The 2008 Mt. Etna dike arrest: integration of structural investigation, seismic and energy-balance analysis

Abstract

The 13 May 2008 dike intrusion on the northern flank of Mt. Etna provides a rare case in which surface structural evidence can be directly compared with real-time geophysical observations. In this study, we integrate structural field data, high-precision earthquake relocations, focal mechanism analysis, and energy-balance considerations to reconstruct the propagation and arrest of the dike. The mapped dry fracture field offers robust geometric validation on the depth of the dike tip (200–600 m), in agreement with deformation modeling and seismic analysis. The evolution of focal mechanisms shows a transition from normal/strike-slip faulting to reverse faulting in the final stage, indicating the onset of a localized compressional regime consistent with dike arrest. The cumulative seismic moment closely matches the energy value expected to be released by the modeled dike, suggesting that the available elastic strain energy was largely exhausted. The convergence of structural, seismic, and energy-balance evidence makes the 2008 intrusion a benchmark case for rapid, real-time assessment of dike arrest and volcanic hazard mitigation.