Estimation of Displacement and Extension due to Reverse Drag of Normal Faults: Forward Method

Abstract

In the case of reverse drag of normal faulting, the displacement and horizontal extension are determined based on the established equations for the three mechanisms: rigid body, vertical shear and inclined shear. There are three sub-cases of basal detachment for the rigid body model: horizontal detachment, antithetic detachment and synthetic detachment. For the rigid body model, the established equations indicate that the total displacement on the synthetic base ( D t2 ) is the largest, that on the horizontal base ( D t1 ) is moderate, and that on the antithetic base ( D t3 ) is the smallest. On the other hand, the value of ( D t1 ) is larger than the displacement for the vertical shear ( D t4 ). The value of ( D t1 ) is larger than or less than the displacement for the inclined shear ( D t5 ) depending on the original fault dip δ 0 , bedding angle θ , and the angle of shear direction β . For all original parameters, the value of D t5 is less than the value of D t4 . Also, by comparing three rotation mechanisms, we find that the inclined shear produces largest extension, the rigid body model with horizontal detachment produces the smallest extension, and the vertical shear model produces moderate extension.