Investigating the effect of stratigraphic heterogeneity on the stress distribution resulting from the activity of blind thrust faults using numerical modeling


1 Department of Geology, Faculty of Sciences, Golestan University, Gorgan, Iran

2 Department of Geology, Faculty of Sciences, university of Golestan

3 Department of Civil Engineering, Faculty of Engineering, Golestan University, Gorgan, Iran

4 , Department of Geology, Faculty of Sciences and Earthquake Research Center of Shahid Bahonar University of Kerman, Iran


Blind thrust faults are not visible on the ground, but they are able to grow and transfer stress to the surface and surrounding areas during earthquakes. The sequence covering the blind faults, which may be composed of different sedimentary units, can affect the growth of rupture and the distribution of stresses due to the movement of these faults. In this study, the effect of stratigraphic heterogeneity on stress distribution has been evaluated using numerical technique (Finite Element method). The simulation results show that the stress concentration in the salt layer and its overlying sequence is significantly reduced compared to the homogeneous model. While in the underlying layers of salt compared to the homogeneous state, more stress has accumulated in a larger area. Furthermore, comparison of the diagrams of vertical displacement show that despite the similar distribution pattern, the displacement values in the heterogeneous model is larger than the homogeneous one. Therefore, it can be concluded that the presence of ductile layers such as salt in the sedimentary sequence, increases the probability of rupture growth (due to stress concentration) in its underlying layers and reduces or stops the rupture growth towards the overlying layers and the ground surface (due to the sharp reduction of stress in the ductile layer). On the other hand, due to the higher degree of deformation (displacement) in the top layers, they facilitate the formation of new fold and fault structures.


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