Coseismic slip distribution of 2009 L'Aquila earthquake derived from InSAR and GPS data

To better understand the mechanism of the Mw6.3 L'Aquila (Central Italy) earthquake occurred in 2009, global positioning system (GPS) and interferometric synthetic aperture radar (InSAR) data were used to derive the coseismic slip distribution of the earthquake fault. Firstly, based on the homogeneous elastic half-space model, the fault geometric parameters were solved by the genetic algorithm. The best fitting model shows that the fault is a 13.7 kmx14.1 km rectangular fault, in 139.3 degrees strike direction and 50.2 degrees southwest-dipping. Secondly, fixing the optimal fault geometric parameters, the fault plane was extended and discretized into 16x16 patches, each with a size of 1 kmx1 km, and the non-uniform slip distribution of the fault was inverted by the steepest descent method with an appropriate smoothing ratio based on the layered crustal structure model. The preferred solution shows that the fault is mainly a normal fault with slight right-lateral strike slip, the maximum slip of 1.01 m is located in the depth of 8.28 km, the average rake is -100.9 degrees, and the total geodetic moment is about 3.34x1018 N.m (Mw 6.28). The results are much closer than previous studies in comparison with the seismological estimation. These demonstrate that the coseismic fault slip distribution of the L'Aquila earthquake inverted by the crustal model considering layered characters is reliable.