Uncertainty analysis of the 2009 L'Aquila rupture model using one- and three-dimensional crustal structure

Abstract:

Finite-fault rupture models for the 2009 L'Aquila earthquake reveal considerable variability among the published solutions of kinematic source parameters. One potential source of this variability arises from the non-unique choice of crustal structure. This earthquake occurred in an area of complex geology, including a small sedimentary basin and pronounced topography. Therefore, the use of a one-dimensional crustal structure may be insufficient to accurately infer the earthquake rupture process.

In this study, we examine the effects of crustal structure variability on the inversion for the rupture process of the 2009 L'Aquila earthquake. We particularly assess the rupture model uncertainty related to one- and three-dimensional Earth models that are used to compute Green’s functions. In doing so, we evaluate the role of using more realistic crustal structure in resolving the rupture model parameters.

We apply Bayesian inference to quantitatively assess the characteristics of the space-time rupture evolution (peak slip-rate, rupture time, and rise time) in terms of posterior density functions. We find that the use of realistic 3D crustal structure, including topography and crustal heterogeneity improves the earthquake source imaging. We also investigate the sensitivity of rupture parameters with respect to the variations in crustal structure.