Near‐field tsunami inundation forecast using the parallel TUNAMI‐N2 model: Application to the 2011 Tohoku‐Oki earthquake combined with source inversions

To contribute to tsunami early warning systems, we investigated the currently achievable speed of tsunami inundation simulations on a parallel computer as well as the benefits of high‐resolution and faster than real‐time inundation predictions. We found that a 5 m resolution inundation simulation can be 75 times faster than real time, requiring only 1.5 min to overview the inundation situation in Sendai City for the 2011 Tohoku tsunami. We developed a novel parallel tsunami model based on the well‐known TUNAMI‐N2 model and achieved 9.17 tera Floating‐point Operations Per Second (FLOPS) on 9469 CPU cores. The present model can accurately hindcast the observed inundated regions of the 2011 Tohoku tsunami using tsunami source estimations of the tFISH and tFISH/RAPiD algorithms, which can be instantly derived from real‐time observation data. The present high‐resolution predictions can provide clear images of imminent hazards/disasters and can provide guidance for appropriate evacuation actions.