Sulawesi Tsunami on Nov. 16, 2008

 

We have simulated the tsunami generated from the earthquake off Sulawesi, Indonesia (1.290°N, 122.100°E, Mw = 7.3 at 17:02:32 UTC according to USGS) on Nov. 16, 2008.
The assumed tsunami source is shown in Fig. 1 with the aftershocks. The fault size is 60 km × 30 km. Top depth of the fault is 15 km. Average slip on fault is 1 m. The seismic moment is 1.26 x 10**20 Nm (Mw = 7.3) assuming the regidity of 7 x 10**10 N/m**2. The focal mechanism is strike = 93º, dip = 22º and slip angle = 88º from the Global CMT solution.
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 2' grid interval resampled from General Bathymetric Chart of the Oceans (GEBCO) 1' grid data. To calculate tsunami propagation, the linear shallow-water, or long-wave, equations were numerically solved by finite-difference method [Satake, 1995].

 

Fig.1 Tsunami Source Model
The red contours indicate uplift with the contour interval of 0.1 m, while the blue contours indicate subsidence with the contour interval of 0.05 m.
Aftershocks (determined by USGS) are also shown by red circles.

 

Fig.2 Maximum Height of Computed Tsunami and Simulated Tsunami Waveforms

Fig.3 Tsunami Propagation (Click to start GIF animation)
The red color means that the water surface is higher than normal sea level, while the blue means lower.

 

by Yushiro Fujii (IISEE, BRI) and Kenji Satake (GSJ, AIST)

References

Okada, Y. (1985), Surface Deformation Due to Shear and Tensile Faults in a Half-Space, Bull. Seismol. Soc. Am., 75, 1135-1154. Satake, K. (1995), Linear and Nonlinear Computations of the 1992 Nicaragua Earthquake Tsunami, Pure and Appl. Geophys., 144, 455-470.

Last Updated on 2008/11/19