The crustal magma reservoir geometry and seismic activity beneath the Wudalianchi volcano in northeast China: Implications for the multilevel magmatic system

Abstract. Understanding the spatial correlation between crustal magma reservoir and seismicity is crucial for investigating the dynamics of volcanic systems. However, due to the relatively low resolution of existing crustal tomography, especially for the middle-lower crustal magma reservoir, it is still difficult to accurately characterize the crustal magma system beneath the Wudalianchi volcano in northeast China. Here, we present a high-resolution 3-D shear-wave velocity crustal model obtained by applying full-wave ambient noise tomography. High-quality empirical Green's functions are extracted from ambient seismic noise at periods of 3–20 s based on 30 latest broadband seismic stations throughout the Wudalianchi volcano. Our new tomographic model reveals a distinct low-velocity body located at depths of ~10–23 km below the Wudalianchi volcano, suggesting the presence of a magma reservoir in the middle-lower crust, which establishes an important link for better understanding of the magma evolution processes. Additionally, the geometry of observed magma reservoir, together with the earthquake distribution, provides new insights into the magmatic activity of the active Wudalianchi volcano. The magma ascent from the potential middle-lower crustal magma reservoir might exert pressure on the overlying brittle crust, resulting in the generation of the earthquakes below the Wudalianchi volcano. The presence of partial melting could make the strength of the surrounding rocks more susceptible to ductile deformation, suggesting that the earthquake nucleation is more difficult within the interior of the crustal magma reservoir beneath the WDLC volcano.