Spatiotemporal Evolution of Ground-Motion Intensity at the Irpinia Near-Fault Observatory, Southern Italy

ABSTRACT Fault zones are major sources of hazard for many populated regions around the world. Earthquakes still occur unanticipated, and research has started to observe fault properties with increasing spatial temporal resolution, having goal detecting signs stress accumulation strength weakening that may anticipate rupture. The common practice is monitoring source parameters retrieved from measurements; however, model dependence strong uncertainty propagation hamper their usage small microearthquakes. Here, we decipher ground motion (i.e., shaking) variability associated microseismicity detected by dense seismic networks at a near-fault observatory in Irpinia, Southern Italy, obtain an unprecedentedly sharp picture evolution both time space. We discuss link between ground-motion intensity considered microseismicity, showing coherent distribution corner frequency, drop, radiation efficiency. Our analysis reveals presents annual cycle agreement independent geodetic displacement observations two Global Navigation Satellite System stations area. analyses also reveal heterogeneous behavior adjacent segments high risk Italian Concerning properties, highlight segment where 1980 Ms 6.9 Irpinia earthquake nucleated shows changes event-specific signature signals since 2013, suggesting frictional properties. This evidence, combined complementary information on frequency–magnitude distribution, differences response tectonic loading, rupture scenarios future moderate large earthquakes assessment.