Based on magnetotelluric array data and the three‐dimensional (3D) inversion algorithm, we obtain the 3D electrical structure of the 1976 Ms7.8 Tangshan earthquake zone. The seismogenic structure comprised a thick resistive anomaly located east of the Tangshan fault (TSF), a thin resistive belt extending westward, and the TSF zone. A geodynamic model is proposed based on the 3D electrical model and the other research findings. The model indicates that the primary cause of the Tangshan earthquake was the almost EW‐trending horizontal pushing from the west. The local uplift of deep thermal materials on the west side of TSF produces tensile deformation superimposed on the existing shear deformation. The combined effect of these two forces controls the Tangshan earthquake deformation characteristic. Prevailing horizontal pushing from the west and local uplift of hot material may be associated with the Tibet Plateau's eastward escape and the subduction of the Pacific plate.

The 2024 Feidong earthquake swarm (maximum magnitude M 4.7) in the seismically quiet Hefei segment of the Tanlu fault zone (TLFZ) raises critical questions about its potential for larger earthquakes. We conducted 3D magnetotelluric imaging to obtain the crustal resistivity structure of the Hefei segment of the TLFZ. The results reveal a large-scale, Tanlu high-resistivity belt (TLRB) along the fault. Its southern segment (R1S) acts as a giant, rigid barrier that inhibits dextral strike-slip motion on the TLFZ. The Feidong earthquake swarm occurred in the structurally weak zone on the western flank of the central TLRB, near the western branch of the TLFZ. A local barrier effectively impeded northeastward rupture propagation. It shares geometric similarities with some seismogenic asperities observed in other strong earthquakes. However, the persistently low fault activity and seismic energy release indicate that current regional tectonic stresses are insufficient to overcome this local barrier, suggesting a low risk of strong earthquakes.

The Nankou–Sunhe Fault is an important NW-trending buried active fault in the Beijing Plain. Its near-surface structure is difficult to identify because of thick Quaternary cover and weak geomorphic expression. In this study, controlled-source radio-magnetotelluric (CSRMT) data were acquired around the Baishan paleoseismic trench, where fault-related deformation has been directly exposed. A total of 61 sites were measured at 17 frequencies between 15 and 450 kHz. After quality screening, 58 sites were retained for 3D inversion. A terrain-constrained three-dimensional resistivity model was obtained after data quality control, apparent resistivity–phase analysis, and 3D inversion. The model shows an overall high–low–high resistivity pattern from shallow to deeper levels. Fault-related markers are directly exposed on both trench walls and were positioned by RTK. At those independently measured positions, the vertical sections of the 3D resistivity model show an electrical gradient zone, supporting the use of CSRMT to locate the electrical expression of the known fault. A broader conductive anomaly occurs near Site 011. The conductive feature may reflect fault-related deformation superimposed on water-bearing and fine-grained Quaternary sediments; the electrical data alone do not distinguish these contributions uniquely. These results demonstrate that CSRMT can delineate the electrical expression of a buried active fault and provide continuous subsurface constraints beyond trench-scale geological observations, although fault activity and kinematics should still be constrained mainly by trenching, drilling, seismic profiling, and chronological evidence.