Topographic Effects of Infrasound Wave Propagation
Dr. Jeffrey B. Johnson
Infrasound is long wavelength sound, inaudible to humans, which is widely used in volcano monitoring. Infrasound radiation is directly correlated with physical processes occurring at a volcanic vent and may be used to determine volcanic activity levels. Volcán Villarrica, Chile, has an open vent and active lava lake, which is an excellent source of powerful and continuous infrasound. One of the research goals of our January 2020 expedition to Villarrica was to determine the influence of intervening topography on the amplitude and spectral content of infrasound data recorded far from the vent. To address this question, we installed a 23-sensor, 2-km linear array perpendicular to the source-receiver propagation path. The 23 sites represent varying degrees of topographic interference, in the form of mountains between the sensors and the volcanic vent. The infrasound Gems sensors, which have onboard data recording, GPS, and signal conditioning, were designed, built, and deployed by the research team. The data show a strong correlation between infrasound character and topographic interference, which we are working to understand and should inform the placement of future installations.
Mock, Jerry C.; Anderson, Jacob; Johnson, Jeffrey B.; and Gauvain, Scott J., "Topographic Effects of Infrasound Wave Propagation" (2020). 2020 Undergraduate Research Showcase. 123.