as suggested by recent social studies, EEWS may still offer valuable rapid post-event information to the end users, including civil protection authorities and the general public, supporting situational awareness and emergency response when integrated within existing seismic monitoring workflows.