New insights into the rheology of a normal fault: the Mw6.1 2009 L’Aquila case study

The study of seismogenic faults is one of the most interesting topics in seismology.  Obtaining a more detailed image of the fault zone structure and of its properties (e.g., fluid content, permeability, lithology, rheology) is fundamental to understand how seismic ruptures originate, propagate and arrest and to study the triggering processes.  The 2009 Mw 6.1 L’Aquila seismic sequence is a perfect case study to reach this goal, thanks to the huge amount of multidisciplinary data available. 

In this study, we reprocess the high-precision large earthquake catalog available for the L’Aquila seismic sequence, focusing on the main (Paganica) seismogenic fault (about 20,000 earthquakes occurring between January-December 2009). We used cross-correlation and double-difference tomography methods to compute high-resolution (2.5 x 2.5 x 2 km grid spacing) Vp and Vp/Vs models along the fault plane. High-resolution Vp and Vp/Vs models give insights into the rheology of the Paganica fault, suggesting new ideas on earthquake generation, propagation and arrest.