Collaborative Research: An integrated seismic-geodetic study of active magmatic processes at Sierra Negra volcano, Galapagos Islands

合作研究：加拉帕戈斯群岛塞拉内格拉火山活动岩浆过程的综合地震大地测量研究

• 批准号: 0838461
• 负责人: Dennis Geist
• 金额: $ 7.5万
• 依托单位: Regents of the University of Idaho
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-15 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838461&HistoricalAwards=false
• 关键词: Collaborative; Research; integrated; seismic; geodetic

Intellectual MeritsOcean island volcanoes initiate and grow over time periods of 105 to 106 years, requiring a long-lived magmatic plumbing system to transport magma from the mantle to the surface. Only a fraction of the magma, however, is erupted; magma is stored in crustal magma chambers, or trapped near the crust-mantle boundary. These magma intrusions grow the crust, and change the state of stress. The increase in pressure accompanying magma intrusion inflates the volcanic edifice, triggering earthquakes and eruptions. The geometry of the magma chambers and conduits, therefore, is fundamental to the development of predictive models of volcano deformation and eruption.Our integrated seismic and geodetic data acquisition and modelling project aims to image the magma plumbing system beneath the most rapidly deforming hotspot volcano system in the world: Sierra Negra volcano in the Galapagos Archipelago. Existing SAR data provide high-resolution images of surface deformation over broad regions, and GPS provides continuous time series of vertical and horizontal deformation. We cannot, however, differentiate between the basaltic volcano growth models without complementary seismic information on the distribution and mechanisms of seismic strain, as well as the crust and upper mantle structure. We will deploy and maintain 16 broadband seismometers for two years, recording seismic waves from local and distant earthquakes to illuminate the magmatic plumbing system and state of stress within the lithosphere beneath Sierra Negra volcano to understand the stress interaction between shallow magma intrusion, extrusion, and intra-caldera faulting processes. The anticipated results are a new 4D model of Sierra Negra?s shallow and deep magmatic system that satisfies seismic and geodetic observations, and is constrained by earthquake locations, focal mechanisms, wavespeed and ambient noise tomography, seismic anisotropy, receiver function estimates of sill and Moho depths, and existing petrological data. We will determine the time-varying state of stress within and around the volcano in response to magma intrusion and withdrawal, including the dynamic relationship between trapdoor faulting and magma intrusionBroader Significance and ImportanceOcean island volcanoes initiate and grow over time periods of 105 to 106 years, requiring a long-lived magmatic plumbing system to transport magma from the mantle to the surface. Only a fraction of the magma, however, is erupted; magma is stored in crustal magma chambers, or trapped near the crust-mantle boundary. These magma intrusions grow the crust, and change the state of stress. The increase in pressure accompanying magma intrusion inflates the volcanic edifice, triggering earthquakes and eruptions. Sierra Negra volcano in the Galapagos Archipelago is the most rapidly deforming of these ocean island volcanoes. Continuous monitoring of earthquake and surface deformation is vital to deduce the geometry of the magma chambers and conduits, and the physical changes to the volcano edifice itself. These data, in turn, inform predictive models of volcano deformation and eruption worldwide.Our continuous seismic, satellite, GPS monitoring and modeling project has been designed to maximize the broader impacts, which fall into 3 areas: volcanic hazards, education, and international collaboration. Nearly a million people live on active basaltic volcanoes; understanding the relationship between magma supply, state of stress and eruptions is vital for hazard assessment, including the potential for tsunami-generating flank instabilities. The baseline provided by the geodetic and seismic monitoring is essential to development of a volcanic hazard mitigation program in the Galápagos Archipelago, and other basaltic volcanoes worldwide.This project will provide a collaborative opportunity for US undergraduate, graduate, and Ecuadorian students. Students from both countries will benefit from experience with the realities of field-based geophysics, gaining valuable skills in seismology and geodesy that can be translated to the workplace or advanced degree programs.This work is co-funded by the Geophysics and Geochemistry Programs and the Americas Program of the Office of International Science and Engineering.

海洋岛屿火山的形成和发展需要105至106年的时间，需要一个长期存在的岩浆管道系统将岩浆从地幔输送到地表。 然而，只有一小部分岩浆被喷发出来;岩浆被储存在地壳岩浆房中，或者被困在壳幔边界附近。 这些岩浆侵入使地壳生长，并改变了应力状态。伴随着岩浆侵入的压力增加使火山建筑物膨胀，引发地震和火山爆发。因此，岩浆房和管道的几何形状是火山变形和喷发预测模型的基础。我们的综合地震和大地测量数据采集和建模项目旨在对世界上变形最快的热点火山系统下的岩浆管道系统进行成像：加拉帕戈斯群岛的Sierra Negra火山。现有的合成孔径雷达数据提供了大面积地表变形的高分辨率图像，全球定位系统提供了垂直和水平变形的连续时间序列。然而，如果没有关于地震应变分布和机制以及地壳和上地幔结构的补充地震信息，我们就无法区分玄武岩火山生长模型。我们将部署和维护16个宽带地震仪两年，记录来自本地和远程地震的地震波，以阐明Sierra Negra火山下岩石圈内的岩浆管道系统和应力状态，以了解浅岩浆侵入，挤出和火山口内断层过程之间的应力相互作用。 预期的结果是一个新的4D模型的塞拉内格拉？的浅层和深层岩浆系统，满足地震和大地测量观测，并受到地震位置，震源机制，波速和环境噪声层析成像，地震各向异性，接收函数估计的窗台和莫霍面深度，和现有的岩石学数据。我们将确定火山内部和周围的应力随时间变化的状态，以应对岩浆的侵入和退出，包括活板门断层和岩浆intrusionBroader意义和ImportanceOcean岛屿火山的启动和增长超过105至106年的时间周期之间的动态关系，需要一个长寿的岩浆管道系统从地幔到表面运输岩浆。 然而，只有一小部分岩浆被喷发出来;岩浆被储存在地壳岩浆房中，或者被困在壳幔边界附近。 这些岩浆侵入使地壳生长，并改变了应力状态。伴随着岩浆侵入的压力增加使火山建筑物膨胀，引发地震和火山爆发。 位于加拉帕戈斯群岛的塞拉内格拉火山是这些海洋岛屿火山中变形最快的。 对地震和地表变形的连续监测对于推断岩浆房和管道的几何形状以及火山建筑物本身的物理变化至关重要。 这些数据反过来又为全球火山变形和喷发的预测模型提供信息。我们的连续地震、卫星、GPS监测和建模项目旨在最大限度地扩大更广泛的影响，这些影响分为3个领域：火山灾害、教育和国际合作。 近100万人生活在活跃的玄武岩火山上;了解岩浆供应、应力状态和喷发之间的关系对于灾害评估至关重要，包括潜在的海啸生成侧翼不稳定性。由大地测量和地震监测提供的基线对于加拉帕戈斯群岛和世界各地其他玄武岩火山的火山灾害缓解计划的发展至关重要。该项目将为美国本科生，研究生和厄瓜多尔学生提供合作机会。来自这两个国家的学生将受益于基于场的地球物理学的现实经验，获得地震学和大地测量学的宝贵技能，这些技能可以转化为工作场所或高级学位课程。这项工作由地球物理学和地球化学项目以及国际科学与工程办公室的美洲项目共同资助。