Chapter 17 Computational Disaster Mitigation and Reduction Research Unit

Computational disaster mitigation and reduction research unit is aimed at developing advanced largescale numerical simulation of natural disasters such as an earthquake, tsunami and heavy rain, for Kobe City and other urban areas in Hyogo Prefecture. Besides for the construction of a sophisticated urban area model and the development of new numerical codes, the unit seeks to be a bridge between Science and Local Government for the disaster mitigation and reduction. Our research unit addressed the following research objects in this fiscal year: 1) Construction of next generation hazard map for Kobe City. For two scenarios of Nankai Trough Earthquake presumed by National Government, the unit constructed next generation hazard map for Kobe City. Unlike conventional hazard map, the next generation hazard map is based on large scale numerical simulation of the physical processes of seismic wave propagation and seismic structural responses. The map achieves highest spatial resolution as well as higher rationality. Urban area models of Kobe City for underground and man-made structures are used in the physical simulation, and it is these models that determine the quality of the simulation; a more accurate model makes a more reliable estimation of earthquake hazard and disaster. Computational Disaster Mitigation and Reduction Research Unit develops a system that automatically constructs the urban area models using available data resources such as commercial Geographical Information System and governmental data. The system is designed to have high flexibility and expandability so that it can be used for various urban area to which suitable data resources are available. 2) Development of system for liquefaction occurrence estimation. Due to complicated processes, the liquefaction occurrence ought to be estimated by using empirical equations that use engineering indices of soil layers of a target site. Computational Disaster Mitigation and Reduction Research Unit constructs a system that estimates the liquefaction occurrence using numerical simulation of the processes of liquefaction, i.e. coupling of soil deformation and underground water flow induced by ground motion. The system succeeds to automatically generate an underground model for 10,000 sites in Kobe City using available boring data and to simultaneously estimate the liquefaction occurrence for a measured or presumed ground motion. 3) Estimation of lifeline damage induced by earthquake. Lifeline, or a network of buried pipelines of energy, water and communication, is an essential part of an urban area. Lifeline is damaged by ground deformation or strain, rather than ground motion such as acceleration or velocity, and hence