Source Constraints and Model Simulation of the December 26, 2004, Indian Ocean Tsunami

Abstract

The December 26, 2004 tsunami was perhaps the most devastating tsunami in recorded history, causing over 200,000 fatalities and widespread destruction in countries bordering the Indian Ocean. It was generated by the third largest earthquake on record ͑M w = 9.1-9.3͒ and was a truly global event, with significant wave action felt around the world. Many measurements of this event were made with seismometers, tide gauges, global positioning system stations, and a few satellite overpasses. There were numerous eyewitness observations and video digital recordings of coastal tsunami impact, as well as subsequent coastal field surveys of runup and flooding. A few ship-based expeditions also took place in the months following the event, to measure and map seafloor disturbances in the epicenter area. Based on these various data sets, recent seismic analysis estimates of rupture propagation speed, and other seismological and geological constraints, we develop a calibrated tsunami source, in terms of coseismic seafloor displacement and rupture timing along 1,200 km of the Andaman-Sunda trench. This source is used to build a numerical model of tsunami generation, propagation, and coastal flooding for the December 26, 2004 event. Frequency dispersion effects having been identified in the deep water tsunami wavetrain, we simulate tsunami propagation and coastal impact with a fully nonlinear and dispersive Boussinesq model ͑FUNWAVE͒. The tsunami source is specified in this model as a series of discrete, properly parameterized, dislocation source segments ͓Okada, 1985, Bull. Seismol. Soc. Am., 75͑4͒, 1135-1154͔, triggered in a time sequence spanning about 1,200 s. ETOPO2's bottom bathymetry and land topography are specified in the modeled ocean basin, supplemented by more accurate and denser data in selected coastal areas ͑e.g., Thailand͒. A 1 min grid is used for tsunami simulations over the Indian Ocean basin, which is fine enough to model tsunami generation and propagation to nearshore areas. Surface elevations simulated in the model agree well, in both amplitude and timing, with measurements at tide gauges, one satellite transect, and ranges of runup values. These results validate our tsunami source and simulations of the December 26, 2004 event and indicate these can be used to conduct more detailed case studies, for specific coastal areas. In fact, part of the development of our proposed source already benefitted from such regional simulations performed on a finer grid ͑15 s͒, as part of a Thailand case study, in which higher frequency waves could be modeled ͑Ioualalen et al. 2006, J. Geophys. Res., in press͒. Finally, by running a non-dispersive version of FUNWAVE, we estimate dispersive effects on maximum deep water elevations to be more than 20% in some areas. We believe that work such as this, in which we achieve a better understanding through modeling of the catastrophic December 26, 2004 event, will help the scientific community better predict and mitigate any such future disaster. This will be achieved through a comb...

Tsunami propagation modelling – a sensitivity study

“…However, time lags of 6-10 min are observed at other station. Similar time lags were shown in the comparison of FUNWAVE's result and measurement in Grilli et al (2007).…”

“…An interesting conclusion from his study is that numerical dispersion in coarser grid made the solution better than higher-order model with the same grid length and even the same model at finer grid. Recently, Grilli et al (2007) compared numerical results of NSWE and Boussinesq simulations for the Indian Ocean (2004) Tsunami. Their study showed a remarkable difference of surface elevation (∼20%) west of the source, in deep water.…”

“…The version of TUNAMI-N2 code that uses NSWE in spherical coordinates with Coriolis terms serves as a control model, and computed maximum tsunami amplitude is compared with the control model. The case study of Indian Ocean Tsunami (2004) event utilizes source estimation by Grilli et al (2007) with minor changes to find the best fit.…”

Pressure field induced in the water column by acoustic‐gravity waves generated from sea bottom motion

“…Due to the complexity of the physical processes of the seismic source, describing the bottom motion becomes rather challenging [Banerjee et al, 2005;Ammon et al, 2005;Pietrzak et al, 2007;Grilli et al, 2008], and simulating the dynamical processes in the tsunami and AGWs source becomes complicated [Nosov and Kolesov, 2007]. Notwithstanding, it is known that properties of AGWs depend on rupture model parameters such as the vertical and lateral extent and duration of bottom motion [Yamamoto, 1982;Nosov, 1999;Chierici et al, 2010;Stiassnie, 2010;Hendin and Stiassnie, 2013].…”

Inventory of uncertainties associated with the process of tsunami damage assessment on buildings (SCHEMA FP6 EC co-funded project)

“…The variation (uncertainty) in the output of a numerical model can be apportioned, qualitatively or quantitatively, through a sensitivity analysis, to different sources of variation in the input of the model. The publications about this type of analysis are numerous (e.g., Weisz and Winter, 2005;Grilli et al, 2007;Dao and Tkalich, 2007;Synolakis et al, 2007;Hébert et al, 2007).…”