Mingming Jiang

Slab tearing has been increasingly recognized as a key geodynamic process influencing the evolution of the eastern Himalayan syntaxis. However, whether, where and how the subducted Indian slab beneath the Indo‐Myanmar subduction zone has been torn remains poorly constrained. Applying seismic tomography to new wide‐aperture data in and around Myanmar, we image the detailed architecture of the Indian slab. Our results especially show two high‐velocity anomalies with opposing dips in the upper mantle: an east‐dipping anomaly representing the subducting Indian slab and a west‐dipping body preferentially interpreted as a detached slab fragment. The intersection angle between the two anomalies decreases southward, and their along‐dip lengths vary inversely, indicating southward‐shallowing slab tearing likely induced by the oblique subduction setting. Tearing‐induced mantle upwelling may be impeded by the subducting Indian slab at shallow depths and the limited gap between slab segments, likely explaining the sporadic volcanism in Myanmar since the Mid‐Miocene.

Seismological investigations of the uppermost mantle beneath Myanmar are essential for constraining the dynamic processes associated with oblique subduction in this region. We constructed a high‐resolution Pn‐wave velocity and azimuthal anisotropy model using a combined data set of 51,982 high‐quality Pn arrivals, compiled from recordings of three newly deployed temporary seismic arrays and bulletin data from the ISC‐EHB and the National Earthquake Data Center. The velocity model reveals large‐scale high‐velocity anomalies beneath the northeastern margin of the Indian Plate, consistent with underthrusting of cold Indian continental lithosphere. Additional high‐velocity anomalies west of the Kabaw Fault spatially coincide with the geometry of the subducting Indian Plate in the Slab2 model, further supporting ongoing slab penetration. In contrast, a pronounced uppermost mantle low‐velocity zone beneath northern Myanmar suggests localized upwelling of hot mantle material, likely induced by horizontal tearing of the Indian slab and potentially linked to Quaternary volcanism. Beneath the southern Indo‐Burma Ranges, a low‐velocity anomaly with trench‐parallel anisotropy implies antigorite lattice‐preferred orientation. Beneath the Central Myanmar Basin volcanic cluster, an arcuate high‐velocity anomaly is interpreted as relatively cold and dry mantle‐wedge exhumation associated with slab rollback.

Myanmar's high seismic hazard is underscored by the 2025 M _w 7.7 earthquake on the Sagaing Fault, yet its seismicity patterns and underlying controls remain poorly understood. Using new seismic data from the 2nd‐phase array of the China‐Myanmar Geophysical Survey in the Myanmar Orogen, we construct a high‐resolution catalog of 1,819 local‐shallow earthquakes in central and southern Myanmar by combining deep‐learning algorithms and manual phase‐pick refinement, with 93 robust focal mechanisms. Integrated with a previous catalog further north, our analysis reveals that the Sagaing Fault dips eastward at ∼73° in the north, transitions to a nearly‐vertical geometry at ∼20.5°N, and continues further south. This newly identified fault segmentation and associated geometric variations provide essential constraints for improving fine‐scale rupture modelling of the 2025 earthquake. For the whole of Myanmar, our results suggest an abrupt along‐strike north‐south change of shallow seismicity across ∼20°N, with contrasting earthquake distributions and focal mechanisms.

The Eastern Himalayan Syntaxis (EHS) serves as a natural laboratory for the study of intense continental collision and lateral extrusion tectonics. By aiming at the intricate tectonic dynamics south and southeast of the EHS, we integrate seismic data from new broadband stations in central Myanmar with permanent stations in southeastern Tibet to establish a high‐resolution 3‐D shear wave velocity model through ambient noise surface wave tomography. Our imaging results reveal distinct differences in crustal seismic velocity structures between the West Burma Block, Chuan‐Dian Block, and the Shan Plateau, highlighting the extent of oblique subduction and restricted crustal extrusion. Notably, two north‐south oriented low‐velocity zones in the mid‐to‐lower crust of southeastern Tibet are mainly confined within the Chuan‐Dian Block and terminate near the Red River Fault, with limited extension into the Shan Plateau.

