The Shanxi Rift System (SRS) is a prominent intracontinental rift in eastern Eurasia. However, its tectonic origin remains enigmatic, as the timing of rift initiation and its subsequent evolution is not well constrained. To evaluate the cooling history of rift flanks, we present joint apatite fission track (n = 15) and apatite (U‐Th‐Sm)/He (n = 62) thermochronological study across the Huo Shan and the Zhongtiao Shan in the central and southern SRS, respectively. Inverse modeling of the thermochronological data yields two episodes of enhanced exhumation during the Cenozoic. Both ranges record rapid cooling circa 50‐35 Ma, coeval with a phase of widespread rifting across entire North China. Data from the Zhongtiao Shan record renewed cooling from ∼8 Ma to the present, following a protracted near‐isothermal condition. Considering the SRS in the context of plate reconstructions, we propose that the Eocene rift initiation is triggered by the subduction of the trench‐parallel Izanagi‐Pacific mid‐ocean ridge followed by subduction of the Pacific plate. Tectonic quiescence along the Shanxi rift during Oligocene and Miocene time reflects slow thermal subsidence as the Pacific subduction regime was established. In late Miocene, faults associated with the SRS were reactivated in dextral transtension linked to fault systems that extend outward from the northeastern Tibetan Plateau. This kinematic reorganization implies a fundamental change in force balance throughout North China. Overall, our results reflect the changing influence of tectonic regimes along the eastern Eurasian plate boundary and intracontinental deformation associated with the India‐Eurasia collision.

The Hongdong earthquake occurred in the Shanxi Graben System, North China, on 25 September AD 1303, and has previously been suggested to be the first M 8 event recorded in China (with ~ 270,000 deaths); if this magnitude estimate is confirmed it would be an unusually large continental normal fault earthquake. The Hongdong earthquake is also important for understanding regional tectonics and seismic risk in North China. We present 31 AMS‐¹⁴C ages to date earthquakes recorded in five trenches, in the Huoshan Piedmont Fault (HPF), which is interpreted to be the causative fault for the Hongdong event. We use high‐resolution imagery to interpret fault traces, and map the Hongdong earthquake surface rupture in detail. Four events are identified with timings constrained at 1060‐590 yr BP (interpreted as the AD 1303 event), ~ 3,310‐3,210 yr BP, < 5,460‐5,380 yr BP, and < 26,380 yr BP, respectively. The later three events have a recurrence interval of ~ 2,000‐3,000 yr. We confirm that the Hongdong earthquake had a rupture length of ~98 km, with representative throw of 3.5 m and a maximum throw of ≤5.0 m. Simple scaling relationships and a moment magnitude scale relationship yield best estimates for magnitude in the range M_w 7.2‐7.6. The derived late Holocene extension rate is ~0.6‐0.9 mm yr^‐1, while the late Pleistocene rate was ~0.14 mm yr^‐1. Previous determination of M 8 was based on shaking intensity and the high reported death toll, and is likely to be an over‐estimate. Normal fault earthquakes have smaller upper limits to their magnitudes than thrusts, because their relatively steep dips produce intersections at the base of the seismogenic layer at smaller down‐dip widths than gently‐dipping thrust faults. The Hongdong event was not an exception to this pattern. The historic released seismic moment may be closer to the accumulated moment than previously calculated.

Assessing the seismic hazard of a fault is usually based on its record of strong earthquakes. Earthquake records with long periods of quiescence for active faults can lead to underestimates of seismic hazards, such as for the Longmenshan fault zone which produced the unanticipated 2008M_w7.9 Wenchuan earthquake. The Daliangshan fault zone has a low slip rate and has not produced any strong earthquakes in history. As a result, little is known about its paleoearthquake history, including the behavior of any strong earthquakes it might produce and the seismic hazards posed by the Daliangshan fault zone. To solve this problem, we excavated four trenches across the Jiaojihe and Butuo faults along the southern segment of the Daliangshan fault zone. The paleoseismic investigations revealed six paleoearthquakes on the Jiaojihe fault in ~20,000 years and determined another seven rupturing events on the Butuo fault in ~42,000 years. The strong earthquake history of the Jiaojihe fault has evidence of temporal clustering, while the Butuo fault exhibits a relatively periodic recurrence pattern with intervals of 1,710–2,460 years. Based on its surface rupture length and the magnitude of observed displacement, the southern segment of the Daliangshan fault zone is capable of producingM > 6.5 earthquakes. Furthermore, based on their respective slip rates and the elapsed times since the most recent events along the Jiaojihe and Butuo faults, they have accumulated seismic energy equivalent toM ~ 7.6, suggesting they pose a significant seismic hazard to the southeastern Tibetan Plateau.