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Myanmar is surrounded by complex seismotectonic elements and threatened by a high seismic risk. The Central yanmar Basin (CMB) hosts the largest and fastest growing cities of Myanmar. The CMB is bounded by the Indo- Myanmar subduction zone to the west and the Sagaing fault to the east and is a seismically active tectonic block that has experienced large earthquakes (up to magnitude 8.0). A large earthquake in this region would affect Yangon and its surrounding population of around 8 million. Sedimentary basins have a significant contribution to seismic wave propagation, amplification and duration of ground shaking. Thus, to more accurately estimate the seismic hazard, a clear understanding of the detailed basin structures is required. The goal of our study is to map crustal structures, i.e. crustal thickness, crustal blocks, basin shape, size and depth, fault geometry, dipping layers and intra-crustal layers beneath the Yangon region. We will present receiver functions from a dense array of 168 nodal seismometers with the goal of revealing high-resolution seismic images of the basin. Our dense array will improve basin imaging by reducing uncertainties in receiver function interpretations. Developing a better understanding of basin structures will help our understanding of seismic amplification in the basin and thus will help to more accurately estimate the seismic hazard of this region. 

Abstract 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.