The far limit of a plate subduction process and its related far‐field dynamic process are fundamental topics for plate tectonics. The Great Khingan Range (GKAR) in the western flank of NE China is currently under the far‐field influence of the Pacific plate subduction. Benefiting from the newly deployed seismic arrays in the northern GKAR, we take full advantage of seismic data from both temporary and permanent networks and employ an improved scheme of the H‐κ stacking method by introducing surface wave dispersion to obtain the integrated maps of Moho depth and crustal bulk Vp/Vs ratio in this region. Our results show that the Moho depth has a giant step near the North–South Gravity Lineament (NSGL). Meanwhile, the distribution of bulk Vp/Vs ratio presents a north–south difference roughly by 50°N, where the south subregion consists of a collage of high and low Vp/Vs ratio; by contrast, the north subregion is characterized by unified high values. The east‐west structural discrepancies across the NSGL from the Earth's surface to the mantle transition zone indicate the difference in the strength of modifications between the near and far‐fields from the Pacific plate subduction. The complicated distribution of the Vp/Vs ratio in the south subregion supports that secondary small‐scale upwellings underneath the Cenozoic volcanic groups dominate the tectonic reworking in this area. The lack of Cenozoic volcanism and a more straightforward distribution of the Vp/Vs ratio in the north subregion might allude to a tectonically inactive part of NE China.

Myanmar bears a high risk of destructive earthquakes, yet detailed seismicity catalogs are rare. We designed a deep‐learning‐based data processing pipeline and applied it to the data recorded by a large‐aperture (∼400 km) seismic array in central Myanmar to produce a high‐resolution earthquake catalog. We precisely located 1891 earthquakes at shallow (b‐value.

The lithospheric architecture of the South China Block (SCB) is crucial to understanding the formation and evolution of this distinctive and highly reworked continental lithosphere with over 3 billion years of tectonic history. However, due to a lack of high‐resolution geophysical datasets, a detailed picture of the SCB lithosphere is absent, and fundamental questions regarding its formation, assembly, and subsequent reworking processes are actively debated. Assuming that unique deformation patterns due to such tectonic processes can be mapped by seismic anisotropy, we present a new crustal radially anisotropic shear‐wave velocity model along a 1500‐km seismic transect that spans the major tectonic domains of the SCB to characterize the past deformation processes. The new seismic models show significant lateral variations in seismic anisotropy and velocity, suggesting that the SCB consists of several separated (micro)continental blocks or terranes that likely have different origins and have survived the prolonged deformation history since the early formation of these continental fragments. Combining available geophysical datasets, we link individual crustal domains of distinct anisotropy to constrain the multiphase deformation processes of the SCB, including the early formation of the Proto‐Yangtze and Cathaysia Blocks, the assembly of the SCB, and the subsequent reactivation of the interior and extensive deformation that have formed the Basin‐and‐Range style tectonics in the Cathaysia Block. We suggest that relict continental fragments have played critical roles in the formation and reactivation of the SCB lithosphere.

Closure of the Neo-Tethyan Ocean is one of the most significant tectonic events of the Cenozoic, forming the longest continental collision belt on Earth and influencing global climate and biodiversity. However, whether late Mesozoic subduction of the Neo-Tethyan Ocean occurred along one single or a double subduction system remains controversial. Here, upper mantle imaging from seismic tomography and waveform modeling in the Myanmar region reveals two prominent, parallel, slab-like structures with high seismic velocities that trend to the north-south and dip to the east. The western high-velocity zone has been observed previously and represents the modern subducting slab. The eastern zone has not been previously reported and exhibits high-velocity anomalies of 1.0 to 2.5% to a depth of ~300 km. This zone likely represents a remnant of another Neo-Tethyan oceanic slab that subducted ~40 million years ago. Double subduction of the Neo-Tethyan Ocean during the late Mesozoic to early Cenozoic requires reevaluation of previous tectonic models.

This study represents the first campaign‐style teleseismic shear wave splitting (SWS) investigation of central Myanmar, an area that is tectonically controlled by the oblique subduction of the Indian Plate underneath the Eurasian Plate. The resulting 678 well‐defined and 247 null SWS measurements obtained from recently deployed 71 broadband seismic stations show that the Indo‐Burma Ranges (IBR) possess mostly N‐S fast orientations that are parallel to the trend of the depth contours of the subducted slab. Relative to the global average of 1.0 s, extremely large splitting times with station‐averaged values ranging from 1.28 to 2.79 s and an area‐averaged value of 2.09 ± 0.55 s are observed in the IBR. In contrast, the Central Basin (CB) and the Shan Plateau (SP) are characterized by slightly larger than normal splitting times. The fast orientations observed in the CB are mostly NE‐SW in the northern part of the study area, N‐S in the central part, and NW‐SE in the southern part. The fast orientations change from nearly N‐S along the N‐S oriented Sagaing Fault, to NW‐SE in the central and eastern portions of the SP. These observations, together with SWS measurements using local S events, crustal anisotropy measurements using P‐to‐S receiver functions, and the estimated depth of the source of anisotropy using the spatial coherency of the splitting parameters, suggest the presence of a trench‐parallel sub‐slab flow system driven by slab rollback, a trench‐perpendicular corner flow, and a trench‐parallel flow possibly entering the mantle wedge through a slab window or gap.