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Continued Work on a Geodetic Strain Rate and Slip Deficit Rate Model for New Zealand

Data-based fault slip rates are key inputs into national seismic hazard models: they are one of several "budgets" that help constrain the likelihoods of large earthquakes at each location. In regions featuring subduction zones, such as Aotearoa New Zealand, there are (in one sense) three kinds of faults to worry about: upper-plate faults, subduction interfaces, and intraslab/outer-rise faults. Slip rates in the first two regimes can be constrained by data. The 2022 revision of the New Zealand National Seismic Hazard Model (NZ NSHM 2022) included two alternate models for upper-plate fault slip rates, one based on geologic data and one based on geodetic data. The geodesy-based model itself included four alternative strain rate models and made use of a novel method to invert surface strain rates directly for slip deficit rates in a way that obviates the need to connect all of the faults as block boundaries. The NZ NSHM 2022 also included two geodesy-based models of coupling on the Hikurangi-Kermadec subduction zone (respectively featuring full locking and no locking at the offshore subduction trench). We are now working on improving this model by adding new data in slow-deforming regions (Auckland/Northland and Southland/Otago), vertical deformation rates, InSAR data (where possible), and improvements to methods (e.g. accounting for uncertainty in fault geometry, and the trade-offs between subduction and upper-plate coupling in terms of their effect on the velocity field).

Session: The 2023 USGS National Seismic Hazard Model and Beyond - II

Type: Oral

Room: Tikahtnu Ballroom A

Date: 5/1/2024

Presentation Time: 11:00 AM (local time)

Presenting Author: Chris Rollins

Student Presenter: No

Additional Authors