STATISTICAL ANALYSIS FOR THE RESULT OF SEISMIC RISK ASSESSMENT OF TOKYO, JAPAN

Tokyo Metropolitan Government (TMG) conducts a community-based seismic risk assessment for all the city-blocks in the Tokyo Metropolis every five years. The seventh seismic risk assessment survey was carried out for two kinds of risks due to earthquakes: building damage due to strong shaking, and fire outbreak and spread. A bedrock motion with the peak ground velocity 30 cm/s was assumed uniformly for all the study areas and site amplification was considered based on topography and subsurface soil type. Building damage due to shaking was evaluated using empirical vulnerability functions. In this paper, a statistical analysis was conducted for the result of the building damage assessment by the TMG. In the multiple regression analysis, the number of severely damaged buildings per unit area was considered as the dependent variable and several explanation (independent) variables were employed, such as the number of buildings for each structural type and construction period, the soil amplification ratio, and the liquefaction susceptibility. The regression analysis was conducted for all the 5,133 city-blocks in the Tokyo Metropolis and an accurate prediction equation was derived