Did the September 2010 (Darfield) earthquake trigger the February 2011 (Christchurch) event?

We have investigated the possible cause-and-effect relationship due to stress transfer between two earthquakes that occurred near Christchurch, New Zealand, in September 2010 and in February 2011. The Mw 7.1 Darfield (Canterbury) event took place along a previously unrecognized fault. The Mw 6.3 Christchurch earthquake, generated by a thrust fault, occurred approximately five months later, 6 km south-east of Christchurch's city center. We have first measured the surface displacement field to retrieve the geometries of the two seismic sources and the slip distribution. In order to assess whether the first earthquake increased the likelihood of occurrence of a second earthquake, we compute the Coulomb Failure Function (CFF). We find that the maximum CFF increase over the second fault plane is reached exactly around the hypocenter of the second earthquake. In this respect, we may conclude that the Darfield earthquake contributed to promote the rupture of the Christchurch fault

Final Fault Slip BSZ JGRB53332

This is the dataset (Final Fault Slip) corresponding to the "Dynamic rupture scenarios in the Brawley seismic zone, Salton Trough, southern California" paper published in the Journal of Geophysical Research, Solid Earth, 2019, DOI: 10.1029/2018JB016795. This dataset includes the final fault slip from dynamic rupture experiments described in the paper above.Please read the paper for further detail

Finite element models of coseismic deformation due to the 2009 L'Aquila (Italy) and 2008 Wenchuan(China) earthquakes

The topic of my Ph.D. thesis is the finite element modeling of coseismic deformation imaged by DInSAR and GPS data. I developed a method to calculate synthetic Green functions with finite element models (FEMs) and then use linear inversion methods to determine the slip distribution on the fault plane. The method is applied to the 2009 L’Aquila Earthquake (Italy) and to the 2008 Wenchuan earthquake (China). I focus on the influence of rheological features of the earth's crust by implementing seismic tomographic data and the influence of topography by implementing Digital Elevation Models (DEM) layers on the FEMs. Results for the L’Aquila earthquake highlight the non-negligible influence of the medium structure: homogeneous and heterogeneous models show discrepancies up to 20% in the fault slip distribution values. Furthermore, in the heterogeneous models a new area of slip appears above the hypocenter. Regarding the 2008 Wenchuan earthquake, the very steep topographic relief of Longmen Shan Range is implemented in my FE model. A large number of DEM layers corresponding to East China is used to achieve the complete coverage of the FE model. My objective was to explore the influence of the topography on the retrieved coseismic slip distribution. The inversion results reveals significant differences between the flat and topographic model. Thus, the flat models frequently adopted are inappropriate to represent the earth surface topographic features and especially in the case of the 2008 Wenchuan earthquake

Asymmetric Topography Causes Normal Stress Perturbations at the Rupture Front: The Case of the Cajon Pass

We use 3D dynamic rupture simulations to discover a previously un-described effect of asymmetric topography on the earthquake process. With the Cajon Pass along the San Andreas Fault as an example, we find that asymmetric topography generates an alternating normal stress perturbation around the rupture front, near the free surface. When topography lies to the right of the propagating right-lateral front, the normal stress perturbation is clamping ahead of the rupture front and unclamping behind. When topography alternates to the left, the perturbation reverses sign. The process is analogous to the normal stress variations on dip-slip faults. While this effect does not strongly affect rupture propagation and slip in our current parametrization, it requires explanation and exploration. An understanding of the normal stress perturbation due to asymmetric topography will help prevent its misattribution to other sources and lead to a better understanding of the interplay of multiple processes during earthquakes

FEM inversion of DInSAR data of the 2009 L’Aquila Earthquake (Italy)

