Kinematic earthquake source inversion and tsunami runup prediction with regional geophysical data

Rapid near‐source earthquake source modeling relying only on strong motion data is limited by instrumental offsets and magnitude saturation, adversely affecting subsequent tsunami prediction. Seismogeodetic displacement and velocity waveforms estimated from an optimal combination of high‐rate GPS and strong motion data overcome these limitations. Supplementing land‐based data with offshore wave measurements by seafloor pressure sensors and GPS‐equipped buoys can further improve the image of the earthquake source and prediction of tsunami extent, inundation, and runup. We present a kinematic source model obtained from a retrospective real‐time analysis of a heterogeneous data set for the 2011 Mw9.0 Tohoku‐Oki, Japan, earthquake. Our model is consistent with conceptual models of subduction zones, exhibiting depth dependent behavior that is quantified through frequency domain analysis of slip rate functions. The stress drop distribution is found to be significantly more correlated with aftershock locations and mechanism types when off‐shore data are included. The kinematic model parameters are then used as initial conditions in a fully nonlinear tsunami propagation analysis. Notably, we include the horizontal advection of steeply sloping bathymetric features. Comparison with post‐event on‐land survey measurements demonstrates that the tsunami's inundation and runup are predicted with considerable accuracy, only limited in scale by the resolution of available topography and bathymetry. We conclude that it is possible to produce credible and rapid, kinematic source models and tsunami predictions within minutes of earthquake onset time for near‐source coastal regions most susceptible to loss of life and damage to critical infrastructure, regardless of earthquake magnitude.