What is the resolving power of interferometric data to constrain slip distribution of earthquakes at depth?

Bruno Hernandez
Institut de Protection et de Sûreté Nucléaire, Fontenay-aux-Roses, France
Laboratoire de Géophysique Interne et Tectonophysique, Université Joseph Fourier, Grenoble, France

Fabrice Cotton
Institut de Protection et de Sûreté Nucléaire, Fontenay-aux-Roses, France

Michel Campillo
Laboratoire de Géophysique Interne et Tectonophysique, Université Joseph Fourier, Grenoble, France

Abstract. Interferometry provides spectacular contour maps of the deformation created by earthquakes. Is it possible to use such rich data set to constrain slip distribution of the earthquake at depth? Does SAR data (one component) provide additional information compared to GPS data (vector)? We applied two inversion techniques (genetic and least square) to SAR and GPS data of the 1992 Landers earthquake data separately to test their uniqueness and their resolution with depth and to compare their resolving power on slip distribution along faults. We also applied these techniques to "synthetic" data. We show that the use of interferometric data provides high resolution slip amplitude models, particularly at shallow depth. In order to solve the problem of the lack of resolution at depth, we finally constrain the slip near the surface with geological observations and inverse the slip distribution at depth with SAR data. These results are then used to constrain the rupture front velocity of the earthquake using strong motion data (see Cotton et al., this meeting).