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 1817
Numerical experiment of the oil spread caused by the 1964 Niigata
Earthquake Tsunami
Dr. Yoko Iwabuchi
Civil Eng. Tohoku Univ.
Shun-Ichi Koshimura, Fumihiko Imamura
A complex tsunami damage involving floating objects driven by a tsunami is a new aspect of tsunami
disaster in industrialize coastal region. The most commonly observed feature of this complex tsunami
disaster is that the destruction of storage of flammable materials by collision with tsunami-driven
objects or by the hydrodynamic force of tsunami may result spread of large fires, flammable materials
such as spilled oil and ignited material advected and diffused by the tsunami current in a harbor or on
inundated land. In the 1964 Niigata Earthquake,oil were leaked from tanks in coastal industrial region.
The tsunami inundation flow which was happen subsequently cause expansion of oil spreading and fire
damage(Iwabuchi et al. 2006). Despite of the risk of all industrialize coastal region and the
significance of the damage by tsunami, little has been done on estimating the complex damage to
waterfronts. Current situation of estimatiing tsunami damage is based only on counting assets possibly
exposed in a tsunami inundation zone, so the features of complex tsunami disaster is not well
understood. We have developed the water-oil 2-layer model to draw up disaster-affected scenario for
disaster prevention planning or as a tool for designing of oil dike. Here, we conduct a numerical
experiment of the oil spread caused by the past tsunami event. Firstly, the simulation of propagation
and run-up for the 1964 Niigata Earthquake tsunami was carried out. Most fault parameters were based
on the source mechanism proposed by Aki (1966). Two large rivers, the Shinano and Agano, in the
devastated area are vital for determining tsunami devastation, especially the area above the Agano
River mouth, where bathymetry data must be extremely precise to calculate the tidal level at the
Matsugasaki Station during the event. The model tsunami shows good agreement with tidal records.
However, calculated inundation area was underestimated. The ignorance of the remarkable subsidence
caused by liquefaction and fountain flow is likely to be one of the main causes of that underestimation.
The findings suggest that the subsidence caused by liquefaction should be considered to predict
tsunami inundation area. Using both numerical analysis of 1-layer tsunami model and historical records
enables us to confirm that tsunami inundation flow make the oil spreading area more extensive in the
coastal industrial region. Secondly, we take the 1964 Niigata Earthquake Tsunami as an example,
numerical experiments were carried out to apply our 2-layer model. We proposed the processes that oil
layer was transported by tsunami inundation flow. The practical issues were clarified by numerical
simulation for examples.
Keywords: tsunami, 2 layer, oil