Optimal fault resolution in geodetic inversion of coseismic data

With the continued growth in availability of differential interferometry from synthetic aperture radar and GPS data, space based geodesy has been widely applied to image the coseismic displacement field and to retrieve the static dislocation over the fault plane for almost all the significant earthquakes of the past two decades. This is performed by linear data inversion over a set of subfaults, generally characterized by a constant and predefined or manually adjusted dimensions. In this paper, we propose a new algorithm to automatically retrieve an optimized fault subdivision in the linear inversion of coseismic geodetic data. The code iteratively keeps the parameter resolution close to a predefined high value. We first discuss the rationale supporting our algorithm and, after a detailed description of its implementation, we analyse the advantages of its introduction in the data inversion. The algorithm was tested against an exhaustive range of synthetic and real data sets and fault mechanisms. Among them, we present the results for the M-w 6.2, 2009 L'Aquila (Central Italy) earthquake and compare the new and previously published slip distributions showing the disappearance of misleading slip pattern and the increased resolution for shallower zones.