Abstract
This study investigates the impact of model complexity in source characterization and digital elevation model (DEM) resolution on the accuracy of tsunami hazard assessment and fatality estimation through a case study in Padang, Indonesia. Two types of earthquake source models, i.e. complex and uniform slip models, are adopted by considering three resolutions of DEMs, i.e. 150 m, 50 m, and 10 m. For each of the three grid resolutions, 300 complex source models are generated using new statistical prediction models of earthquake source parameters developed from extensive finite-fault models of past subduction earthquakes, whilst 100 uniform slip models are constructed with variable fault geometry without slip heterogeneity. The results highlight that significant changes to tsunami hazard and fatality estimates are observed with regard to earthquake source complexity and grid resolution. Coarse resolution (i.e. 150 m) leads to inaccurate tsunami hazard prediction and fatality estimation, whilst 50-m and 10-m resolutions produce similar results. However, velocity and momentum flux are sensitive to the grid resolution and hence, at least 10-m grid resolution needs to be implemented when considering flow-based parameters for tsunami hazard and risk assessments. In addition, the results indicate that the tsunami hazard parameters and fatality number are more sensitive to the complexity of earthquake source characterization than the grid resolution. Thus, the uniform models are not recommended for probabilistic tsunami hazard and risk assessments. Finally, the findings confirm that uncertainties of tsunami hazard level and fatality in terms of depth, velocity and momentum flux can be captured and visualized through the complex source modeling approach. From tsunami risk management perspectives, this indeed creates big data, which are useful for making effective and robust decisions.
Highlights
Recent advances in geosciences have drastically enhanced the accuracy of numerical simulations of complex natural phenomena, such as earthquake rupture processes and consequent earthquake motions and tsunamis (Wang et al, 2015; Ismail-Zadeh et al, 2017)
The improvements lead to sophistication in earthquake source modeling and availability of high-resolution bathymetry and digital elevation models (DEMs), which enhance the quality of tsunami simulations (Ridente et al, 2014; Ramírez-Juidías et al, 2017)
Results from the Monte Carlo tsunami simulation based on the generated earthquake source models can be used to produce probabilistic tsunami hazard results in a region of interest and further used for risk assessment
Summary
Recent advances in geosciences have drastically enhanced the accuracy of numerical simulations of complex natural phenomena, such as earthquake rupture processes and consequent earthquake motions and tsunamis (Wang et al, 2015; Ismail-Zadeh et al, 2017). The improvements lead to sophistication in earthquake source modeling and availability of high-resolution bathymetry and digital elevation models (DEMs), which enhance the quality of tsunami simulations (Ridente et al, 2014; Ramírez-Juidías et al, 2017). These progresses in turn have promoted more rigorous treatment and visualization of uncertainties associated with tsunami disaster risk management. Among the three key elements of tsunami risk, tsunami hazard assessment can be carried out in three stages: tsunami source modeling, propagation, and inundation (Srisutam and Wagner, 2010; Sleeter et al, 2017). Given accurate offshore bathymetry data, e.g. GEBCO and SRTM15-plus, propagation components involve relatively less uncertainties and can be regarded as solved problems (Feng et al, 2017)
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