Site-Specific Probabilistic Seismic-Hazard Assessment: Direct Amplitude-Based Approach

Abstract

Conventional probabilistic seismic-hazard assessment (PSHA) is difficult to apply in regions lacking sufficient information concerning geological setting, active faults, and so forth. Also, for a PSHA, site effects arising from both crustal rock and overlying soil sediments are generally not assessed rigorously. This is of particular importance for those metropolitan cities having a significant proportion of reclaimed land, because the site-to-site variability of such site effects can be very large. The objective of this article is to demonstrate an alternative procedure for assessing seismic hazard, developed from the conventional source-based Cornell-McGuire PSHA approach, based on considering an infinite number of sources. The proposed new procedure is termed the direct amplitude-based (DAB) approach. The major advantage of the proposed DAB approach is that it is not necessary to characterize any seismic sources. Moreover, if a site-specific and event- specific ground-motion attenuation model is available, a more accurate PSHA could be performed. Also, a generic analytical solution for the proposed procedure has been derived to avoid the need for a lengthy integration process. Using the proposed approach, peak ground velocities have been computed at different return periods, to form a seismic hazard curve, citing Hong Kong as a case study.