EAPSI: Analysis of Fumarole Acoustics at Aso Volcano, Japan

Mckee Kathleen F, Fairbanks AK

Investigators

Abstract

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.