HR: 0800h
AN: U51A-0002    [Abstracts]
TI: Preliminary Numerical Simulations of the September 12, 2007 Southern Sumatra Tsunami: Forward Modeling and Comparison With Publicly Available Tsunami Data
AU: Tonini, R
EM: roberto.tonini2@unibo.it
AF: University of Bologna, Department of Physics, Sector of Geophysics, Viale Carlo Berti Pichat, 8, Bologna, 40127, Italy
AU: Tinti, S
EM: stefano.tinti@unibo.it
AF: University of Bologna, Department of Physics, Sector of Geophysics, Viale Carlo Berti Pichat, 8, Bologna, 40127, Italy
AU: * Armigliato, A
EM: alberto.armigliato@unibo.it
AF: University of Bologna, Department of Physics, Sector of Geophysics, Viale Carlo Berti Pichat, 8, Bologna, 40127, Italy
AU: Pagnoni, G
EM: gianluca.pagnoni3@unibo.it
AF: University of Bologna, Department of Physics, Sector of Geophysics, Viale Carlo Berti Pichat, 8, Bologna, 40127, Italy
AU: Zaniboni, F
EM: filippo.zaniboni@unibo.it
AF: University of Bologna, Department of Physics, Sector of Geophysics, Viale Carlo Berti Pichat, 8, Bologna, 40127, Italy
AB: An earthquake of magnitude Mw=8.4 (USGS source) was registered on September 12, 2007 offshore the southern coasts of Sumatra, Indonesia. The epicenter was located about 130 km offshore the city of Bengkulu. The earthquake generated a tsunami which, according to some preliminary surveys posted on the Internet by the Indonesian BMG, produced significant damage especially in a region north of Bengkulu, with maximum run-up of 3.6 m in Muko-Muko. The tsunami was also recorded by a number of "tsunameter" stations (including DART) all over the Indian Ocean, including some stations along the coast of Sumatra itself, like Padang. The aim of the present study is to perform some forward modeling of the tsunami and to try to put some constraints on the position and geometry of the causative fault. We basically follow a trial-and-error procedure by adopting some initial fault models, all sharing the same magnitude (provided by the Harvard Moment Tensor Solution), but being different as regards the position and the geometry, including possibly some slight variations of the focal parameters with respect to the solution provided by the Harvard CMT. For each fault choice, we simulate the ensuing tsunami and compare the obtained results with the available experimental data, and in particular with the available tide-gauge records in the Indian Ocean and the run-up measurements that will possibly be collected in the close future. As for the models adopted, we formulate the simple hypothesis that the tsunami initial condition coincides with the coseismic vertical displacement component of the ocean floor, which in turn is computed by means of the classical elastic half-space approach. The propagation of the tsunami is simulated through the numerical finite- differences code UBO-TSUFD, developed by the Tsunami Research Team at the University of Bologna (Italy), which solves the linear Navier-Stokes equations in the shallow-water approximation and in spherical coordinates, and is especially suited to study the tsunami propagation features in the open ocean. To study the tsunami impact close to the source region, and in particular the distribution of observed run-ups, we use the finite-element code UBO-TSUFE, developed by the same research team.
DE: 0468 Natural hazards
DE: 0545 Modeling (4255)
DE: 4564 Tsunamis and storm surges
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Union [U]
MN: 2007 Fall Meeting