近日，美国地质调查局Thelen Weston A.及其团队报道了喀斯喀特山脉火山下长期的部分融化。这一研究成果于2025年1月23日发表在国际顶尖学术期刊《自然—地球科学》上。

据介绍，岩浆储量的定量估计是评价火山动力学和危险性的基础。然而，人们对次火山岩浆管道系统及其可变性的了解仍然有限。关于浅层岩浆储存的短暂性及其相对于喷发量的体积，以及上火山口岩浆体是否可能是即将喷发的标志，一直存在争论。

本文通过系统模拟远震体波的三维散射波场，展示了沿喀斯喀特山脉弧的次火山岩浆系统的地震成像。这揭示了低地震速度体的令人信服的证据，表明在大多数喀斯喀特山脉火山下方5至15公里深度之间存在部分融化。

这些火山下的岩浆储层在深度、大小和复杂程度上各不相同，但无论喷发通量如何，也无论自伴生火山上次喷发以来的时间如何，上火山口岩浆体都很普遍。这表明，在大型火山的喷发周期中，大量的熔体可以在浅层深处持续存在。

附：英文原文

Title: Long-lived partial melt beneath Cascade Range volcanoes

Author: Pang, Guanning, Abers, Geoffrey A., Moran, Seth C., Thelen, Weston A.

Issue&Volume: 2025-01-23

Abstract: Quantitative estimates of magma storage are fundamental to evaluating volcanic dynamics and hazards. Yet our understanding of subvolcanic magmatic plumbing systems and their variability remains limited. There is ongoing debate regarding the ephemerality of shallow magma storage and its volume relative to eruptive output, and so whether an upper-crustal magma body could be a sign of imminent eruption. Here we present seismic imaging of subvolcanic magmatic systems along the Cascade Range arc from systematically modelling the three-dimensional scattered wavefield of teleseismic body waves. This reveals compelling evidence of low-seismic-velocity bodies indicative of partial melt between 5 and 15km depth beneath most Cascade Range volcanoes. The magma reservoirs beneath these volcanoes vary in depth, size and complexity, but upper-crustal magma bodies are widespread, irrespective of the eruptive flux or time since the last eruption of the associated volcano. This indicates that large volumes of melts can persist at shallow depth throughout eruption cycles beneath large volcanoes.

DOI: 10.1038/s41561-024-01630-y

Source: https://www.nature.com/articles/s41561-024-01630-y