Deep reverse faulting beneath the Kuril trench

Abstract:

The March 25, 2020, Mw 7.5 Kuril earthquake occurred within a few kilometers of the trench, at a reported depth of 52 kilometres (GCMT). The reverse mechanism and depth suggest that the earthquake is associated with plate bending beneath the neutral plane, yet classical models of the oceanic lithosphere strength do not anticipate brittle failure at these depths. We invert broadband P and S full waveforms including their depth phases using a simulated annealing procedure to more accurately constrain the moment tensor and the hypocentral depth. We investigate the implications for the plate/slab dynamics including the location of brittle ductile transition.