Deep Geophysical Anomalies Beneath the Changbaishan Volcano

Abstract

Subsurface imaging is key to understanding the origin of intraplate volcanoes. The Changbaishan volcano, located about 2,000 km away from the western Pacific subduction zone, has several debated origins. To investigate this, we compared regional seismic tomography with the electrical resistivity results and obtained high‐resolution 1D and quasi‐2D velocity‐depth profiles. We show that the upper mantle is characterized by two anomalies exhibiting distinct features which cannot be explained by the same mechanism. We document a localized low‐velocity anomaly atop the 410‐km discontinuity, where the P‐wave velocity is reduced more than that of the S‐wave (i.e., lower Vp/Vs). We propose that this anomaly is caused by the reduction of the effective moduli during the phase transformation of olivine. The other anomaly, located between 300 and 370 km depth, reveals a significant reduction of the S‐wave velocity (i.e., higher Vp/Vs), associated with a reduction of the electrical resistivity, altogether consistent with partial melting.

Control of slab tears and slab flat wedging on volcanism in the Alaska subduction zone

“…8a). This type of slab tearing was not limited to the Aleutian arc but has also been observed in other regions of the Paci c Plate, such as the Wrangell Volcanic eld 27,53 and northeast China 54 . Therefore, the combination of partial melting of subducting oceanic crust, mantle wedge melting induced by plate dehydration, and upwelling of asthenosphere materials through a torn slab collectively contributed crucial magma for volcanic activities within the Aleutian volcanic chain.…”

Seismicity and Magmatic System of the Changbaishan Intraplate Volcano in East Asia

“…In contrast, V s is mostly affected by the fluid phase or partial melts. Therefore, a large amount of partial melts and high‐temperature zones in the magma chamber would significantly influence the shear strength of surrounding rocks but affect the compressive strength modestly due to the hydration of crystal lattices or grain boundaries (Kasatkina et al., 2014; Koulakov et al., 2021; Li et al., 2023; Toomey et al., 1998). In addition, the high‐ V p anomaly might indicate that the magma chamber has been partially crystallized, which is similar to a high‐velocity layer revealed beneath the Datong volcano (He et al., 2021).…”