Electronic Supplement to
Visualization of 3-D Wave Propagation from the 2000 Tottori-ken Seibu, Japan earthquake: Observation and Numerical Simulation

by T. Furumura, B.L.N. Kennett and K. Koketsu


MPEG Movies of Observed and Simulated Wavefields

The dense networks of strong ground motion instruments in Japan (K-NET and KiK-net) make it possible to directly visualize regional wave propagation during large earthquakes. For the 2000 Tottori-ken Seibu earthquake (Mw 6.6) in western Japan, snapshots of ground motion, derived directly from interpolation of a large number of array observations, demonstrate clearly the nature of the source radiation pattern and the character of the seismic  wavefield  propagating to regional distances [Movie 1].  In western Japan the wavefield from the earthquake is dominated,  in most parts, by high frequency (0.2-5 Hz) Lg waves on three-component acceleration records and by longer-period  (T =10 s) fundamental-mode Love waves on tangential displacement records. Strong lateral variations in the crust  and upper mantle, such as the low-velocity superficial layer and the high-velocity Philippine-Sea plate with its shallow subduction into the mantle, have significant effects on the regional wavefield.

Further insight into the nature of the seismic wavefield is gained by comparing the observed wavefield with results from a 3-D numerical simulation [Movie 2]. Sedimentary basins are included in the model by using an embedded submesh. A realistic model of the source process for the 2000 Tottori-ken Seibu earthquake is also included in the multigrid, parallel computation by using a hybrid PSM/FDM method. There is good agreement in the dominant features of the regional wavefield which propagates through the complex structure of western Japan [Movie 3] [Figures 1, 2] and the modeling procedure is suitable for estimating the main pattern of ground motion for future earthquake scenarios. For example, the amplification effects in the highly populated sedimentary basins can be observed. The differences between the observations and the computer simulations, however, indicate the need for further refinement of the both source and structural models. 


Movie 1 (5.7MB MPEG file) shows a 3-D view of the absolute horizontal ground motion in western Japan during
the Tottori-ken Seibu earthquake. -It was produced by interpolating velocity waveforms from
521 K-NET and KiK-net strong ground motion stations.

Movie 2 (4.5MB MPEG file) shows the corresponding numerical simulation.

Movie 3 (5.0MB MPEG file) is a combined movie comparing the observed and simulated wavefields.


Snapshots are shown of the observed (left) and simulated (right) ground velocities from the 2000 Tottori-ken Seibu earthquake, at 20s (Fig. 1) and 60s (Fig. 2) after the source initiation.

19 Jul.  2002, Takashi Furumura,  Earthq. Res. Inst., Univ. Tokyo (furumura@eri.u-tokyo.ac.jp)
  3 Sep. 2002, Rev.
27 Nov. 2002. Rev. 2
25 Dec. 2002. Rev. 3, Thanks to Ralph A. Stephan for correcting manuscript.

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