Modelling of stress patterns along the western part of the north anatolian fault zone

Abstract

The stress field before and after strong ( M ≥ 6) earthquakes in the western part of the North Anatolian Fault Zone is modelled. Assuming an initially homogeneous state of stress, the elastic co-seismic stress-drops, the inelastic post-seismic stress variations and the increase of stress due to plate motion are taken into account, using the theory of dislocations. The model consists of an elastic layer (upper crust) above a half-space which is described by elastic properties and alternatively by a standard linear solid. The results of the latter inelastic model differ only slightly from that of the purely elastic one. One of the main results is that most of the earthquakes fall into regions for which the model calculations predict high stress levels prior to the events. At present, the highest stress values are obtained for an area around 34° E to 35° E. They are higher than the average pre-seismic stress value for the series of eight earthquakes investigated in this study. All results are critically dependent on the assumption of the initial stress field being homogeneous along the western part of the North Anatolian Fault Zone.