The Hutubi earthquake, which occurred on 8 December 2016 with a moment magnitude of M 6.2, was a pure thrust event in the northern Tian Shan belt. By examining the location of the hypocenter, focal mechanism, regional geology, and artificial seismic reflection profiles, we are able to reveal the structural and sedimentary framework of a section of the northern Tian Shan through seismic interpretation. Our study indicates that the seismogenic fault responsible for the M 6.2 Hutubi earthquake is a thrust fault with a low dip angle of 22° at a depth of $∼16km$⁠. It has a ramp–flat–ramp geometry and is connected to the active Huoerguosi–Manas–Tugulu fault (F3) at the surface. Accumulated total stratigraphic offset at fault F3 is $∼5.8km$ with a fault shortening of $∼5.4km$⁠. This gives a shortening rate of $∼0.9mm/yr$ between the Qigu and Tugulu anticlines during the Late Cenozoic. Based on regional study of the fault plane, fault F3 is capable of producing earthquakes of $Mw≥8.0$⁠. This study suggests that fault F3 was the seismogenic fault responsible for the 2016 M 6.2 Hutubi earthquake and the 1906 M 7.7 Manas historical earthquake. The active fault system in the northern Tian Shan belt was involved in fault‐related folding during the Late Cenozoic and therefore poses a potential seismic hazard in the study area.

On 3 July 2015, the M_w 6.5 Pishan earthquake occurred in the western Kunlun Mountains front, at the northern margin of the Tibetan Plateau. To reveal the sedimentary-tectonic framework of the seismically active structure, three high-resolution seismic reflection profiles and well drilling data were collected for seismic interpretation. The western Kunlun Mountains and Tarim Basin have two gypseous detachments and one basement detachment that control the tectonic framework and structural deformation. The upper gypseous detachment (D1) is in the lower Paleocene, and the middle gypseous detachment (D2) is in the Middle to Lower Cambrian. A Neogene shallow thrust system is developing above D1 and includes the Zepu fault (F2) and Mazar Tagh fault (F3). A deep thrust system is developing between D1 and D2 and forms a large-scale structural wedge beneath the western Kunlun Mountains front. The Pishan M_w 6.5 earthquake was triggered on a frontal blind fault of this deep thrust system. The lower detachment is in the Proterozoic basement (D3), which extends into the Tarim Basin and develops another deep thrust (F4) beneath the F3 belt. D1, D2, D3, and the Tiekelike fault (F1) merge together at depth. Crustal shortening of the western Kunlun Mountains front continues for approximately 54 km. Two tectonic evolutionary stages have occurred since the Miocene according to sedimentary unconformity, axial analysis, and fault interpretation. The results of this study indicate a regime of episodic growth of the western Kunlun Mountains and Tarim Basin during the Cenozoic.

Details of lithospheric structures in three‐dimensions (3‐D) are key to understanding the dynamics of crustal deformation and earthquakes in active orogenic systems. In this study, we develop a 3‐D model of the eastern Tibetan Plateau using the Skua‐Gocad software based on the latest Rayleigh wave tomography. We perform a quantitative modeling workflow to map the details of the Moho discontinuities and the high‐velocity anomalies. Then, we integrate the topography, major active faults, large earthquakes, and crustal Poisson's ratios to analyze the relationship between the shallow and deep structures of this region. Our study shows that the Moho is generally coupled with the topography. A steep Moho ramp exists under the plateau margin and its surface projection intersects the Longmen Shan (LMS) at a low oblique angle (~22°). Active deformation and large earthquakes are related to the steep Moho ramp under the plateau margin. Moreover, based on a 3‐D model of the Poisson's ratio perturbations, we find that deformation across the central LMS is characterized as a crocodile‐type wedge in the crust and lithospheric mantle, due to the resistance of the Yangtze craton and isostatic rebound. We suggest that a tectonic wedging model that contains both the upper‐crust thrusting and lower‐crustal thickening contribute to the LMS orogeny. Three‐dimensional visualization of the lithospheric structure is well suited to reveal the different levels of deformation and their relationships. Quantitative modeling methods provide effective constraints on the active blocks in the eastern Tibetan Plateau.