InSAR Observations Reveal Variations in Shallow Creep on the Kangding Segment of the Xianshuihe Fault

Abstract

AbstractInvestigating the spatiotemporal characteristics of aseismic shallow creep provides insights into interseismic steady-state and/or postseismic transient behavior of faults. In this study, we focus on the Kangding segment of the Xianshuihe fault in eastern Tibet, where the 2014 Mw 5.9 Kangding earthquake occurred. Previous geodetic observations in 1999–2021 identified apparent shallow creep along this segment; however, whether the aseismic slip is secular creep, afterslip of the 2014 Kangding earthquake, or the combined effect remains unresolved. We process descending and ascending Interferometric Synthetic Aperture Radar data in the 2014–2021 period and investigate the creep rate variations on the fault plane. Our results reveal an ∼55-km-long aseismic slip section between Huiyuan Temple and Kangding Airport, of which the ∼15-km-long section between Huiyuan Temple and Jinlong Temple is in steady creep at a rate of 13 ± 2.0 mm/yr. Along the remaining ∼40-km-long section that overlaps the rupture of the Kangding earthquake, the creep rate decays from ∼40 to 0 mm/yr between 2014 and 2019, implying that the aseismic slip here is most likely the postseismic afterslip. We also identify a northwestward migration of aseismic creep from Huiyuan Temple to Longdengba during 2017–2021, which might be related to fluid diffusion. On the basis of the aseismic slip distribution, we quantitatively calculate the moment budget on the Kangding segment. The results show that the Huiyuan Temple-Longdengba section can produce an Mw 6.9 earthquake. Despite the 2014 Kangding earthquake, which ruptured the ∼40-km-long Jinlong Temple-Kangding Airport section, the accumulated seismic moment since the last major earthquake in 1748 is still sufficient for an Mw 7.0 earthquake.