Dike Arrest Identification by Reverse Focal Mechanisms: Evidence From Etna Eruptions

Abstract Real‐time prediction of dike behavior during an eruption remains a significant challenge. Determining the timing and location of dike propagation arrest is crucial for hazard evaluation. The inherent complexity of eruptive phenomena makes rapid, unambiguous interpretation through modeling difficult. To overcome this drawback, identifying observables that can rapidly support prediction and decision‐making is crucial. For Etna volcano, we have moved in this direction by focusing on seismological observables, aiming to facilitate quick predictions and informed decisions. We have identified the presence of reverse focal mechanisms during the final stage of dike intrusion as a key observable that accompanies and distinguishes potential propagation arrest. This study examines the four critical case studies of dike arrest occurred in 1989, 2002, 2008, and 2018 during lateral intrusions at Mount Etna. The proposed approach proves to be a valuable tool for assessing dike propagation hazards during the early stages of an eruptive intrusion.