Active strike-slip faults and an outer frontal thrust in the Himalayan foreland basin

Significance The Himalayan mountain belt results from continuing convergence between the Indian Plate and Asia. Damaging earthquakes occur on major thrust faults north of the Main Frontal Thrust (MFT). To the south, the Ganga foreland basin is typically described as undeformed. We show that active thrust and strike-slip faults, with accumulated slip up to ∼100 m, pass under the trace of the MFT into the foreland basin in eastern Nepal, leading to propagation of deformation at least ∼37 km into the foreland basin beneath the densely populated Ganga plain. The development of these faults at the active thrust front helps to explain structures preserved in higher thrust sheets of the Himalaya, and in ancient mountain belts elsewhere.