Pn Velocity Structure and Anisotropy of the Uppermost Mantle Beneath Myanmar

Abstract 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.