Imaging the Upper 10 km Crustal Shear‐Wave Velocity Structure of Central Myanmar via a Joint Inversion of P‐Wave Polarizations and Receiver Functions


Myanmar occupies a complex region in the active Indo‐Burma subduction system. To illuminate the upper 10 km crustal structure of central Myanmar and obtain new insight into the subduction system, we jointly use P‐wave polarizations and receiver functions (RFs) to construct a high‐resolution VS profile based on a Bayesian Markov chain Monte Carlo approach. This obtained profile clearly delineates six tectonic units and their boundaries, including the Indo‐Burman ranges (IBR), the IBR‐fore‐arc basin boundary, the fore‐arc basin, the volcanic arc, the back‐arc basin, and the Sunda plate. The Sunda plate has relatively higher upper crustal VS (>3.0 km/s) and thinner sedimentary cover (∼1 km) compared with the Central Myanmar basin in the Burma plate. The fore‐arc basin, containing thick sediments (>10 km), and the back‐arc basin, with thinner sediments (∼1–6 km), are separated by a region with higher VS (∼3.0 km/s), which represents crystallized magma beneath the volcanic arc. A narrow zone of relatively high‐VS (∼2.6–2.7 km/s) ophiolites is situated between the fore‐arc basin and the IBR. We also find a narrow zone of high‐VS (∼2.9 km/s) metamorphic rocks contained within the low‐VS (⁠≲2.3 km/s) IBR. This study suggests that the proposing joint inversion of two types of single‐station measurements, that is, P‐wave polarizations and RFs, can robustly and computationally efficiently image the shallow VS structure and provide a reliable uncertainty estimation.

Seismological Research Letters