Interconnection of multi-scale standing waves across the Pacific Basin from the 2011 Tohoku Tsunami

- Non-hydrostatic modeling of the 2011 Tohoku tsunami across the Pacific basin for 3 days
- Validation of model results with 29 DART records in time and frequency domains
- Interconnected, basin-wide standing waves driving regional oscillations
- Correlation of oscillation modes with rupture configurations as well as shelf and nonlinear wave processes
- Enduring coastal surges from coupling with lightly-damped basin-wide oscillations

Water-level stations across the Pacific Basin recorded persistent oscillations over a wide period range and many maritime facilities sustained long closure due to unabating surges following the 2011 Tohoku tsunami. We utilize a non-hydrostatic model to reconstruct the tsunami from the seismic source and to capture the sub- and super-harmonics from nonlinear wave interactions for elucidation of the basin-wide oscillation processes. A Kalman filter extracts the broad-banded tsunami signals from 29 DART buoys for validation of the model results. Spectral analysis of the computed surface elevation reveals intricate multi-scale oscillation patterns. Networks of standing waves with periods between 5 and 80 min crisscross the Pacific Ocean with amplification along island chains and continental margins. Standing waves between 100- and 410 min period show strong directivity between northeast Asia and South America and at 630 min transform into a circum-Pacific mode. The results show interconnection of the observed oscillations across the Pacific that provides an explanation for the persistent energetic surges nearshore and long-lasting coda in the deep ocean.