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.
Movies
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.
Figures
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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