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

REMOTE SENSING OF ENVIRONMENT

卷:251

Article

Yu, Chen¹  Li, Zhenhong^1,2  Penna, Nigel T.¹ 

[1] Newcastle Univ, Sch Engn, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England

[2] Changan Univ, Coll Geol Engn & Geomat, Xian 710054, Peoples R China

关键词: InSAR time series;    Atmospheric corrections;    GACOS;    Afterslip;    Hikurangi subduction zone;   

DOI  :  10.1016/j.rse.2020.112097

来源: Elsevier

【 摘 要 】

The 2016 Mw 7.8 Kaikura 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 in-terface, which provides insights for reviewing the co-seismic slip sources, the present status of the subduction plate boundary and future seismic hazards.

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