Investigating cyclic changes in the potential field at Soufrière Hills volcano, Montserrat

研究蒙特塞拉特苏弗里埃尔山火山势场的周期性变化

• 批准号: NE/E007961/1
• 负责人: Joachim Gottsmann
• 金额: $ 2.6万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FE007961%2F1
• 关键词: Investigating; cyclic; changes; potential; field

Volcanic eruptions are among the most spectacular events of the natural world, but pose a threat to lives and property of millions of people. Eruptions are the effect of complex sub-surface processes, which lead to quantifiable signals recorded by geophysical monitoring. Processes such as magma migration, tectonic and hydrothermal activity can trigger seismicity, ground deformation, thermal variations and changes in the magnetic and gravity fields around a volcano. Very often volcanic activity follows cyclic patterns, revealed by the geophysical record. The challenge for volcano scientists lies in deciphering causes for the geophysical signals and for their cyclic behaviour. Usually, signals at an erupting volcano are almost exclusively attributed to magmatic processes. However, there is a growing awareness that shallow processes in hydrological reservoirs (e.g., ground water flow and recharge) and hydrothermal reservoirs (e.g., steam/liquid interface propagation) have an important influence on and induce geophysical signals recorded at the ground surface. Based on cyclic data obtained by the PI during a reconnaissance study, this project aims to tackle this challenge via a novel multi-parametric investigation of geophysical signals at the active Soufrière Hills volcano, Montserrat (B.W.I). The project proposes to investigate the sub-surface system at the volcano via a combination of continuous ground deformation and continuous potential field (gravimetric and electromagnetic) studies. Global Positioning Satellite Systems (GPS) can quantify ground deformation caused by volume changes beneath a volcano to sub-centimetre precision. Gravimeters are capable of resolving minute changes (1 in 10^8) in the Earth's gravitational field due to mass emplacement or density changes at depth. Very low frequency electromagnetic measurements record electrical conductivity contrasts during physico-chemical changes in the ground at less than 500 m depth. The combination of the three techniques enables the direct quantification of shallow processes and their influence on other geophysical signal recorded in the existing monitoring network at the volcano. Combining the techniques enables the quantification of volume and mass changes over time, from which to infer the density of the causative source at shallow depth. Hydrothermal fluids have densities similar or lower than that of tap water. Magma erupted at the volcano is by at least a factor of two denser. The project aims to i) quantify short-term cyclic activity particularly related to shallow sub-surface processes at the SHV via continuous potential field and ground deformation measurements, ii) develop conceptual physical models of shallow processes, iii) separate contributions from hydrological and hydrothermal processes to the recorded signals and to obtain a fundamental understanding of their dynamics, iv) to correlate shallow signals with eruption signals to explore the mutual interaction of deep and shallow processes at an erupting volcano, v) devise strategies for integrating potential field measurements into existing monitoring programs at SHV and vi) to provide a first quantification of hydrothermal dynamics with respect to the prospect of geothermal exploitation in the south of Montserrat. Results will be validated and interpreted together with data from supplementary geophysical and geochemical investigations performed by staff of the Montserrat volcano observatory to identify and separate dynamics pertaining to (shallow) hydrothermal and (deep) magmatic activity for improved forecasting volcanic activity

火山爆发是自然界最壮观的事件之一，但对数百万人的生命和财产构成威胁。火山爆发是复杂的地下过程的结果，导致地球物理监测记录到可量化的信号。岩浆迁移、构造和热液活动等过程可触发地震活动、地面变形、热变化以及火山周围磁场和重力场的变化。火山活动经常遵循地球物理记录所揭示的周期性模式。火山科学家面临的挑战在于破译地球物理信号及其循环行为的原因。通常，火山爆发的信号几乎完全归因于岩浆过程。然而，人们越来越认识到，水文水库中的浅层过程（例如，地下水流和补给）和热液储层（例如，蒸汽/液体界面传播）对在地面记录的地球物理信号具有重要影响并引起地球物理信号。根据PI在勘测研究期间获得的周期数据，该项目旨在通过对蒙特塞拉特（B.W.I）苏弗里耶尔山活火山的地球物理信号进行新颖的多参数调查来应对这一挑战。该项目拟通过连续地面变形和连续势场（重力和电磁）研究相结合的方式调查火山的地下系统。全球定位卫星系统（GPS）可以量化火山下体积变化造成的地面变形，精确到厘米以下。重力仪能够分辨出由于质量的就位或深度的密度变化而引起的地球重力场的微小变化（1/10^8）。甚低频电磁测量记录了在不到500米深度的地下物理化学变化期间的电导率对比。这三种技术相结合，使浅层过程及其对其他地球物理信号的影响，在现有的火山监测网络记录的直接量化。将这些技术结合起来，可以量化体积和质量随时间的变化，从而推断出浅深度处成因源的密度。热液流体的密度与自来水的密度相似或更低。火山喷发的岩浆密度至少是原来的两倍。该项目的目的是：i）通过连续势场和地面变形测量，量化短期周期活动，特别是与SHV浅层地下过程有关的活动，ii）开发浅层过程的概念物理模型，iii）区分水文和热液过程对记录信号的贡献，并对其动态有基本的了解，iv）将浅层信号与喷发信号相关联，以探索喷发火山处的深层和浅层过程的相互作用，v）设计将潜在场测量纳入SHV现有监测计划的策略，以及vi）对蒙特塞拉特南部地热开发的前景提供热液动态的第一个量化数据。结果将与蒙特塞拉特火山观测站工作人员进行的补充地球物理和地球化学调查的数据一起进行验证和解释，以查明和区分与（浅层）热液和（深层）岩浆活动有关的动态，从而更好地预测火山活动

项目成果

Modelling ground deformation caused by oscillating overpressure in a dyke conduit at Soufrière Hills Volcano, Montserrat

模拟蒙特塞拉特苏弗里埃尔山火山堤坝管道中振荡超压引起的地面变形

• DOI: 10.1016/j.tecto.2008.10.021
• 发表时间: 2009
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: Hautmann S

The Transcrustal Magma Reservoir Beneath Soufrière Hills Volcano, Montserrat: Insights From 3-D Geodetic Inversions

蒙特塞拉特苏弗里埃尔山火山下的跨地壳岩浆储层：来自 3-D 大地测量反演的见解

• DOI: 10.1029/2020gl089239
• 发表时间: 2020
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Gottsmann J

4D volcano gravimetry

• DOI: 10.1190/1.2977792
• 发表时间: 2008-11-01
• 期刊: GEOPHYSICS
• 影响因子: 3.3
• 作者: Battaglia, Maurizio;Gottsmann, Joachim;Fernandez, Jose
• 通讯作者: Fernandez, Jose

Groundwater recharge and flow on Montserrat, West Indies: Insights from groundwater dating

西印度群岛蒙特塞拉特岛的地下水补给和流量：地下水测年的见解

• DOI: 10.1016/j.ejrh.2015.08.003
• 发表时间: 2015
• 期刊: Regional Studies
• 影响因子: 4.6
• 作者: Hemmings B

The shallow structure beneath Montserrat (West Indies) from new Bouguer gravity data

来自新布格重力数据的蒙特塞拉特岛（西印度群岛）下方的浅层结构

• DOI: 10.1002/grl.51003
• 发表时间: 2013
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Hautmann S