The precise characterization of surface rupture zones and associated co-seismic displacement fields from large earthquakes provides critical insights into seismic rupture mechanisms, earthquake dynamics, and hazard assessments. Stereo-photogrammetric digital elevation models (DEMs), produced from high-resolution satellite stereo imagery, offer reliable global datasets that are suitable for the detailed extraction and quantification of vertical co-seismic displacements. In this study, we utilized pre- and post-event WorldView-2 stereo images of the 2024 Ms7.1 Wushi earthquake in Xinjiang to generate DEMs with a spatial resolution of 0.5 m and corresponding terrain point clouds with an average density of approximately 4 points/m². Subsequently, we applied the Iterative Closest Point (ICP) algorithm to perform differencing analysis on these datasets. Special care was taken to reduce influences from terrain changes such as vegetation growth and anthropogenic structures. Ultimately, by maintaining sufficient spatial detail, we obtained a three-dimensional co-seismic displacement field with a resolution of 15 m within grid cells measuring 30 m near the fault trace. The results indicate a clear vertical displacement distribution pattern along the causative sinistral–thrust fault, exhibiting alternating uplift and subsidence zones that follow a characteristic “high-in-center and low-at-ends” profile, along with localized peak displacement clusters. Vertical displacements range from approximately 0.2 to 1.4 m, with a maximum displacement of ~1.46 m located in the piedmont region north of the Qialemati River, near the transition between alluvial fan deposits and bedrock. Horizontal displacement components in the east-west and north-south directions are negligible, consistent with focal mechanism solutions and surface rupture observations from field investigations. The successful extraction of this high-resolution vertical displacement field validates the efficacy of satellite-based high-resolution stereo-imaging methods for overcoming the limitations of GNSS and InSAR techniques in characterizing near-field surface displacements associated with earthquake ruptures. Moreover, this dataset provides robust constraints for investigating fault-slip mechanisms within near-surface geological contexts.

The Daliangshan Fault Zone (DLSFZ) constitutes a key segment of the Xianshuihe–Xiaojiang Fault System (XXFS) and exerts fundamental control on the eastward extrusion of the Sichuan–Yunnan Block (SYB). In this work, we present new slip rate determinations at three key sites (Tekoujiagu, Yeer, Damulo) along its middle-southern segments using UAV-based high-resolution topography and OSL dating. Results yield late Quaternary slip rates of 4.5 ± 1.4, 3.7 ± 1.1, and 5.5 ± 1.0 mm/a, respectively. Combined with previous data, the slip rate is 1.5–3.1 mm/a in the northern segment, 1.36–4.3 mm/a in the middle and 2.5–4.5 mm/a in the southern segment, which exhibits a spatial pattern of “higher in the south, lower in the north, with transition in the middle”. Temporal evolution suggests increased slip rates from the Late Pleistocene to Holocene. These characteristics indicate that the DLSFZ is a heterogeneous deformation system, where strain focusing on the southern segment reflects the block’s eastward escape constrained by the rigid Sichuan Basin (SB). Thus, the DLSFZ, especially its southern segment, serves as a key structure regulating crustal extrusion at the southeastern margin of the Tibetan Plateau (TP).

Coseismic displacement and deformation patterns near seismic rupture zones are crucial for understanding earthquake rupture processes, fault behaviors, and the relationship between active faults and topographic features. Recent advances in sub-meter accuracy digital terrain data derived from high-resolution optical satellite stereo imagery have provided new geodetic approaches for differential topography studies, including three-dimensional coseismic surface displacement field acquisition. This study generated pre- and post-earthquake topographic point cloud data (average point density: 1.2 points/m²) using GF-7 satellite stereo imagery, and obtained a 25-meter spatial resolution three-dimensional coseismic surface displacement field in the near-fault area of the 2025 Dingri, Tibet Mw7.1 earthquake through a window-based (50-meter window size) Iterative Closest Point (ICP) algorithm. The results reveal that the surface rupture of the Dingri earthquake was dominated by vertical displacement with insignificant horizontal motion, consistent with the focal mechanism solutions and field investigations of the rupture zone. The vertical displacement distribution extracted from ICP displacement field exhibits a "high central section with decreasing values northward and southward" pattern, reaching a maximum vertical displacement of ~2.5 m near the central Nixiacuo area, decaying to ~1.2 m northward and ~0.5 m southward. Compared with field measurements, ICP-derived vertical displacements generally exceed field observations, indicating that surface dislocation markers only reflect the minimum coseismic displacement along the rupture zone. The ICP method quantifies cumulative displacement across hundreds of meters on both sides of the rupture, providing critical constraints for studying shallow slip deficit mechanisms and facilitating future investigations of fault slip transfer processes from deep to shallow levels. This study demonstrates the unique advantages of new high-resolution optical satellites in long-term pre-seismic data accumulation, rapid post-seismic data acquisition, and comprehensive coverage of surface deformation zones. These capabilities enable timely construction of near-field 3D coseismic displacement fields, allowing differential topography techniques to measure 3D coseismic deformation in areas inaccessible for LiDAR surveys. This approach effectively compensates for limitations of conventional InSAR and sub-pixel correlation techniques near surface ruptures, where large deformation gradients or insensitivity to vertical displacements often cause measurement failures.

Global observations reveal faults respond to earthquake ruptures through localized on-fault slip and distributed off-fault deformation (OFD). Deformation becomes increasingly delocalized along faults that are immature or geometrically complex, rupture slowly, or propagate through sediment-rich regions. However, the physical processes by which sediments control this delocalization remain largely unresolved. Here we utilize high-resolution optical imagery to characterize surface rupture and OFD of the 2025 Mw 7.8 Myanmar earthquake, a supershear rupture event on a mature fault topping with thick sediments including the Quaternary alluvium and Irrawaddy Formation. Our results show averaging 32% OFD, far exceeding 13-19% expectation from global observations of such mature faults with simple geometry and supershear rupture speeds. Sediment-rich terrains along this rupture significantly amplify OFD to ~31-42%, nearly double the 19% observed in bedrock, and generate two highly diffused deformation sections lacking clear surface rupture. Dynamic rupture simulations incorporating variations in shear-wave velocity and frictional properties reproduce the observed OFD spectrum (from localized to fully delocalized deformation, revealing that plastic yielding of sediments dramatically delocalizes fault strain in the uppermost few hundreds of meters. We suggest such process should be integrated into models of shallow faulting and seismic hazard assessment in sediment-rich regions worldwide.