Observing conduit flow processes during Strombolian Eruptions using Transient Electromagnetics (TEM): a numerical and field approach

使用瞬态电磁学 (TEM) 观察斯特龙博利火山喷发期间的管道流动过程：数值和现场方法

• 批准号: 434373481
• 负责人: Professor Dr. Matthias Hort
• 金额: --
• 依托单位: Institut für Geophysik (IfG)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/434373481?language=en
• 关键词: Observing; conduit; flow; processes; during

Volcanic eruptions are one of the most fascinating spectacles that can be witnessed on Earth. They are boon and bane to mankind and mitigating the effects of volcanic eruptions is a major societal task. Among other things mitigation strategies involve short term crisis management including short notice eruption warnings. Most crucial in this regard is the understanding of processes inside volcanic conduits preceding an eruption. In situ observations of magma transport processes in the conduit are still nearly impossible. So far almost all measurements rely on remote sensing techniques like seismological observations, tilt measurements or ground based InSAR observations. All processes in the conduit prior to an eruption involve the nucleation and growth of bubbles. In case of strombolian eruptions these bubbles are usually quite elongated with a length to width ratio being much larger than 1. They are called gas slugs. One of the goals of this proposal is to explore the potential of transient electromagnetics (TEM) to monitor the final rise of such gas slugs in the volcanic conduit passing through the last 100 m prior to the eruptions. Electromagnetic methods in general show a high potential in volcanic environments due to inductive coupling and the high conductivity contrast between magma, gas and host rock. By running virtual experiments using a highly sophisticated three-dimensional TEM forward simulation software we will explore the sensitivity of the subsurface response taking especially into account real topography and subsurface features like hydrothermal systems as well as a magma filled conduit including a gas slug. We will investigate the effect of various setups including different source/receiver configurations on the TEM response in a realistic volcanic setting. This will allow us to determine characteristic signals that we would expect to record at an active volcano using TEM prior to an eruption. In order to do so, we will expand an existing software with an adaptive meshing and sophisticated geomodeling tools to properly describe the volcanic edifice leading to novel modeling techniques and results in geoelectromagnetics.Applying a detailed sensitivity study using geophysical information available for Stromboli volcano, Italy, we will carry out a set of virtual experiments to constrain possible measurement configurations to optimize a field experiment at Stromboli. We propose to carry out a field experiment using TEM for monitoring processes within the volcanic conduit. These TEM measurements will be complemented by monitoring the eruptions using cameras and Doppler radar. Combining those data hopefully enables us to better constrain slug rise and benchmark numerical models for the rise of gas slugs in volcanic conduits thereby improving volcanic hazard mitigation.

火山喷发是地球上最迷人的奇观之一。它们对人类来说是福是祸，减轻火山喷发的影响是一项重大的社会任务。除其他外，缓解策略还涉及短期危机管理，包括临时通知的喷发警告。在这方面最重要的是了解火山喷发前火山管道内的过程。对管道中岩浆输送过程进行现场观测仍然几乎是不可能的。到目前为止，几乎所有测量都依赖于遥感技术，如地震观测、倾斜测量或地面 InSAR 观测。喷发前导管中的所有过程都涉及气泡的成核和生长。在斯特龙博利式喷发的情况下，这些气泡通常会相当拉长，长宽比远大于 1。它们被称为气段塞。该提案的目标之一是探索瞬态电磁学 (TEM) 的潜力，以监测火山喷发前经过最后 100 m 的火山管道中此类气体段塞的最终上升。由于感应耦合以及岩浆、气体和主岩之间的高电导率对比，电磁方法通常在火山环境中显示出很高的潜力。通过使用高度复杂的三维 TEM 正向模拟软件运行虚拟实验，我们将探索地下响应的敏感性，特别考虑到真实的地形和地下特征，如热液系统以及包括气段塞在内的岩浆填充管道。我们将研究各种设置（包括不同源/接收器配置）对真实火山环境中 TEM 响应的影响。这将使我们能够在活火山喷发前使用 TEM 确定我们期望记录的特征信号。为此，我们将使用自适应网格划分和复杂的地理建模工具来扩展现有软件，以正确描述火山大厦，从而带来新颖的建模技术和地电磁学结果。利用意大利斯特龙博利火山的地球物理信息进行详细的敏感性研究，我们将进行一组虚拟实验，以限制可能的测量配置，以优化现场 在斯特龙博利进行实验。我们建议使用 TEM 进行现场实验来监测火山管道内的过程。这些 TEM 测量将通过使用摄像机和多普勒雷达监测喷发来补充。结合这些数据有望使我们能够更好地限制段塞上升并为火山管道中段塞上升的数值模型建立基准，从而改善火山灾害缓解。