Coseismic ground deformation of the 6 April 2009 L’Aquila earthquake (central Italy, Mw6.3)

Abstract

We provide field data of coseismic ground deformation related to the 6 April Mw 6.3 L’Aquila normal faulting earthquake. Three narrow fracture zones were mapped: Paganica‐Colle Enzano (P‐E), Mt. Castellano‐Mt. Stabiata (C‐S) and San Gregorio (SG). These zones define 13 km of surface ruptures that strike at 130–140°. We mapped four main types of ground deformation (free faces on bedrock fault scarps, faulting along synthetic splays and fissures with or without slip) that are probably due to the near‐surface lithology of the fault walls and the amount of slip that approached the surface coseismically. The P‐E and C‐S zones are characterized by downthrow to the SW (up to 10 cm) and opening (up to 12 cm), while the SG zone is characterized only by opening. Afterslip throw rates of 0.5–0.6 mm/day were measured along the Paganica fault, where paleoseismic evidence reveals recurring paleo‐earthquakes and post‐24.8 kyr slip‐rate ≥ 0.24 mm/yr.