Cybershake NZ v19.5: New Zealand simulation-based probabilistic seismic hazard analysis

Brendon A. Bradley, Jonney Huang, Jason Motha, Karim Tarbali, Robin L. Lee, Sung Bae, V Polak, M Zhu, C Schill, J Patterson, & D Lagrava

Published July 23, 2019, SCEC Contribution #9246, 2019 SCEC Annual Meeting Poster #019

This poster presents the computational components and results of the May 2019 version (v19.5) of probabilistic seismic hazard analysis (PSHA) in New Zealand based on physics-based ground motion simulations (‘Cybershake NZ’). A total of 11,362 finite fault simulations were undertaken and seismic hazard results are computed on a spatially-variable grid of 27,481 stations with distributed seismicity sources considered via conventional empirical ground motion models. In the current work completed to date a NZ-specific modification of the Graves and Pitarka (2010,2015) hybrid broadband ground motion simulation approach was utilized based on improvements identified from extensive validation efforts.  Specific simulation features include a transition frequency of 0.25 Hz, a detailed crustal model (NZVM v2.0) that represents eight distinct sedimentary basins in NZ using a grid spacing of 0.4 km, and an empirically-calibrated local site response model. A Monte Carlo scheme is used to sample variability in the seismic source parametrization (i.e. varying the hypocenter location and slip distribution for each realization) with the total number of ruptures for each source being a function of the source magnitude. The generated uniform hazard maps across the country are presented. Immediate near-term advances associated with crustal velocity modelling, simulation methodology, and treatment of modelling uncertainty are also discussed.

Bradley, B. A., Huang, J., Motha, J., Tarbali, K., Lee, R. L., Bae, S., Polak, V., Zhu, M., Schill, C., Patterson, J., & Lagrava, D. (2019, 07). Cybershake NZ v19.5: New Zealand simulation-based probabilistic seismic hazard analysis. Poster Presentation at 2019 SCEC Annual Meeting.

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