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Objectives: Two earthquakes with a distance less than 40 km occurred in Menyuan, Qinghai Province, China, including Mw 5.9 earthquake on 26th January 2016 and Mw 6.7 earthquake on 8th January 2022. Methods: The interferometric synthetic aperture radar (InSAR) technique was utilized to process Sentinel-1A radar images from both ascending and descending tracks to retrieve high resolution coseismic surface displacement maps for these two Menyuan earthquakes. The coseismic surface displacements were then inverted to determine the fault geometry parameters and the non-uniform fault slip distributions with a dislocation model in an elastic half- space. Results: The results show that the 2016 Menyuan earthquake was a reverse event on a buried fault with a maximum surface displacement of 6.7 cm and 7.0 cm on the ascending and descending tracks, respectively. The maximum slip on the fault plane reached 0.53 m and concentrated at depths of 4 − 12 km. The 2022 Menyuan earthquake ruptured along the NWW - SEE strike with a maximum surface displacement of 78 cm in the satellite radar line of sight and a maximum fault slip of 3.5 m occurred at a depth of approximately 4 km. Conclusions: Considering the tectonic settings around the Lenglongling fault zone, the 2022 Menyuan earthquake is likely to occure in the western segment of the left‐lateral Lenglongling fault, with its western end extending westward to the Tuolaishan fault. By calculating the coulomb failure stress changes (CFS), it is inferred that the 2016 Menyuan earthquake generated considerable positive CFS which might have triggered the 2022 Menyuan earthquake. [ABSTRACT FROM AUTHOR]

Surface ruptures and deformation of large earthquakes are important for investigating earthquake mechanisms, fault activities and continental deformation. With the improvement of satellite techniques, op‐ tical and radar images have been widely used in earthquake studies since the 1992 Landers earthquake. However, due to a lack of pre ‐earthquake images, historical earthquakes prior to the 1990s are rarely studied. Recent declassification of American KeyHole (KH) satellite images opened up new possibilities of investi‐ gating old earthquakes back to the 1970s. Researchers have successfully applied KH ‐9 images to the 1978 Tabas‐e‐Golshan and 1979 Khuli‐Boniabad earthquakes in Iran, and gained some new insights into fault be‐ haviours. We first provided a review of the methodology and progresses of using KH ‐9 images to measure earthquake deformation, then investigated the 1976 Chaldiran, Turkey earthquake by matching the pre ‐ and post‐earthquake KH ‐9 images,and obtained an E ‐W displacement of about (3.1±0.7) m (i.e. strike‐slip), consistent with the measurements in the field. KH ‐9 imagery provides a new means of investigating histori‐ cal earthquakes in detail, but there are some limitations. These limitations are briefly discussed in the end. [ABSTRACT FROM AUTHOR]

Landslide is the second only to earthquake as one of the most serious geological hazards， which occur most frequently and cause the most serious losses. It poses a great threat to people9 s lives and property safety. In order to monitor dangerous landslides dynamically, GPRI-II groundbased radar system is used in this experiment to study the key technology of landslide deformation time series analysis, and the main process of ground-based radar data time series processing is formulated. It is applied to the stability monitoring of a road slope in Shaoxing，Zhejiang Province. The experimental results show that there is an obvious deformation area in the slope，which is located in the accumulation area of the construction site，and the maximum deformation is 3. 5 mm/d. At present，ground-based radar has the ability to monitor deformation with sub-millimeter accuracy when the observation conditions are satisfied. Ground-based radar has become one of the important means of disaster early warning and control. [ABSTRACT FROM AUTHOR]