The resolving power of coseismic surface displacement data for fault slip distribution at depth.

The spatial slip distribution of the August 17, 1999, Izmit (Turkey) earthquake has previously been determined from both geodetic and seismological data. Though the models derived agree on a broad scale, they are significantly different in detail. These differences could be due to the inversion techniques applied and/or additional constraints implemented and/or be due to poor resolution. It is also conceivable that the relative agreement at larger scales results in part from a resolution artifact common to all models. To investigate this we perform a resolution analysis of fault slip models based on the inversion of surface displacement data. Assuming the theory of elastic dislocations in a half-space and adopting a parameterization for which model predictions are capable of fitting the spatial variations of the data, the inverse problem proves to be intrinsically ill-conditioned.