When a large meteoroid entered the atmosphere at hypersonic speed it drives a shock wave. The low-frequency sound — infrasound, below the range of human hearing — can travel thousands of kilometres, letting a handful of sensors measure the energy release of an explosion that happened over another continent.
We use our own ELFO infrasound array near Western and the global International Monitoring System (IMS) built to verify the Nuclear-Test-Ban Treaty, dedicated arrays such as IS26 in Germany, and even ocean hydroacoustic stations, to detect bolides and measure their energy.
What we have found
- Infrasound and seismic records yield independent energy estimates for major fireballs — the method we applied to Chelyabinsk and many other bolides.
- Ground damage from airbursts is better described by a cylindrical line-source shock than the classical spherical blast, which changes damage predictions.
- Our measurements helped validate the Fragment-Cloud Model now used by NASA for impact-damage risk.
- The shock from the unusual Carancas impact is being used to recalibrate how impacts are detected seismically on Mars by the InSight lander.
Work on this as a student
Hunt for fireball signatures in global hydroacoustic records, or measure the shock-wave energy of shower meteors with the IS26 array.
Key publications
- Brown, P., Whitaker, R.W., ReVelle, D.O., Tagliaferri, E. 2002. Multi-station infrasonic observations of two large bolides. Geophys. Res. Lett. 29(13).
- Silber, E. & Brown, P. 2019. Infrasound monitoring as a tool to characterize impacting near-Earth objects. In Infrasound Monitoring for Atmospheric Studies (2nd ed.), 939–986.
See also: infrasound array equipment and local research at Western.