利用接收函数方法探测长白山火山区地壳结构及其流变特征OA

In recent years,the potential eruption hazard of Changbaishan Tianchi volcano has attracted increasing attention from geoscientific researchers worldwide.However,the magma plumbing system beneath the Tianchi volcanic area remains inadequately understood.This study aims to characterize the crustal structure and magmatic activity beneath the Changbaishan volcanic region in detail.We analyze data from a high-density seismic array deployed in 2023 around the Tianchi and Wangtian'e volcanoes and their surrounding areas,using receiver-function H-κ stacking to obtain high-resolution images of crustal thickness and Vp/Vs ratios.The results show that in regions distant from volcanic centers,the crust is approximately 35 km thick with an average Vp/Vs ratio of～1.76.Beneath the Tianchi caldera,the crust is significantly thickened(>39 km)and exhibits markedly elevated Vp/Vs ratios(>1.93),suggesting the presence of partial melting.In contrast,although the crust beneath Wangtian'e volcano does not display significant thickening(～34 km),it is also characterized by high Vp/Vs ratios exceeding 1.90.Based on empirical relationships,we estimate partial melting of approximately 3-5%beneath both the Tianchi and Wangtian'e volcanoes.These observations suggest that mantle-derived melts beneath the Changbaishan volcanic region initially accumulate near the Moho beneath Tianchi,contributing to localized crustal thickening.Subsequently,melt within the lower crust migrates laterally,supplying independent magma reservoirs beneath both Tianchi and Wangtian'e volcanoes.Our findings indicate that the long-considered"extinct"Wangtian'e volcano still hosts an active magmatic system,highlighting the need to reassess volcanic activity across the Changbaishan volcanic field and to implement more comprehensive volcanic monitoring.This study provides important constraints on the interconnected evolution of magmatic systems in the region.