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How the Parameters of a Seismic Surface Wave Governs the Properties of the FGSS Waves in the Ocean

Session: Advances in the Science and Observation of Tsunamis

Type: Oral

Date: 4/22/2021

Presentation Time: 10:00 AM Pacific

Description: 

The key factor that determines the generation of gravity waves in the ocean by submarine earthquakes is the displacement of water by the coseismic bottom displacement (Murty, 1977). However, seismic surface waves are also capable of exciting gravity waves in the water layer (Gutenberg, 1939; Levin &Nosov, 2016; Sementsov et al., 2019). Because Free Gravity waves excited by Seismic Surface waves have not been relatively well studied, there is still no conventionally agreed‐upon name for them. In the (Sementsov et al., 2019) we proposed the abbreviation FGSS waves for them. In the (Sementsov et al., 2019) we studied the FGSS waves, recorded by the DONET bottom observatories during the 2011 Tohoku event. 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 mechanisms of the FGSS waves generation require further study and refinement using numerical experiments. Experiments are carried out using a combined 3D / 2D model of the evolution of tsunami waves (Sementsov et al., 2019). The results of these new experiments will be discussed.

This work was supported by the Russian Foundation for Basic Research (Projects 20-35-70038, 19‐05‐00351, 20-07-01098).

References.

1. Mutry, T. S. (1977). Seismic sea waves—Tsunamis. Ottawa: Fisheries and Marine Service.

2. Gutenberg, B. (1939). Tsunamis and Earthquakes, Bulletin of the Seismological Society of America, 29 (1), 517-526.

3. Levin, B. W., Nosov, M. A. (2016). Physics of Tsunamis, Second Edition. — Springer International Publishing AG Switzerland. — 388 p.

4. Sementsov, K. A. et al. (2019). Journal of Geophysical Research: Oceans, 124(11), 8468-8484.

Presenting Author: Kirill A. Sementsov

Student Presenter: No

Authors