Seismic Hazard Assessment and Site Response Evaluation in Perth Metropolitan Area

摘要

Perth is the capital city of Western Australia, its seismic hazard has in the past been considered to be quite low. However, in recent decades the population and metropolitan area itself has increased considerably. Furthermore, Michael-Leiba (1986) demonstrated that the seismicity to the east of the city had also increased compared with historical times. Hence, both the seismic threat and the vulnerability of Perth Metropolitan Area (PMA) to earthquake damage have significantly increased. During that time interval there has been much research trying to quantify this hazard. As only very limited number of earthquake strong ground motion records are available in southwest Western Australia (SWWA), previous studies of seismic hazard of PMA were predominantly based on the ground motion attenuation model derived from central and eastern North America (CENA). In principle, these adoptions seemed valid because both CENA and SWWA are located in the stable continental intraplate region. However, some bias in prediction for SWWA ground motion and seismic risk may be produced since there are a lot of different factors in different regions, e.g. ground motion characteristics and site conditions. Hence, in this paper, a seismic risk analysis of PMA based on the updated local ground motion attenuation model is performed. Responses of the three site classes in PMA are calculated. The response spectra on rock and soil sites are estimated and compared with the respective design spectrum defined in the Current Australian Earthquake Loading Code. Discussions on adequacy of the design spectrum against that of seismic analysis in this study are made.