Audible acoustics from low-magnitude fluid-induced earthquakes in Finland

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Authors

Oliver D. Lamb , Jonathan M Lees , Peter E Malin , Tero Saarno 

Abstract

Earthquakes are frequently accompanied by public reports of audible low-frequency noises. In 2018, public reports of booms or thunder-like noises were linked to induced earthquakes during a Engineered Geothermal System project in the Helsinki Metropolitan area. In response, two microphone arrays were deployed to study these acoustics while stimulation at the drill site continued. During the 11 day deployment, we find 39 earthquakes accompanied by recognizable atmospheric acoustics. Moment magnitudes of these events ranged from -0.07 to 1.87 with located depths of 4.8 to 6.5 km. Analysis of the largest event revealed a broadband frequency content, including in the audible range, and high apparent velocities across the arrays. We conclude that the audible noises were generated by local ground reverberation during the arrival of seismic body waves. The inclusion of acoustic monitoring at future geothermal development projects will be beneficial for studying seismic-to-acoustic coupling during sequences of induced earthquakes.

DOI

https://doi.org/10.31223/X5M301

Subjects

Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Keywords

Finland, seismo-acoustic coupling

Dates

Published: 2021-02-03 20:10

Last Updated: 2021-03-29 21:07

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License

CC BY Attribution 4.0 International

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