Collaborative Research: Seismic Waves from Volcanoes: Fully Coupled Time-Dependent Models of Fluid Flow Through Elastic Walled Conduits

合作研究：火山地震波：通过弹性壁管道的流体流动的完全耦合时变模型

• 批准号: 1114073
• 负责人: Eric Dunham
• 金额: $ 22.47万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1114073&HistoricalAwards=false
• 关键词: Collaborative; Research; Seismic; Waves; Volcanoes

Mitigating the risks associated with volcanoes requires a detailed understanding of the transport and eruption of magma through cracks and conduits in Earth's crust. Seismic waves excited by magma flow and its coupling to the elastic wall rocks can be used to place valuable constraints on parts of the volcanic system that are otherwise inaccessible. The complexity of observed seismic signals and the difficulty of modeling the coupled fluid-solid system present a formidable challenge. The objective of this collaborative proposal is to develop numerical models describing the high-speed flow of compressible, viscous fluids through narrow channels in elastic bodies, together with the propagation of seismic waves through the solid. The fluid and solid response is fully coupled: elastic deformation changes the cross-sectional area of the conduit through which fluid flows, and changes in fluid pressure push the conduit walls in and out, exciting seismic waves.Specifically, the project group will develop a provably stable and accurate numerical method for time-dependent quasi-one-dimensional fluid flow through conduits in a solid body, together with the elastodynamic response of that solid. The model will include changes in compressibility, sound speed, viscosity, and drag from gas exsolution. The code will be used first to explore the role of conduit wall deformation on steady state eruption dynamics. The group will then assess the stability of steady state eruption solutions. Preliminary analyses indicate that for sufficiently rapid flows, the fluid-solid system is unstable to long wavelength perturbations that appear as conduit wall oscillations of growing amplitude. One first focus will be on seismic waves from basaltic fissure eruptions within the currently implemented two-dimensional plane-strain framework. The group will then extend the model to the axisymmetric geometry appropriate for cylindrical conduits, and study seismic waves from explosive eruptions. Finally, they will calculate far-field body and surface waves and link the time dependence of equivalent single force and moment tensor representations to detailed source processes.This project is supported by the Geophysics and Petrology & Geochemistry Programs.

减轻与火山相关的风险需要详细了解岩浆通过地壳中的裂缝和导管的运输和喷发。岩浆流动激发的地震波及其与弹性壁岩石的耦合可用于将有价值的约束放在否则无法访问的火山系统的一部分上。观察到的地震信号的复杂性和对耦合流体固体系统建模的难度带来了巨大的挑战。该协作建议的目的是开发数字模型，描述可压缩的，粘性的流体通过弹性物体中狭窄的通道的高速流，以及通过固体传播地震波的传播。完全耦合流体和固体响应：弹性变形改变了导管流动的导管的横截面面积，流体压力的变化将导管壁推动和向外推动，令人兴奋的地震波。特别是，该项目组将开发出一种稳定稳定的数值方法，以依赖于时间依赖于固体的固体液体，并通过固体液体进行固定的液体，并在该孔中进行固定的液体，以实现良好的状态。该模型将包括可压缩性，声速，粘度和从气体实现的拖动的变化。该代码将首先用于探索导管壁变形在稳态喷发动力学上的作用。然后，该组将评估稳态喷发溶液的稳定性。初步分析表明，对于足够快速的流动，流体固体系统与长波长扰动不稳定，这些扰动是作为导管壁振幅的导管壁振荡而不稳定的。首先将重点放在目前实施的二维平面晶体框架内的玄武岩裂口爆发中的地震波。然后，该组将将模型扩展到适合圆柱形导管的轴对称几何形状，并研究爆炸性喷发的地震波。最后，他们将计算远场的身体和表面波，并将等效的单力和矩张量表示的时间依赖性与详细的源过程联系起来。该项目得到了地球物理和岩石学和地球化学计划的支持。