Ambient Noise Imaging of the Magma System Beneath the Changbaishan Volcanic Field

To address long-standing debates regarding the spatial distribution, geometry, and depth range of the crustal magmatic system beneath the Changbaishan volcanic field, particularly the sparse geophysical constraints for the Wangtian’e and Namphothe volcanoes, we systematically integrated continuous waveform data from a dense network of 237 regional seismic stations, including permanent stations and multiple portable arrays. Using both ambient noise two-station cross-correlation (C2) and three-station interferometry (C3), we extracted Rayleigh-wave phase-velocity dispersion measurements with significantly denser ray-path coverage across the study area. We then constructed a high-resolution 3-D S-wave velocity model by directly inverting the dispersion data. Our results revealed pronounced mid-to-upper crustal velocity heterogeneities beneath different volcanic centers. Beneath the Tianchi volcano, distinct low-velocity anomalies are imaged with varying amplitudes: a strong low-velocity anomaly at 0–6 km depth and a weaker one at 6–14 km depth, likely corresponding to shallow hydrothermal activity and an underlying magma chamber, respectively. In contrast, the mid-to-upper crust beneath the Wangtian’e and Namphothe volcanoes is dominated by high-velocity anomalies. At greater depths, low-velocity anomalies appear broadly connected, suggesting that volcanoes along the Changbaishan volcanic belt may share a common deep magmatic source.