Half‐graben rupture geometry of the 30 October 2016 M W 6.6 Mt. Vettore‐Mt. Bove earthquake, central Italy

Abstract

Existing models for the rupture geometry and slip distribution associated with the 30 October Mw 6.6 Mt. Vettore‐Mt. Bove earthquake in central Italy show significant dissimilarities. Indeed, due to the quite complicated observed deformation pattern, the activation of a complex multi‐fault structure during a single seismic event was invoked. In this study, we explore different rupture scenarios and we develop a robust model of the rupture process of the 30 October earthquake, designed from new field observations, aftershocks distribution and static coseismic offsets including new near‐field survey‐mode GPS measurements, regional GPS observations, InSAR interferograms and static displacements derived from strong‐motion stations. Our preferred best‐fit model involves the simultaneously rupture of the master Mt. Vettore‐Mt. Bove normal fault and of at least two secondary antithetic faults (as they significantly contributed to the total deformation field), which overall describe a “simple conceptual” half‐graben normal fault system, and whose arrangement fits the geological, seismological and the coseismic evidence of surface faulting. Notably, our model fits the geometry of seismogenic structures defined prior to the 2016‐2017 seismic sequence by field Quaternary geological observations. In addition, no significant coseismic slip on faults alternative to the master and antithetic faults is necessary to explain the observed surface displacements during the 30 October Mt. Vettore‐Mt. Bove earthquake.