EGU2020-6836
https://doi.org/10.5194/egusphere-egu2020-6836
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

A study of the generation mechanism of the ocean gravity waves excited by seismic surface waves, based on the comparison of the numerical experiments results and observation data

Kirill A. Sementsov1, Mikhail A. Nosov1,2, Sergey V. Kolesov1,2, Viacheslav A. Karpov1,2, Hiroyuki Matsumoto3, and Yoshiyuki Kaneda4
Kirill A. Sementsov et al.
  • 1Chair of Physics of Sea and Inland Water, Faculty of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow, Russia 119991
  • 2Institute of Marine Geology and Geophysics, Far Eastern Branch of Russian Academy of Sciences, Nauki 1B, Yuzhno Sakhalinsk, Russia 693022
  • 3Japan Agency for Marine-Earth Science and Tec A study of the generation mechanism of the ocean gravity waves excited by seismic surface waves, based on the comparison of the numerical experiments results and observhnology (JAMSTEC), 2 15 Natsushima, Yokos
  • 4Institute of Education, Research and Regional Cooperation for Crisis Management, Kagawa University, 1 1 Saiwai cho, Takamatsu 760 8521, Japan

The DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) is a submarine cabled real-time seafloor observatory network for precise earthquake and tsunami monitoring. Ten DONET observatories were in operation during the 2011 Tohoku-Oki event near the Pacific coast of Honshu Island. Each observatory was equipped with an ocean bottom pressure gauge (PG) and a three-component ocean bottom seismometer (OBS). A comparative analysis of the PG and OBS records revealed that shortly after seismic surface waves traversed the DONET region, free gravity waves were observed within the water layer. The period of these gravity waves was approximately 170 s, the peak-to-peak amplitude was approximately 3.5 cm, the length was on the order of 22 km, and the phase velocity was 134 m/s. We performed numerical simulations of the observed gravity waves using a combined 2D/3D numerical model. The ground motions required for the simulation were reconstructed from records provided by the DONET OBSs and the nearest ground-based GPS stations. The synthetic bottom pressure variations are in good agreement with the DONET PG records. The synthetic displacements of the ocean surface throughout the simulation domain showed that the observed gravity waves were excited directly above the submarine slopes. Theoretical estimates and numerical experiments revealed the generation mechanism of the observed gravity waves. The results showed that (1) horizontal, rather than vertical, bottom movements play a key role in their generation, (2) the amplitude of the excited gravity waves is determined by the amplitude of the dynamic horizontal bottom motions, while the contribution of horizontal static bottom displacements is insignificant, and (3) the amplitude of the excited gravity waves depends on the relative orientation of the slope and the propagation direction of the seismic surface waves.

The study was supported by Russian Foundation for Basic Research (projects 20-35-70038, 19-05-00351, 20-07-01098).

Sementsov, K. A., Nosov, M. A., Kolesov, S. V., Karpov, V. A., Matsumoto, H., & Kaneda, Y. (2019). Free gravity waves in the ocean excited by seismic surface waves: Observations and numerical simulations. Journal of Geophysical Research: Oceans, 124, 8468–8484. https://doi.org/10.1029/2019JC015115

Nosov, M. A., Sementsov, K. A., Kolesov, S. V., Matsumoto, H. & Levin, B. W. (2015). Recording of gravity waves formed in the ocean by surface seismic waves during the earthquake of March 11, 2011, off the coast of Japan. Doklady Earth Sciences, 461 (2), 408-413. https://doi.org/10.1134/S1028334X15040121

How to cite: Sementsov, K. A., Nosov, M. A., Kolesov, S. V., Karpov, V. A., Matsumoto, H., and Kaneda, Y.: A study of the generation mechanism of the ocean gravity waves excited by seismic surface waves, based on the comparison of the numerical experiments results and observation data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6836, https://doi.org/10.5194/egusphere-egu2020-6836, 2020

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