Bayesian Inference of Fault Slip and Coupling Along the Tuosuo Lake Segment of the Kunlun Fault, China

Abstract

Integrating newly‐processed Interferometric Synthetic Aperture Radar (InSAR) and available Global Positioning System (GPS) data, we obtained a dense interseismic velocity field across the Tuosuo Lake segment of the Kunlun fault. Using a Bayesian approach, we obtained the spatial distribution of fault slip and coupling. The slip rate below the locking depth, which represents contemporary steady‐state faulting, demonstrates an overall decrease, and decreases non‐monotonically toward the eastern fault tip in the range of ∼5–11 mm/a. Two strongly locked zones are identified, extending 100–120 km along‐strike and being separated by narrow sections of moderate coupling. These locked zones were likely ruptured during the 1937 M 7.5 Huashixia earthquake. The estimated moment accumulation rate provides a recurrence time of 428 ± 57 years for an earthquake similar to the 1937 event. The Maduo Mw 7.3 earthquake on 21 May 2021 imposed stress loading on the locked zones, equivalent to tectonic loading of ∼10 years, implying increased seismic hazard along the Kunlun fault.

An Updated Fault Coupling Model Along Major Block‐Bounding Faults on the Eastern and Northeastern Tibetan Plateau From a Stress‐Constrained Inversion of GPS and InSAR Data

“…The Riyueshan fault is characterized by a high coupling ratio (0.9-1) along the entire fault, while the Elashan fault is featured by notable low fault coupling along the central part of this fault. The fault coupling pattern along the Elashan fault is consistent with the previous study of Jian et al (2020), in which the fault coupling model is constrained by interseismic GPS data only. The segment ruptured during the 2001 Kokoxili earthquake includes the Taiyanghu fault, the Kusaihu fault, and the western segment of the Kunlun Pass fault.…”

Coseismic Slip Model of the 2022 Mw 6.7 Luding (Tibet) Earthquake: Pre‐ and Post‐Earthquake Interactions With Surrounding Major Faults

“…(2017) and the practice of Jian et al. (2022). In this scenario, shear stress rate on the brittle portion of the fault is equivalently caused by slip deficit of locked asperities.…”

“…To investigate the stress state of the Moxi fault before the Luding earthquake, we calculate the interseismic shear stress rate on the MAF following the method proposed by Wedmore et al (2017) and the practice of Jian et al (2022). In this scenario, shear stress rate on the brittle portion of the fault is equivalently caused by slip deficit of locked asperities.…”

Interseismic Coupling, Asperity Distribution, and Earthquake Potential on Major Faults in Southeastern Tibet

“…This spatial correlation has been demonstrated in multiple large earthquakes such as the Mw 9.0 Tohoku‐Oki (Hashimoto et al., 2009; Loveless & Meade, 2011b), Mw 8.8 Maule (Moreno et al., 2010) and Mw 7.9 Wenchuan (Y. L. Li et al., 2018) earthquakes. Interseismic coupling, which represents the percentage of slip deficit with respect to the long‐term tectonic loading of the fault, provides us with a measure to quantify the accumulation of elastic strain on faults (e.g., Graham et al., 2021; Jian et al., 2022; Jolivet et al., 2015; Y. Li, Nocquet, et al., 2021). Specifically, full coupling means that the strain is fully accumulated on the fault, and no coupling corresponds to aseismic creep, hence zero accumulation of elastic strain.…”