Potential and Challenges of FinDer-Based Earthquake Early Warning in Northeastern Italy

Accounting for the finite spatial extent of earthquake rupture is critical for effective regional Earthquake Early Warning (EEW), particularly for large events where point-source assumptions may fail. The Finite fault rupture Detector (FinDer) algorithm addresses this challenge by rapidly inferring the location, extent, and orientation of an ongoing earthquake fault rupture through comparison of the observed spatial distributions of high-frequency ground-motion amplitudes with pre-calculated templates derived from empirical ground motion models. Northeastern Italy, characterized by moderate-to-large seismicity primarily associated with active reverse and strike-slip faulting, represents a suitable test region for finite-fault-based EEW. We evaluate FinDer performance using a combination of real-time detections (M_W < 4.5) and offline playback experiments (5.5 < M_W < 6.7), acknowledging that real-time EEW timeliness is affected by telemetry latency in the current seismic station network. Results show rapid convergence toward stable event locations and magnitudes, while line-source orientation remains weakly constrained, especially for small magnitude events. Sensitivity analyses indicate that increasing station density improves the stability of source-parameter estimates, and that amplification factor-based adjustments for site effects reduce systematic biases in FinDer’s template-matching solutions. Lead times estimated from offline playback tests are also evaluated relative to macroseismic intensity thresholds corresponding to slight damage in unreinforced masonry buildings, with selected scenarios yielding non-negligible lead times. Overall, the results suggest that a properly configured FinDer-based EEW system, supported by real-time telemetry, could provide significant benefits for seismic-risk mitigation in Northeastern Italy. Nevertheless, template simplifications and the neglect of radiation-pattern effects remain major limitations, particularly for reliable strike estimation in smaller events (M_W < 4.5).