Coseismic Ground Deformation Reproduced through Numerical Modeling: A Parameter Sensitivity Analysis

Panara Panara,Perotti Perotti,Seno Seno,Cooke Cooke,Toscani Toscani

doi:10.3390/geosciences9090370

Abstract

Coseismic ground displacements detected through remote sensing surveys are often used to invert the coseismic slip distribution on geologically reliable fault planes. We analyze a well-known case study (2009 L’Aquila earthquake) to investigate how three-dimensional (3D) slip configuration affects coseismic ground surface deformation. Different coseismic slip surface configurations reconstructed using aftershocks distribution and coseismic cracks, were tested using 3D boundary element method numerical models. The models include two with slip patches that reach the surface and three models of blind normal-slip surfaces with different configurations of slip along shallowly-dipping secondary faults. We test the sensitivity of surface deformation to variations in stress drop and rock stiffness. We compare numerical models’ results with line of sight (LOS) surface deformation detected from differential SAR (Synthetic Aperture Radar) interferometry (DInSAR). The variations in fault configuration, rock stiffness and stress drop associated with the earthquake considerably impact the pattern of surface subsidence. In particular, the models with a coseismic slip patch that does not reach the surface have a better match to the line of sight coseismic surface deformation, as well as better match to the aftershock pattern, than models with rupture that reaches the surface. The coseismic slip along shallowly dipping secondary faults seems to provide a minor contribution toward surface deformation.

Highlights

Understanding the relationships between subsurface slip and coseismic ground deformation provides a foundation for many seismotectonic and seismic hazard assessment studies
Differential SAR (Synthetic Aperture Radar) interferometry (DInSAR) analysis can measure coseismic surface deformation (e.g., [6]) and serve as input data for numerical models that invert for fault geometry and/or fault slip distribution (e.g., [2,3,5,7])
If fault geometry is well constrained, the inversions can produce reliable slip distributions that are consistent with seismic data [2,7]; for this reason, we used geologic and geophysical data in order to constrain a reliable fault configuration

Summary

Introduction

Understanding the relationships between subsurface slip and coseismic ground deformation provides a foundation for many seismotectonic and seismic hazard assessment studies. Starting from the work of Massonnet in 1993 [1], remote sensing techniques have provided new important tools for the detection, observation and measurement of surface coseismic deformation (e.g., [2,3,4,5]). Differential SAR (Synthetic Aperture Radar) interferometry (DInSAR) analysis can measure coseismic surface deformation (e.g., [6]) and serve as input data for numerical models that invert for fault geometry and/or fault slip distribution (e.g., [2,3,5,7]). Despite the large amount of data collected

Methods

Discussion

Conclusion