Seismic structures around the Mt.Baekdu (Changbaishan) intraplate volcano by Bayesian joint inversion of receiver functions and surface wave dispersions

Magmatic lithospheric structures beneath Mt.Baekdu are still enigmatic and important to estimate the magma conduit and current status of the volcano. In a previous study using surface wave dispersions of ambient noise data (Kim et al., 2017) suggested that the thick crust with high velocities shallow layer extends to about 100 km to the north from Mt.Baekdu. Here, we test previously defined structures about the existence of cooled layers in the crust and check whether there are still partial melting throughout the summit. We combine data from three temporary seismic arrays distributed around the volcano and the border between Northeast China and DPRK. To obtain isotropic-assumed P-receiver functions and estimate the degree of anisotropy, a harmonic decomposition analysis is applied. Then a hierarchical transdimensional Bayesian joint inversion is conducted with the surface wave dispersion data and isotropic receiver functions to extract shear-wave velocity structure models. Inverted structural models show a consistent pattern that the unclear and deeper Moho discontinuity (up-to 45 km) beneath Mt.Baekdu contrasts to other regions with the relatively sharp and shallow Moho (33-35 km). However, average velocities do not differ from each other with ranges of 3.5-3.7 km/s in the crust and 4.3-4.4 km/s in the upper mantle. These results indicate that the crust beneath the volcano has no particularly elevated crustal temperature, but more modified crustal structures with thickened crust by possibly magma underplating.