Volcanic jet noise: Linking field and laboratory experiments

火山爆发是动态和复杂的，使监测和了解其源过程具有挑战性。次声波或低频声波正越来越多地用于监测和研究火山爆发。火山喷流是火山喷流噪音的多产制造者，火山喷流噪音是由火山喷口的湍流产生的。在2018年基拉韦厄东裂谷带喷发期间，人们广泛听到火山喷流的噪音。尽管它的使用越来越多，但火山喷流噪音的许多问题仍然存在。研究人员将进行一系列系统的现场和实验室实验，以解决火山喷流噪音的基本问题，以及解释火山次声数据时通常做出的假设。实验室实验将在项目合作者LMU（慕尼黑，德国）的独特设施中进行，该设施可以在受控源参数下再现气体和粒子射流。在意大利的斯特龙博利火山，研究人员将检查喷发的喷射，并确定喷射噪音辐射模式。实验室和现场的观测结果将用于解释和确定基拉韦厄和斯特龙博利火山喷发的源参数（例如喷流速度和通量），以及以前收集的火山次声数据。项目结果将对阿拉斯加和夏威夷火山观测站的灾害监测产生重大影响，项目结果将向这些地区的公众公布，并将开展广泛的国际合作和培训。该项目将整合独特的实验室和火山喷流噪音的现场观测，为火山爆发提供新的见解。实验室实验将首次模拟火山喷流噪声的产生，同时改变声音影响参数，如颗粒浓度，颗粒形状，通风口几何形状，温度和马赫数。在意大利斯特龙博利火山进行的实地试验将利用有利的地形和可靠的喷发活动，以及提供关键的相应高速视觉和红外图像，来处理假定的火山喷流噪音的高度定向性。研究人员还将利用2018年基拉韦厄裂缝喷发期间收集的近源次声和视觉数据。通过结合这三个数据集，研究人员将确定火山喷流噪音的主要特征和复杂性，包括特征频谱、高度定向的声音辐射和独特的波形特征。这些分析将有助于确定：1）将喷流速度与声功率联系起来的新的比例定律; 2）改进喷发源限制，如颗粒含量和喷流直径，从而对了解和监测世界各地的火山喷发产生直接影响。该奖项由极端事件预测和复原力（PREEVENTS）项目共同资助。该奖项反映了NSF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 are dynamic and complex, making both monitoring and understanding their source processes challenging. Infrasound, or low frequency sound waves, is becoming increasingly used to monitor and study volcanic eruptions. Volcanic jets are prolific producers of volcanic jet noise, the sound produced by turbulent flow from a volcanic vent. Volcanic jet noise was heard extensively during the 2018 Kilauea East Rift Zone eruption. Despite its increasing use, many questions on volcanic jet noise remain. The investigators will perform a systematic set of linked field and laboratory experiments to address fundamental questions on volcanic jet noise and assumptions typically made when interpreting volcano infrasound data. The lab experiments will be performed at the unique facility of project collaborator LMU (Munich, Germany) that can reproduce gas and particle jets under controlled source parameters. At Stromboli Volcano, Italy, the researchers will examine jetting from eruptions and determine the jet noise radiation pattern. The observations from the lab and field will be used to interpret and determine source parameters (e.g. jet velocity and flux) for eruptions at both Kilauea and Stromboli, as well as previously collected volcano infrasound data. The project results will have significant implications for hazard monitoring at volcano observatories in Alaska and Hawaii, the results will be presented to the general public in those regions, and broad international collaboration and training will occur. This project will integrate unique lab and field observations of volcanic jet noise to provide new insight into volcanic eruptions. The lab experiments will, for the first time, simulate the generation of volcanic jet noise while varying sound-influencing parameters such as particle concentration, particle shape, vent geometry, temperature, and Mach number. The field experiment at Stromboli Volcano, Italy will address the assumed highly directional nature of volcanic jet noise using advantageous topography and reliable eruptive activity, as well as providing critical corresponding high-speed visual and infrared imagery. The investigators will also capitalize on near-source infrasound and visual data collected during the 2018 Kilauea fissure eruption. By combining these three data sets, the researchers will determine the principal features and complexities of volcanic jet noise, including the characteristic frequency spectra, highly directional sound radiation, and unique waveform characteristics. These analyses will help determine 1) new scaling laws relating jet velocity to acoustic power and 2) improved eruption source constraints such as particle content and jet diameter, thus having direct implications for understanding and monitoring of volcanic eruptions worldwide. This award is cofunded by the Prediction of and Resilience against Extreme Events (PREEVENTS) program.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.