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 Oral Presentation 1767
Tsunami vulnerability assessment for the city of Banda Aceh using the
tsunami numerical model and the post-tsunami survey data
Dr. Shunichi Koshimura
Graduate school of engineering Tohoku University
Takayuki Oie, Hideaki Yanagisawa, Fumihiko Imamura
The 2004 Indian Ocean tsunami disaster attacked the city of Banda Aceh, Indonesia. According to the
post-tsunami survey conducted by Japan International Cooperation Agency (JICA), this tsunami resulted
more than 70,000 of casualties corresponding to 27 % of population before disaster and more than
12,000 of house damage. The extent of tsunami inundation zone reached approximately 2 km inland
from the shoreline. The present study aims to understand Banda Aceh's vulnerability against the
tsunami disaster, by using the numerical model of tsunami propagation and run-up, and GIS analysis
with post-tsunami survey data in terms of casualties and structural damage. The post-tsunami survey
data were obtained by an effort of JICA mission of the study on the urgent rehabilitation and
reconstruction support program for Aceh province and affected areas in north Sumatra. Using the highresolution
land elevation data, we performed a coastal inundation modeling for the 2004 Indian Ocean
tsunami that attacked the city of Banda Aceh. The model is based on a set of non-linear shallow water
equations with bottom friction in the form of Mannings formula according to the land use condition. The
equations are discretized by the Staggered Leap-frog finite difference scheme. To create the
computational grids for tsunami model, we use the GEBCO digital bathymetry data, SRTM data, local
bathymetric charts of northern Sumatra (1:500,000and 1:125,000) and land elevation data obtained by
digital photogrammetric mapping. The grid size varies from 1860 m to 23 m from the source region to
the coast of Banda Aceh, constructing a nested grid. The Final grid size within the city of Banda Aceh is
23 m, and the data is based on the land elevation data provided by JICA. The model results in terms of
local inundation depth and the extent of inundation zone are consistent with the actually measured and
interpreted data from satellite imagery. Also, using GIS analysis combined with the detailed survey data
in terms of the damage on structures and casualties, we developed the tsunami inundation depthdamage
diagram to understand Acehs vulnerability against tsunami disaster. Throughout the present
analysis, we found that number of destroyed structures and the percentage of casualties significantly
increase for 2 or 3 m as local tsunami inundation depth. In order to reduce the tsunami hazard and
mitigate the damage of possible tsunami disaster, Acehs reconstruction planning should consider the
possible countermeasures such as sea walls or vegetations in order to reduce the local tsunami
inundation depth to at least 2m.
Keywords: tsunami, vulnerability, numericalmodel