EAPSI: Analysis of Fumarole Acoustics at Aso Volcano, Japan

该奖项支持表征喷气孔声音的研究，以促进对火山过程产生的声音的理解。喷气孔是活火山环境中的喷口，在温度超过100°C时释放蒸汽和其他挥发物（即二氧化碳、二氧化硫等）。从喷气孔喷出的加压气体也会产生声波。喷气孔的声学和脱气可以告诉我们当前和未来的火山活动，因为声学和火山排放物的变化可能是更大的火山爆发的前兆。火山喷流噪声是对喷发过程中产生的压力波动的直接测量，可以提供喷发柱本身的信息。射流噪声是由持续的动量驱动的流体流过喷嘴（例如喷气发动机的喷嘴）产生的，而火山射流噪声是火山射流在持续喷发期间产生的持续声信号。在后者中，喷口是火山的喷口。实验室喷气发动机噪声声学揭示了喷气噪声与喷气发动机之间的关系。S物理特性（速度、直径、质量通量等）。然而，人们对火山喷流和火山喷流噪声之间的关系仍然知之甚少。这项研究将在京都大学Aso火山实验室的Takahiro Ohkura博士和Akihiko Yokoo博士的指导下进行。火山声学界的目标之一是定量地将火山喷流的声音与火山喷发本身联系起来，但由于火山喷流和现场环境的复杂性，这一目标一直难以实现，因此需要额外的数据。该项目旨在通过调查火山喷发活动产生的喷射噪声来提高我们对火山喷流和喷发柱的理解，然后将这些信息传播给各个火山观测站和一般科学界。我们将在日本的麻生火山部署两个次声麦克风阵列，其中一些与地震仪搭配使用，以观察和表征喷气孔声学并确定其地震声学特征。前视红外辐射计（FLIR）摄像机也将用于观察气体发射动力学，因为气体是人眼看不见的。NSF EAPSI奖是与日本科学促进会合作资助的。

This award supports research to characterize the sound from fumaroles to advance the understanding of sound produced from volcanic processes. Fumaroles are vents in active volcanic environments that issue steam and other volatiles (i.e. carbon dioxide, sulfur dioxide, etc.) at temperatures greater than 100°C. Pressurized gas jetting out of fumaroles also produces sound waves. Fumarole acoustics and degassing can inform us about current and future volcanic activity, as changes in the acoustics and volcanic emissions can be precursors to larger volcanic eruptions. Volcanic jet noise is a direct measure of the pressure fluctuations produced during an eruption and can provide information on the eruption column itself. Jet noise is produced by sustained, momentum-driven fluid flow through a nozzle, such as that of a jet engine, while volcanic jet noise is a sustained acoustic signal produced from the volcanic jet during sustained eruptions. In the latter, the nozzle is the vent of the volcano. Acoustics of laboratory jet engine noise reveals a relationship between the jet noise and the jet?s physical characteristics (velocity, diameter, mass flux, etc.). However, this relationship is still poorly understood for volcanic jets and volcanic jet noise. The research will be conducted under the mentorship of Dr. Takahiro Ohkura and Dr. Akihiko Yokoo of the Aso Volcanological Laboratory at Kyoto University. One of the goals of the volcano acoustics community is to quantitatively relate sound from volcanic jets back to the eruption itself, but due to the complexities of volcanic jets and field environments this goal has been elusive, thus additional data are needed. This project aims to advance our understanding of volcanic jets and eruption columns by investigating the jet noise produced by fumarolic activity, and then disseminate this information to various volcano observatories and the general scientific community. We will deploy two arrays of infrasound microphones with some collocated with seismometers, at Aso Volcano, Japan to observe and characterize fumarole acoustics and determine their seismo-acoustic signature. Forward Looking Infrared Radiometer (FLIR) cameras will also be used to observe gas emission dynamics, as gases are invisible to the human eye. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.