Near-field tsunami models with rapid earthquake source inversions from land- and ocean-based observations: The potential for forecast and warning

Computation of tsunami models in the region adjacent to large earthquakes immediately after rupture initiation remains a challenging problem. Limitations of traditional seismological instrumentation in the near field and concern by tsunami modelers regarding the nonuniqueness of source inversions and the use of indirect observations have in the past been hurdles for such efforts. Employing near-field data from the Mw 9.0 2011 Tohoku-oki data, we test source models obtained from newly developed algorithms and multisensor data. We demonstrate the ability of such source models determined from land-based coseismic data from the combination of GPS and strong-motion sensors to forecast near-source tsunamis. We also demonstrate that rapid ingestion of offshore shallow water (100-1000m) wave gauge data substantially improves the earthquake source and tsunami forecast. To assess the success of such tsunami models, we rely on detailed comparisons to 2000+ tsunami survey measurements collected after the event. We argue that deployments of shallow water wave gauges coupled with land-based geophysical sensors can, in the future, provide enough information to issue timely and accurate forecasts of tsunami intensity immediately or shortly after rupture initiation of large earthquakes.