Abstract
The potential for future earthquakes on faults is often inferred from inversions of geodetically derived surface velocities for locking on faults using kinematic models such as block models. This can be challenging in complex deforming zones with many closely spaced faults or where deformation is not readily described with block motions. Furthermore, surface strain rates are more directly related to coupling on faults than surface velocities. We present a methodology for estimating slip deficit rate directly from strain rate and apply it to New Zealand for the purpose of incorporating geodetic data in the 2022 revision of the New Zealand National Seismic Hazard Model. The strain rate inversions imply slightly higher slip deficit rates than the preferred geologic slip rates on sections of the major strike-slip systems including the Alpine Fault, the Marlborough Fault System and the northern part of the North Island Fault System. Slip deficit rates are significantly lower than even the lowest geologic estimates on some strike-slip faults in the southern North Island Fault System near Wellington. Over the entire plate boundary, geodetic slip deficit rates are systematically higher than geologic slip rates for faults slipping less than one mm/yr but lower on average for faults with slip rates between about 5 and 25 mm/yr. We show that 70%–80% of the total strain rate field can be attributed to elastic strain due to fault coupling. The remaining 20%–30% shows systematic spatial patterns of strain rate style that is often consistent with local geologic style of faulting.
Recommended Citation
K. M. Johnson et al., "Inverting Geodetic Strain Rates For Slip Deficit Rate In Complex Deforming Zones: An Application To The New Zealand Plate Boundary," Journal of Geophysical Research: Solid Earth, vol. 129, no. 3, article no. e2023JB027565, American Geophysical Union; Wiley, Mar 2024.
The definitive version is available at https://doi.org/10.1029/2023JB027565
Department(s)
Geosciences and Geological and Petroleum Engineering
Publication Status
Open Access
Keywords and Phrases
faults; geodesy; interseismic; inversion; seismic hazard; slip rate
International Standard Serial Number (ISSN)
2169-9356; 2169-9313
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2024 American Geophysical Union; Wiley, All rights reserved.
Publication Date
01 Mar 2024
Comments
U.S. Geological Survey, Grant 2020-BD101