Slip rate deficit and earthquake potential on shallow megathrusts

Most destructive tsunamis are caused by seismic slip on the shallow part of offshore megathrusts. The likelihood this behaviour is partly determined interseismic rate deficit, which often assumed to be low based frictional studies fault material. Here, we present a new method for inferring deficit from geodetic data that accounts stress shadow cast frictionally locked patches, and show approach greatly improves our resolution. We apply technique Cascadia Japan Trench megathrusts find that, wherever patches present, generally has between 80 100% plate convergence rate, irrespective its properties. This finding rules out areas kinematic coupling at trench considered previous studies. If these can seismically, global tsunami hazard could higher than currently recognized. Our identifies critical locations where seafloor observations yield information about properties faults so as better understand their behaviour. Shallow parts up-dip have high mean been underestimated, according stress-constrained inversion data.