The 28 September 2018 Mw 7.5 Palu earthquake occurred at a triple junction zone where the Philippine Sea, Australian, and Sunda plates are convergent. Here, we utilized Advanced Land Observing Satellite-2 (ALOS-2) interferometry synthetic aperture radar (InSAR) data together with broadband regional seismograms to investigate the source geometry and rupture kinematics of this earthquake. Results showed that the 2018 Palu earthquake ruptured a fault plane with a relatively steep dip angle of ~85°. The preferred rupture model demonstrated that the earthquake was a supershear event from early on, with an average rupture speed of 4.1 km/s, which is different from the common supershear events that typically show an initial subshear rupture. The rupture expanded rapidly (~4.1 km/s) from the hypocenter and propagated bilaterally towards the north and south along the strike direction during the first 8 s, and then to the south. Four visible asperities were ruptured during the slip pulse propagation, which resulted in four significant deformation lobes in the coseismic interferogram. The maximum slip of 6.5 m was observed to the south of the city of Palu, and the total seismic moment released within 40 s was 2.64 × 1020 N·m, which was equivalent to Mw 7.55. Our results shed some light on the transtensional tectonism in Sulawesi, given that the 2018 Palu earthquake was dominated by left-lateral strike slip (slip maxima is 6.2 m) and that some significant normal faulting components (slip maxima is ~3 m) were resolved as well.

A nearly 70 yr hiatus of major seismic activity in the central eastern Bayan Har block (BKB) ended on 22 May 2021, when a multislip-peak sinistral strike-slip earthquake struck western Maduo County, Qinghai. This earthquake, which ruptured the nearly 170 km long Kunlun Pass–Jiangcuo fault, is a rather unique event and offers a rare opportunity to probe the mechanical properties of the intraplate lithosphere of the central eastern BKB. Here, we inferred the fault geometry associated with the Maduo earthquake using Interferometric Synthetic Aperture Radar (InSAR), and relocated aftershocks and inverted the slip distribution through InSAR radar phases and range offsets. Our analysis revealed that the geometry of the fault varies along the strike: the southeastern end of the fault dips steeply to the northeast, whereas the northwestern end dips southwestward. Using the combined datasets to constrain a coseismic slip, we found that the 2021 Maduo event was dominated by sinistral strike-slip movement, with a slight normal-slip component at a shallow depth, rupturing the steep-dipping fault for nearly 170 km in length. Five asperities were detected along the fault strike in the shallow crust (0–12 km) with a peak slip of ∼4.2 m corresponding mostly to simple structures, namely, continuous and straight rupture segments, suggesting that the rupture propagated across geometrical barriers in a multiasperity way. Based on an analysis of the strain field and the focal mechanisms of both the 2021 Maduo earthquake and historical earthquakes that have occurred in the BKB, we propose that the fault zones within the BKB can also generate large earthquakes and have the ability to accommodate the ongoing eastward and northeastward penetration of the Indian plate into the Eurasian plate.

Over 1000 earthquakes struck the northwest of Kangding on the Xianshuihe fault in southwest China between 22 and 29 November 2014, including two largest events of Mw 5.9 and Mw 5.6. The hypocenters of 799 relocated earthquakes suggest that two independent main shock‐aftershock subsequences occurred on the Selaha and Zheduotang branches of the Xianshuihe fault, respectively. Fault slip inversion results from one interferometric synthetic aperture radar (InSAR) interferogram (26 September 2014 to 5 December 2014) show that the Mw 5.9 main shock produced a maximum slip of ~0.47 m at the depth of ~9 km. However, there is no distinct slip associated with the Mw 5.6 main shock. The InSAR determined moment is 2.36 × 1018 Nm with a rigidity of 30 GPa, equivalent to Mw 6.2, which is about twofold the total seismic moment of all the recorded earthquakes during the InSAR time span. This large discrepancy between geodetic and seismic moment estimates indicates that there was probably rapid aseismic afterslip in the 2 weeks following the Mw 5.9 main shock. The released seismic energy of this earthquake sequence is far less than the accumulated strain energy since the 1955 M 712 earthquake on the same fault branch, which implies that the seismic risk on the Selaha‐Kangding segment of the Xianshuihe fault remains high.