Computational simulations of volcanic eruptions and infrasound

火山喷发在大气中产生声波，在固体地球中产生地震波。这些波可以在离火山一段安全距离的地方被记录下来，并被用来限制喷发过程，否则研究就会遮盖住这些过程。该项目将开发计算机模拟，模拟岩浆通过固体地球中的火山管道上升，并喷发到大气中，同时捕捉声波和地震波。大多数目前的喷发模拟都是基于简化的近似，比如不可压缩的流体和刚性固体，它们消除了波浪。该项目的模拟结果可用于改进火山监测、数据解释和危险评估。该项目将为博士生和博士后学者提供培训，面向公众的外联活动包括在当地小学科学之夜进行与火山有关的演示，为符合下一代科学标准的小学教科书撰写STEMTauight文章，以及斯坦福大学的科学家问答网页。喷发模拟将利用最先进的空气声学程序，最初设计用于研究湍流喷流的声音辐射和喷气发动机释放高压气体产生的冲击。该程序将被修改，通过耦合到模拟岩浆上升、降压和破碎的非稳定管道流动程序来研究火山喷发。火山喷发和斯特朗博勒火山喷发的模拟将用于1。评估常用声源模型的有效性，如点单极子模型和线性声学模型；量化湍流卷吸对次声产生的影响(促进视觉和次声数据的联合解释)；和探测地下喷发过程，如浅层储层的降压率，提供对气体和岩浆如何在喷口附近临时储存、加压和释放的洞察；还可以识别大型火山爆炸中碎裂表面沿管道下降的迹象。利用地震表示理论，将管道内压力和动量的变化转化为弹性波动方程中等效的地震矩张量和力源。将推导出对喷发过程的地震约束，如碎裂，以补充次声约束。该项目由地球物理和岩石学/地球化学计划支持。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Volcanic eruptions generate sound waves in the atmosphere and seismic waves in the solid Earth. These waves can be recorded at a safe distance from volcanoes and used to constrain eruptive processes that are otherwise obscured from study. This project will develop computer simulations of magma ascent through volcanic conduits in the solid Earth and eruption into the atmosphere that also capture sound and seismic waves. Most current eruption simulations are based on simplifying approximations, like incompressible fluids and rigid solids, that eliminate waves. Simulation results from the project can be used to improve volcano monitoring, data interpretation, and hazard assessment. The project will provide training for a PhD student and postdoctoral scholar, and outreach activities for the general public include volcano-related demos at local elementary school science nights, STEMTaught articles for an elementary-school-level textbook meeting the Next Generation Science Standards, and a Stanford Ask A Scientist webpage.The eruption simulations will utilize a state-of-the-art aeroacoustics code originally designed to study sound radiation by turbulent jets and shocks created by discharge of high pressure gas from jet engines. The code will be modified to study volcanic eruptions by coupling to an unsteady conduit flow code that models the ascent, depressurization, and fragmentation of magma. Simulations of vulcanian and strombolian eruptions will be used to 1.) assess the validity of commonly used acoustic source models like the point monopole and linear acoustics; 2.) quantify the effects of turbulent entrainment on infrasound generation (facilitating joint interpretation of visual and infrasound data); and 3.) probe subsurface eruptive processes like the rate of depressurization of shallow reservoirs, providing insight into how gas and magma are temporarily stored, pressurized, and released near the vent; also, identify signatures of the descent of the fragmentation surface down the conduit in large vulcanian explosions. Seismic representation theory will be used to convert pressure and momentum changes within the conduit to equivalent seismic moment tensor and force sources in the elastic wave equation. Seismic constraints on eruptive processes like fragmentation will be derived to complement infrasound constraints. This project is supported by the Geophysics and Petrology/Geochemistry programs.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.