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Triggered afterslip on the southern Hikurangi subduction interface following the 2016 Kaikōura earthquake from InSAR time series with atmospheric corrections

Lookup NU author(s): Chen Yu, Professor Zhenhong Li, Dr Nigel Penna

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

The 2016 Mw 7.8 Kaikōura earthquake represents an extremely complex event involving over ten major crustal faults, altering conventional understanding of multi-fault ruptures. Although evidence for coseismic slip on the Hikurangi subduction interface is controversial, we present afterslip on the subduction zone beneath Marlborough using 13 months of Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) observations. The spatially and temporally correlated atmospheric errors in SAR interferograms are problematic, and hence a new InSAR time series approach, combining the Generic Atmospheric Correction Online Service (GACOS) with a spatial-temporal Atmospheric Phase Screen (APS) filter to facilitate the InSAR time series analysis, is developed. For interferograms with over 250 km spatial extent, we achieve a 0.77 cm displacement RMS difference against GPS, improving 61% from the conventional InSAR time series method (TS). Comparisons between the overlapping region of two independent tracks show an RMS difference of 1.1 cm for the TS-GACOS-APS combined method, improving 54% from the TS method and 27% from using TS with an APS filter only. The APS filter reduces the short wavelength residuals substantially, but fails to remove the long wavelength error even after the ramp removal, revealing that the GACOS correction has played a key role in mitigating long wavelength atmospheric effects. The resultant InSAR displacements, together with the GPS displacements, are used to recover the time-dependent afterslip distribution on the Hikurangi subduction interface, which provides insights for reviewing the co-seismic slip sources, the present status of the subduction plate boundary and future seismic hazards.


Publication metadata

Author(s): Yu C, Li Z, Penna NT

Publication type: Article

Publication status: Published

Journal: Remote Sensing of Environment

Year: 2020

Volume: 251

Print publication date: 15/12/2020

Online publication date: 28/09/2020

Acceptance date: 11/09/2020

Date deposited: 22/10/2020

ISSN (print): 0034-4257

Publisher: Elsevier

URL: https://doi.org/10.1016/j.rse.2020.112097

DOI: 10.1016/j.rse.2020.112097


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