Ground-motion selection for scenario ruptures using the generalized conditional intensity measure (GCIM) approach and its application for several major earthquake scenarios in New Zealand

摘要

Generalized conditional intensity measure (GCIM) method is extended to ground motionselection for scenario ruptures. Using different rupture scenarios and site conditions, variousaspects of the GCIM methodology are scrutinized, including: (i) implementation of differentweight vectors and the composition of the IM vector; (ii) quantifying the importance ofreplicate selections for different number of desired ground motions; and (iii) the effect ofconsidering bounds on the implicit causal parameters of the prospective ground motions.Using the extended methodology, representative ground motion ensembles for several majorearthquake scenarios in New Zealand are developed. Cases considered include representativeground motions for the occurrence of Alpine, Hope, and Porters Pass earthquakes inChristchurch city, and the occurrence of Wellington, Wairarapa, and Ohariu fault ruptures inWellington city. Challenges in the development of ground motion ensembles for subductionzone earthquakes are also highlighted. The selected scenario-based ground motion sets canbe used to complement ground motions which are often selected in conjunction withprobabilistic seismic hazard analysis, in order to understand the performance of structures forthe question “what if this fault ruptures?”