Systematic mapping of magma bodies under Cascades volcanoes

喀斯喀特火山下岩浆体的系统制图

• 批准号: 2313452
• 负责人: Geoffrey Abers
• 金额: $ 43.32万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2313452&HistoricalAwards=false
• 关键词: Systematic; mapping; magma; bodies; under

Volcanic eruptions threaten public safety and can cause severe social and economic damage. Most eruptions of continental arc volcanoes are supplied from molten rock, or magma, that builds up in a reservoir somewhere in the crust. However, the size, distribution and depth of crustal magma systems, and their variability between volcanoes, remain poorly known beneath most active systems. The aim of the project is to quantify this variability by providing a synoptic, holistic seismic imaging survey of magma systems along one arc, the Cascades arc of Washington, Oregon and northern California. This arc poses the largest threat to population centers of any in the United States. The study leverages abundant newly deployed or upgraded seismographs placed within a few kilometers of the summits of many of the high-threat Cascades volcanoes, operated by the U.S. Geological Survey. These instruments for the first time provide seismic signals at a scale that could pass through the magma reservoirs. The signals will allow for the first uniform sampling of the magma systems beneath most major Cascades volcanoes. The project supports a postdoc and a graduate student at Cornell University, who will collaborate with scientists at the U.S. Geological Survey’s Cascades Volcano Observatory (CVO). The project will help CVO set up a workflow for continuously monitoring volcanic activities. The project will take advantage of the upgraded seismic monitoring network of CVO and apply several robust seismic techniques to image key volcanic centers along the Cascades volcano arc systematically. Receiver functions frequently show large-amplitude signals near volcanoes that are not seen elsewhere. They will be derived for all near-summit stations, and used to identify and describe sharp interfaces, particularly the tops of magma bodies that produce distinctive seismic velocity inversions. Ambient-noise imaging will be conducted to measure absolute S-wave velocities in the regions sampled by receiver functions, to constrain critical physical properties. These and other measurements are complemented by a comprehensive suite of full-waveform forward models to understand better how finite-wavelength signals interact with magma bodies. These measurements will be jointly inverted and interpreted in a context of variable geometry melt-wavespeed relationships. The ambient noise analyses will also serve as a baseline in a search for temporal changes in seismic wavespeeds near volcanoes, a potential indication of magma movements. The work, for the first time, provides robust, consistent images of magma plumbing systems at multiple volcanoes and will provide more systematic assessments of magma reservoir characteristics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

火山喷发威胁着公共安全，并可能造成严重的社会和经济损害。连续弧火山的大多数爆发都是由熔融岩石或岩浆提供的，这些岩石在地壳的某个地方的水库中积聚。但是，在大多数活性系统下，地壳岩浆系统的大小，分布和深度及其在火山之间的变化仍然很差。该项目的目的是通过对沿一个弧线，华盛顿，俄勒冈州和北加州的层弧形的岩浆系统进行概要的整体地震成像调查来量化这种可变性。该弧对美国任何人的人口中心构成了最大的威胁。该研究利用了由美国地质调查局运营的许多高威胁性喀斯喀特火山的山顶几公里的新部署或升级的地震仪。这些仪器首次提供了可以通过岩浆储层的规模的地震信号。这些信号将允许在大多数主要级联火山下的岩浆系统进行第一次均匀采样。该项目支持康奈尔大学的博士后和研究生，他将与美国地质调查局的喀斯喀特火山天文台（CVO）的科学家合作。该项目将帮助CVO设置一个工作流程，以进行连续监测火山活动。项目将利用CVO的升级地震监测网络，并采用多种强大的地震技术来系统地沿喀斯喀特火山弧沿着关键的火山中心进行成像。接收器的功能经常显示在其他地方没有看到的火山附近的大振幅信号。它们将用于所有近距离的站点，并用于识别和描述尖锐的界面，尤其是产生独特的地震速度反演的岩浆体的顶部。将进行环境噪声成像，以测量接收器功能采样区域中的绝对S波速度，以限制关键物理性质。这些测量和其他测量由全面的全波向前模型套件完成，以更好地了解有限波长信号如何与岩浆体相互作用。这些测量结果将在可变的几何融化波关系的背景下共同倒置和解释。环境噪声分析也将作为寻找火山附近地震波动的暂时变化的基线，这是岩浆运动的潜在指示。这项工作首次为多个火山提供了岩浆管道系统的强大，一致的图像，并将提供对岩浆储层特征的更系统评估。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准来通过评估而被认为是珍贵的支持。