Fifty years of seismicity of Mt. Vesuvius

Abstract The seismicity of Mt. Vesuvius over the last 50 years reveals a persistently low-energy regime, yet a detailed analysis uncovers patterns connected to different dynamics in the volcanic structure. This study uses high-resolution seismic data, which has been significantly enriched by the post-2014 expansion of the monitoring network, in order to characterize seismic activity with enhanced accuracy and detail. A clear duality emerges between shallow and deeper seismicity: shallow events, mostly confined within the cone, display b-values close to 1 indicative of brittle failure, potentially driven by gravitational instability; conversely, deeper events below sea level exhibit distinct seismogenic characteristics with higher b-values, possibly linked to magmatic or hydrothermal processes. The second family can be subdivided into two groups. However, the deeper group has an insufficient population size for statistical analysis. The identification of a ”knee” in Gutenberg-Richter distributions around $$Md \sim 2$$ supports the existence of two separate event populations, reinforcing the hypothesis of distinct physical regimes at different depths. Crucially, the study emphasizes how advances in seismic monitoring have drastically lowered the magnitude of completeness, enabling the detection of previously unresolved low-magnitude seismicity. By combining refined observational capabilities with robust statistical analyses, this work provides novel insights into the internal processes of Mt. Vesuvius and underscores the critical role of continuous monitoring in mitigating volcanic risk for the densely populated region.