Crustal and Upper Mantle Structure of the Thailand–Myanmar–Malaysia Region Revealed by Rayleigh Wave Phase Velocity Using Ambient Seismic Noise

The Thailand–Myanmar–Malaysia region is characterized by a complex tectonic setting and significant seismic hazard, necessitating a detailed understanding of its crustal and upper mantle structure. This study addresses knowledge gaps in the region’s deep lithospheric structure, aiming to elucidate its tectonic evolution and geodynamics. We present high‐resolution Rayleigh wave phase velocity maps for the region, derived from ambient noise tomography using continuous seismic data from a dense network of 99 broadband stations. Through the analysis of empirical Green’s functions at periods of 10–100 s, we investigate structures ranging from the middle crust to the upper mantle. The phase velocity maps at periods reveal distinct velocity variations that correlate with major tectonic features, such as the Sagaing Fault, the Shan‐Thai Terrane, and the Khorat Plateau. Low‐velocity anomalies are observed in the West Burma Terrane and the Khorat Plateau, while high‐velocity anomalies characterize the Shan‐Thai Terrane, Peninsular Thailand, and Peninsular Malaysia. At shorter periods (10–15 s), we observe a clear demarcation between high velocities in the Shan‐Thai Terrane and low velocities in the Indo‐China Terrane, reflecting significant differences in shallow crustal structure and composition. At longer periods, the phase velocity maps provide evidence for a cold, stable lithospheric mantle beneath the Shan‐Thai Terrane and Peninsular Malaysia, and thin, hot lithosphere or upwelling asthenosphere beneath central Myanmar and the Gulf of Thailand. These findings offer new insights into the region’s crustal composition, thickness, and tectonic boundaries, contributing to our understanding of Southeast Asia’s complex geodynamics and tectonic structure.