Measurement and characterization of infrasound from a tornado producing storm

J Acoust Soc Am. 2019 Sep;146(3):1528. doi: 10.1121/1.5124486.


A hail-producing supercell on 11 May 2017 produced a small tornado near Perkins, Oklahoma (35.97, -97.04) at 2013 UTC. Two infrasound microphones with a 59-m separation and a regional Doppler radar station were located 18.7 and 70 km from the tornado, respectively. Elevated infrasound levels were observed starting 7 min before the verified tornado. Infrasound data below ∼5 Hz was contaminated with wind noise, but in the 5-50 Hz band the infrasound was independent of wind speed with a bearing angle that was consistent with the movement of the storm core that produced the tornado. During the tornado, a 75 dB peak formed at ∼8.3 Hz, which was 18 dB above pre-tornado levels. This fundamental frequency had overtones (18, 29, 36, and 44 Hz) that were linearly related to mode number. Analysis of a larger period of time associated with two infrasound bursts (the tornado occurred during the first event) shows that the spectral peaks from the tornado were present from 4 min before to 40 min after tornadogenesis. This suggests that the same geophysical process(es) was active during this entire window.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't