Preliminary Tsunami Simulation of the M 6.9 Off-Fukushima, Japan (updated)

We have simulated the tsunami generated from the 44km E of Great Swan Island, Honduras earthquake (37.392°N, 141.403°E, depth=11.4 km, M = 6.9 at 2016-11-21 02:59:49 UTC according to USGS) on November 21, 2016 (Fig. 1). The assumed tsunami source is located within the aftershock area (Fig. 1). The tsunami source is based on the slip distribution proposed by Adriano et al., (2018). The top depth of the fault was assumed to 1.5 km. The maximum slip on the fault model was 4.66 m. The seismic moment is  3.18 x 1019 Nm (Mw = 6.95) assuming the rigidity of 2.7 x 1010 N/m2


Figure 1. Tsunami source model, the red lines indicate uplift with the contour interval of 0.2 m, while the blue dotted lines indicate subsidence with the contour interval of 0.1 m.

As the initial condition for tsunami, static deformation of the seafloor is calculated for a rectangular fault model [Okada, 1985] using the source model. The used bathymetry data is the 30 arc-second grid data from GEBCO for coastal tide gauges. To calculate tsunami propagation, the linear shallow-water, or long-wave, equations were numerically solved by using a finite-difference method [Adriano et al., 2018].


Figure 2. Maximum Height of Simulated Tsunami

by Bruno Adriano and Shunichi Koshimura (IRIDeS, Tohoku University)

Okada, Y. (1985), Surface Deformation Due to Shear and Tensile Faults in a Half-Space, Bull. Seismol. Soc. Am., 75, 1135-1154.

Adriano, B., Fujii, Y., Koshimura, S. et al. (2018), Tsunami Source Inversion Using Tide Gauge and DART Tsunami Waveforms of the 2017 Mw8.2 Mexico Earthquake, Pure Appl. Geophys. 175, 35-48.

Copyright © 2018 Bruno ADRIANO All rights reserved.