Browsing by Author "Satake, K."

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    Far-field tsunami data assimilation for the 2015 Illapel earthquake
    (2019) Wang, Y.; Satake, K.; Cienfuegos Carrasco, Rodrigo Alberto; Quiroz, M.; Navarrete Campos, Paula Cristina
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    History and features of trans-oceanic tsunamis and implications for paleotsunami studies
    (2020) Satake, K.; Heidarzadeh, M.; Quiroz Valeria, Marco Enrique; Cienfuegos Carrasco, Rodrigo Alberto
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    Sea surface network optimization for tsunami forecasting in the near field: application to the 2015 Illapel earthquake
    (OUP, 2019) Navarrete, P.; Cienfuegos Carrasco, Rodrigo Alberto; Satake, K.; Wang, Y.; Urrutia, A.; Benavente, R.; Catalan, P. A.; Crempien de la Carrera, Jorge; Mulia, I.
    We propose a method for defining the optimal locations of a network of tsunameters in view of near real-time tsunami forecasting using sea surface data assimilation in the near and middle fields, just outside of the source region. The method requires first the application of the empirical orthogonal function analysis to identify the potential initial locations, followed by an optimization heuristic that minimizes a cost-benefit function to narrow down the number of stations. We apply the method to a synthetic case of the 2015 M w 8.4 Illapel Chile earthquake and show that it is possible to obtain an accurate tsunami forecast for wave heights at near coastal points, not too close to the source, from assimilating data from three tsunameters during 14 min, but with a minimum average time lag of nearly 5 min between simulated and forecasted waveforms. Additional tests show that the time lag is reduced for tsunami sources that are located just outside of the area covered by the tsunameter network. The latter suggests that sea surface data assimilation from a sparse network of stations could be a strong complement for the fastest tsunami early warning systems based on pre-modelled seismic scenarios.
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    Tsunami Resonance Characterization in Japan due to Trans‐Pacific Sources: Response on the Bay and Continental Shelf
    (2021) Wang, Y.; Zamora, N.; Quiroz, M.; Satake, K.; Cienfuegos, R.
    The tsunami resonance leads to the amplification of wave heights and extends the duration of wave activity. For tsunami warning and coastal planning, it is important to understand resonance behavior. We characterized the tsunami resonance of trans-Pacific events in the bays and continental shelves of Japan, focusing on the Hokkaido and Sanriku regions. We considered five tsunami events with sources in the Peru-Chile subduction zone and the Alaska-Aleutian subduction zone. Spectral analysis was applied to observed and synthetic waveforms at coastal tide gauges and offshore GPS gauges to study the frequency content of tsunami energy, and modal analysis was conducted to investigate the eigen-modes of the natural oscillation affected by regional and local bathymetry. It was found that the signatures of trans-Pacific tsunami sources are lost in the spectra at most coastal gauges, but they partly remain in the spectra at offshore gauges, which are affected less significantly by topography or bathymetry. The predominant periods in the spectra at most coastal gauges match the eigen-periods of natural oscillation calculated by modal analysis. Hence, we confirmed that regional or local bathymetry is the dominant factor in the resonance behaviors of trans-Pacific tsunami events, rather than the source location or geometry. These findings are based on the systematic assessment of trans-Pacific sources and have implications for tsunami warning and coastal planning along the Pacific coast of Japan.