Computational simulations of volcanic eruptions and infrasound

火山爆发在大气中产生声波，在固体地球中产生地震波。这些波可以在与火山保持安全距离的地方被记录下来，并用于限制喷发过程，否则就无法进行研究。该项目将开发岩浆在固体地球上通过火山管道上升和喷发到大气层的计算机模拟，同时捕捉声波和地震波。目前大多数火山喷发模拟都是基于简化的近似，比如不可压缩流体和刚性固体，可以消除波浪。该项目的模拟结果可用于改进火山监测、数据解释和危害评估。该项目将为一名博士生和博士后学者提供培训，并为公众提供推广活动，包括在当地小学科学之夜进行火山相关演示，为符合下一代科学标准的小学教科书编写stemteach文章，以及斯坦福问科学家网页。火山喷发模拟将使用最先进的航空声学代码，最初设计用于研究由喷气发动机排出的高压气体产生的湍流射流和冲击产生的声辐射。该代码将被修改，通过耦合一个非定常管道流动代码来研究火山喷发，该代码模拟岩浆的上升、降压和破碎。火山喷发和斯特龙火山喷发的模拟将用于1.评估常用声源模型的有效性，如点单极子和线性声学；2)量化湍流夹带对次声产生的影响（促进视觉和次声数据的联合解释）；3)探测地下喷发过程，如浅层储层的减压速率，从而深入了解气体和岩浆是如何在火山口附近暂时储存、加压和释放的；同时，在大型火山爆炸中，识别碎片表面沿管道下降的特征。地震表示理论将用于将管道内的压力和动量变化转换为弹性波动方程中的等效地震矩张量和力源。将推导出对破碎等喷发过程的地震约束，以补充次声约束。该项目由地球物理学和岩石学/地球化学项目支持。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.