Bernard, E., L. Tang, Y. Wei, and V. Titov (2014): Impact of near-field, deep-ocean tsunami observations on forecasting the 7 December 2012 Japanese tsunami. Pure Appl. Geophys., 171(12), 3483–3491, doi:10.1007/s00024-013-0720-8.
Wei, Y., A.V. Newman, G.P. Gavin, V.V. Titov, and L. Tang (2014): Tsunami forecast by joint inversion of real-time tsunami waveforms and seismic or GPS data: Application to the Tohoku 2011 tsunami.Pure Appl. Geophys., 171(12), 3281–3305, doi:10.1007/s00024-014-0777-z.
Zhou, H., Y. Wei, L. Wright, and V. Titov (2014): Waves and currents in Hawaiian waters induced by the dispersive 2011 Tohoku tsunami. Pure Appl. Geophys., 171(12), 3365–3384, doi:10.1007/s00024-014-0781-3.
In December, Pure and Applied Geophysics (PAGEOPH) published the topical issue, Tsunamis in the Pacific Ocean: 2011-2012, which contains 21 new papers discussing tsunami events that occurred in this two-year span. PMEL scientists contributed three of the papers to this issue.
Bernard et al. report on a small tsunami produced by a Mw 7.3 earthquake offshore of Japan, adjacent to the source region for the 2011 Tohoku event. They present deep-water tsunameter data from the event, recorded on instruments that were deployed just two weeks before the earthquake. Using data from the 2011 Tohoku earthquake, Wei et al. applied several different source models, based on different data sources, to simulate the generation, propagation, and inundation of tsunami waves in the near field. Their results highlight the critical role these deep-ocean tsunami measurements play in the rapid determination of an approximate tsunami source suitable for issuing reliable and accurate forecasts. Zhou et al. examine the effects of frequency dispersion on tsunami waves and currents from the 2011 Tohoku event, with results indicating that dispersion effects generally result in reduced amplitudes of the leading tsunami waves.
Bernard, E., L. Tang, Y. Wei, and V. Titov (2014): Impact of near-field, deep-ocean tsunami observations on forecasting the 7 December 2012 Japanese tsunami. Pure Appl. Geophys., 171(12), 3483–3491, doi:10.1007/s00024-013-0720-8. [Open Access. A Japanese translation of this article is available upon request.]
Following the devastating 11 March 2011 tsunami, two deep-ocean assessment and reporting of tsunamis (DART) stations were deployed in Japanese waters by the Japanese Meteorological Agency. Two weeks after deployment, on 7 December 2012, a Mw 7.3 earthquake off Japan's Pacific coastline generated a tsunami. The tsunami was recorded at the two Japanese DARTs as early as 11 min after the earthquake origin time, which set a record as the fastest tsunami detecting time at a DART station. These data, along with those recorded at other DARTs, were used to derive a tsunami source using the National Oceanic and Atmospheric Administration tsunami forecast system. The results of this analysis show that data provided by the two near field Japanese DARTs can not only improve the forecast speed but also the forecast accuracy at the Japanese tide gauge stations. This study provides important guidelines for early detection and forecasting.
Wei, Y., A.V. Newman, G.P. Gavin, V.V. Titov, and L. Tang (2014): Tsunami forecast by joint inversion of real-time tsunami waveforms and seismic or GPS data: Application to the Tohoku 2011 tsunami.Pure Appl. Geophys., 171(12), 3281–3305, doi:10.1007/s00024-014-0777-z.
Correctly characterizing tsunami source generation is the most critical component of modern tsunami forecasting. Although difficult to quantify directly, a tsunami source can be modeled via different methods using a variety of measurements from deep-ocean tsunameters, seismometers, GPS, and other advanced instruments, some of which are in real or near-real time. Here we assess the performance of different source models for the destructive 11 March 2011 Japan tsunami using model–data comparison for the generation, propagation, and inundation in the near-field of Japan. This comparative study of tsunami source models addresses the advantages and limitations of different real-time measurements with potential use in early tsunami warning in the near- and far- field. The study highlights the critical role of deep-ocean tsunami measurements and rapid validation of the approximate tsunami source for high-quality forecasting. We show that these tsunami measurements are compatible with other real-time geodetic data, and may provide more insightful understanding of tsunami generation from earthquakes, as well as from nonseismic processes, such as submarine landslides.
Zhou, H., Y. Wei, L. Wright, and V. Titov (2014): Waves and currents in Hawaiian waters induced by the dispersive 2011 Tohoku tsunami. Pure Appl. Geophys., 171(12), 3365–3384, doi:10.1007/s00024-014-0781-3.
Ocean waves of short wavelength travel at different speeds. This phenomenon is referred to asfrequency dispersion in fluid dynamics. This study focuses on the effects of frequency dispersion on tsunami-induced coastal water waves and currents, exemplified by the 2011 Tohoku tsunami event. The investigation relies on numerical simulations, starting from a tsunami source constrained through NOAA’s tsunami inundation forecast system. The trans-Pacific propagation and hydrodynamic processes in the Hawaiian Islands region are simulated with one model that takes into account the frequency dispersion and another that neglects the dispersion effects. This study shows that the frequency dispersion effects generally lower the amplitudes of leading waves. Trailing waves of short wavelengths and high amplitudes can develop in coastal waters, and a model neglecting the dispersion effects could underpredict the wave heights and current speeds of these trailing waves.