Remote Sensing, Machine learning, Numerical Simulation, and Disaster Management

Preliminary Tsunami Simulation of the 44km E of Great Swan Island, Honduras Earthquake

We have simulated the tsunami generated from the 44km E of Great Swan Island, Honduras earthquake (17.47°N, 83.52°W, depth=10.0 km, M = 7.6 at 2018-01-10 02:51:31.990 UTC according to USGS) on January 10, 2018 (Fig. 1). The assumed tsunami source is located within the aftershock area (Fig. 1). The fault length and width are 152 km × 20 km. The focal mechanism is strike=254º, dip=65º, slip=2º from the USGS’s W-phase moment tensor solution. The top depth of the fault was assumed to be 1 km. The average slip on the fault is 3.8 m. The seismic moment is 2.765 x 10^{20} Nm (Mw = 7.6) assuming the rigidity of 5 x 10^{10} N/m^{2}

Figure 1. Tsunami source model, the red lines indicate uplift with a contour interval of 0.2 m, while the blue dotted lines indicate subsidence with a contour interval of 0.1 m. The epicenter and aftershock determined by USGS are shown by the blue star and red circles, respectively. The focal mechanism defined by USGS is also shown.

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)

References 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 2017 Mw8.2 Mexico Earthquake, Pure Appl. Geophys. 175, 35-48.