Tectonic stress and seismogenic faulting in the area of the 1908 Messina earthquake, south Italy

Abstract

Stress inversion of the twenty best-quality earthquake fault-plane solutions available in the area of the 1908 Messina earthquake showed a nearly uniform extensional regime with σmin constrained between N284°E and N312°E, coinciding with the direction of extension derived from geostructural data. The misfits of earthquake nodal planes and related slip vectors to the stress tensor allowed us to identify the fault planes of thirteen of the earthquakes used for inversion. In particular, the fault plane of 1908 earthquake was found in the north-trending east-dipping nodal plane of the focal mechanism. These findings and strain tensor estimates performed with the same dataset lead us to propose that in spite of stress uniformity detected over the study area the seismic strain orientations change significantly in the crustal volume under investigation due to different fault orientations in the different sectors. However, when comparing strong earthquakes with background seismicity in a given sector the strain orientations are found to be similar.