Slip distribution on fault planes is usually retrieved by geodetic data assuming the local crust as an elastic, homogeneous and isotropic half-space. Realistic complexities such as non-homogeneous elastic structure and topographic relief can be handled only by numerical methods. However, such elaborated models are computationally expensive and are usually implemented for forward modelling rather than for inversion purposes. On the other hand, spatially dense geodetic data (e.g. DInSAR displacement maps) often reveal complex patterns of coseismic deformation, pointing out the oversimplification of the analytical models. We develop a procedure to perform inversion of geodetic data based on Finite Element (FE) method, accounting for a more realistic description of the Earth crust, e.g. medium heterogeneity, anisotropy, topographic relief. FE computed Green Functions are implemented in an inversion framework to constrain the fault slip distribution in complex media. The method is applied to the 2009 L’Aquila earthquake. Three DInSAR maps of coseismic displacement from ENVISAT and COSMO-Skymed satellites are inverted simultaneously. The FE model includes the heterogeneities of the local crust. Results from inversions highlight the non-negligible influence of the medium structure: homogeneous and heterogeneous models show discrepancies in the fault slip distribution values up to 20%.UnpublishedSan Francisco, USA3.1. Fisica dei terremotiope

FEM inversion of DInSAR data of the 2009 L’Aquila Earthquake (Italy)

Slip distribution on fault planes is usually retrieved by geodetic data assuming the local crust as an elastic, homogeneous and isotropic half-space. However, realistic complexities such as non-homogeneous elastic structure and topographic relief can be handled only by numerical methods. Such elaborated models are computationally expensive and are usually implemented for forward modelling rather than for inversion purposes. On the other hand, spatially dense geodetic data (e.g. DInSAR displacement maps) often reveal complex patterns of coseismic deformation, pointing out the oversimplification of the analytical models. We develop a procedure to perform inversion of geodetic data based on Finite Element (FE) method, accounting for a more realistic description of the Earth crust, e.g. medium heterogeneity, anisotropy, topographic relief. FE computed Green functions are implemented in an inversion framework to constrain the fault slip distribution in complex media. The method is applied to the 2009 L’Aquila earthquake (Mw 6.3). The fault geometry is constrained by three DInSAR maps of coseismic displacement from ENVISAT and COSMO-Skymed satellites. In addition to these re-computed images, we use near-field GPS data. The fault dip is fixed at 50°, in accordance to recently relocated aftershocks of the L’Aquila earthquake. We build a FE model including the fault geometry previously determined and the heterogeneities of the local crust. A linear inversion is performed to constrain the slip distribution in the heterogeneous medium. Results from inversions highlight the non-negligible influence of the medium structure: homogeneous and heterogeneous models show discrepancies in the fault slip distribution values up to 20%.PublishedWien3.1. Fisica dei terremotiope

FEM inversion of DInSAR data of the 2009 L’Aquila Earthquake (Italy)

Slip distribution on fault planes is usually retrieved by geodetic data assuming the local crust as an elastic, homogeneous and isotropic half-space. However, realistic complexities such as non-homogeneous elastic structure and topographic relief can be handled only by numerical methods. Such elaborated models are computationally expensive and are usually implemented for forward modelling rather than for inversion purposes. On the other hand, spatially dense geodetic data (e.g. DInSAR displacement maps) often reveal complex patterns of coseismic deformation, pointing out the oversimplification of the analytical models. We develop a procedure to perform inversion of geodetic data based on Finite Element (FE) method, accounting for a more realistic description of the Earth crust, e.g. medium heterogeneity, anisotropy, topographic relief. FE computed Green functions are implemented in an inversion framework to constrain the fault slip distribution in complex media. The method is applied to the 2009 L’Aquila earthquake (Mw 6.3). The fault geometry is constrained by three DInSAR maps of coseismic displacement from ENVISAT and COSMO-Skymed satellites. In addition to these re-computed images, we use near-field GPS data. The fault dip is fixed at 50°, in accordance to recently relocated aftershocks of the L’Aquila earthquake. We build a FE model including the fault geometry previously determined and the heterogeneities of the local crust. A linear inversion is performed to constrain the slip distribution in the heterogeneous medium. Results from inversions highlight the non-negligible influence of the medium structure: homogeneous and heterogeneous models show discrepancies in the fault slip distribution values up to 20%