Coseismic folding during ramp failure at the front of the Sulaiman fold-and-thrust belt

The Sulaiman Fold Thrust (SFT) in Central Pakistan formed during the India-Eurasia collision in the late Cenozoic. However, the mechanics of shortening of the brittle crust at time scales of seismic cycles is still poorly understood. Here, we use spaceborne radar interferometry to analyze the deformation associated with the 2015 moment magnitude (Mw) 5.7 Dajal earthquake at the eastern boundary of the SFT. We use kinematic inversions to determine the distribution of slip on the frontal ramp and of flexural slip along active axial surfaces for the forward verging two end-member models: a double fault-bend fold system and a fault-propagation fold. In both models, a decollement branches into a shallow ramp at approximately 7 km depth with coseismic folding in the hanging wall. The Dajal earthquake ruptured the base of the foreland-vergent Boundary Thrust buried under sediment from the Indus River floodplain, representing fault-bending or fault-propagation folding near Sakhi-Sarwar fault-bend 30 km east of its surface exposure.