IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS002 Poster presentation 1819
Development of numerical tsunami simulation technique in near field
Mr. Shusaku Inoue
Interdisciplinary Graduate School of Science and T Tokyo Institute of Technology IASPEI
Gota Kubo, Tatsuo Ohmachi
People living in costal areas of Japan are always exposed to tsunami risks because Japan has a long
costal line and active seismicity. And seismic faulting in and around Japan often takes place very close
to the coastline, and tsunamis would attack coastal cities within a few minutes. And also not a few cities
may be included in tsunami source areas. Accordingly, we think it necessary to consider dynamic effects
of tsunami generation followed by propagation and runup. Up to now, many researchers have
investigated tsunami behaviors by means of experiments and computer simulations. Among them, lots
of computer simulations have been carried out for not only academic but also practical purposes, and
lots of simulation techniques have been developed. From an engineering viewpoint, there seems to be
few techniques that can successfully simulate the near field tsunami. For this reason, we have
developed a new technique called dynamic tsunami simulation. Our developed simulation technique was
intended to apply near field tsunamis. The technique consists of two steps of simulation. The first is to
simulate seabed displacements. The boundary element method (BEM) is employed here because it can
give us time histories of dynamic displacement of irregular seabed resulting from a seismic faulting with
a satisfactory level of accuracy. The second is to simulate seawater disturbance using the finite
difference method (FDM). In the second simulation for fluid domain, the Navier-Stokes equation is used
as a governing equation. Thus, this simulation can take account of dynamic ground motion effects in
the tsunami generation. We have recently added new functions to our previous technique to make it
more useful. The new functions are, for example, a technique to simulate tsunami runups, and also a
nesting technique to deal with a large area effectively with a sufficient accuracy. In our technique, the
SOLA procedure and the height function are used. We have validated our technique by comparing
simulation results with runup height of solitary wave derived from theoretical and experimental results.
After all, we have found that our newly developed technique works well, especially for near-field
tsunamis.
Keywords: tsunami simulation, dynamic ground motion, near field