A simple and accurate method is shown for a static two-dimensional model of a long strike-slip fault in a crust with horizontally varying rigidity. The rigidity variation is approximated by a series of vertical laminated layers. The layer model has an exact solution represented by zero-frequency Thompson-Haskell layer matrices. The slip regime is modeled by a planar displacement discontinuity (i.e., screw dislocations) within one layer.

The method was used to calculate the surface displacement and strain fields for a number of slip regimes and crustal rigidity profiles. In general, it was found that large modifications and/or excursions to the conventionally expected deformation fields resulted using physically reasonable crustal rigidity models. For example, very large local amplification spikes in the strain field were found in crustal low-rigidity zones. The results further showed that not adequately considering crustal strength variations can be a cause of misinterpreting field data. A possible source of “noise” in field observations was also linked to crustal nonuniformity. The demonstrated sensitivity of static data to both large scale and local rigidity variations points up the potential use of dense field observation nets for delineating heterogeneous regions in the crust.

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