We have simulated the tsunami generated from the M 7.5 – 45km NE of Kokopo, Paapua New Guinea (4.081°S 152.569°E, depth=10.0 km, M = 7.5 at 2019-05-14 12:58:26 (UTC) according to USGS. The assumed tsunami sources cover the aftershock area for 2 hours after the mainshock (Fig. 1). The fault size and average slip are 140 km × 15 km and 3.5 m. The focal mechanism is strike=317º, dip=49º, and slip=-26º from the USGS’s W-phase moment tensor solution. The top depth of the fault was assumed to 5 km. The seismic moment is 2.16 x 1020Nm (Mw = 7.5) assuming the rigidity of 5 x 1010N/m2.
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 12 arc-second grid data from GEBCO. 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].
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by Bruno Adriano (RIKEN AIP) and Shunichi Koshimura (IRIDeS, Tohoku University)
Okada, Y. (1985), Surface Deformation Due to Shear and Tensile Faults in a Half-Space, Bulletin of the Seismological Society of America, 75(4), 1135-1154. (link)
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 and Applied Geophysics, 175, 35-48. doi: 10.1007/s00024-017-1760-2