We have simulated the tsunami generated from the M 7.1 – 40km SSW of Acari, Peru (15.776°S, 74.744°W, depth=36.3 km, M = 7.1 at 09:18:45.070 UTC according to USGS) on January 14, 2018. The assumed tsunami source is located within the aftershock area (Fig. 1). The fault length and width are 50 km × 25 km. The focal mechanism is strike=314º, dip=39º, slip=92º from the USGS’s W-phase moment tensor solution. The top depth of the fault was assumed to 10 km. The average slip on the fault is 1.0 m. The seismic moment is 5.934 x 1019Nm (Mw = 7.1) assuming the rigidity of 5 x 1010 N/m2.
Figure 1. Tsunami source model, the red lines indicate uplift with the contour interval of 0.1 m. The epicenter is shown by the blue star. 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 the 2017 Mw8.2 Mexico Earthquake, Pure Appl. Geophys. 175, 35-48.
Bruno Adriano (Dr. Eng.) 