Geophysics

The Sounds of Waves and Meteors

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Science  19 Jan 2001:
Vol. 291, Issue 5503, pp. 399
DOI: 10.1126/science.291.5503.399a

The seismology division of the Royal Netherlands Meteorological Institute operates an array of micro-barometers that detects low-frequency (0.002 to 40 hertz) sound waves traveling through the atmosphere. This frequency range covers infrasonic disturbances inaudible to humans, such as distant nuclear explosions, and similar arrays are being installed worldwide as part of the Comprehensive Nuclear Test Ban Treaty. The Deelen array covers about 1.5 square kilometers and incorporates five porous hoses attached to each micro-barometer to reduce noise from atmospheric wind.

Evers and Haak report detection on 8 November 1999 of a discrete 0.15 Hz component along with a continuous 0.19 Hz component. The 0.15 Hz signal came from the northeast, and the source was identified as a meteor explosion in the atmosphere over northern Germany, as confirmed by eyewitness accounts and photographs. The higher frequency signal came from the northwest (the northern Atlantic) and was associated with standing ocean waves coupled to the atmosphere (these sounds are called microbaroms). The authors estimated that the meteor explosion occurred at about 15 km in altitude and released energy equivalent to about 1.5 kilotons of TNT, within the range for nuclear explosions. — LR

Geophys. Res. Lett.28, 41 (2001).

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