A formulation for reliable estimation of active crustal deformation and its application to central Greece

Abstract

A procedure for the analysis of data, concerning seismic moment release and fault‐plane solutions, for the estimation of active crustal deformation is proposed. The formulation takes advantage of all the available historical and instrumental data for the calculation of the ‘size’ of the deformation in a seismic zone and of all the reliable fault‐plane solutions which are available for a broader seismic belt for the determination of the ‘shape’ of the deformation. A detailed analysis of the errors involved in each parameter, based on a Monte Carlo numerical method, is suggested. The proposed procedure is applied to a region of extensional tectonics in central Greece. The resulting seismic strain rates show that the dominant mode of deformation in the area is extension at a rate of the order of 6 mm yr‐1 and a mean azimuth of N25°W. A vertical contraction rate of about 1 mm yr‐1 has also been calculated. The results from geodetic measurements performed by Billiris et al. (1991) declare that the calculated seismic deformation represents about 60 per cent of the total strain of this area. Copyright © 1992, Wiley Blackwell. All rights reserved