Abstract by Margaret Smith
Physics and Astronomy
Noise from Ground-based Exploding Balloons
Volcanos pose hazards to nearby communities. One way to monitor them is by recording their acoustic signals. These signals often have less background noise than seismic signals, which allows them to be more closely tied with volcanic events. To learn how to interpret these signals, we tested measurement techniques on small scale explosions from balloons filled with oxyacetylene gas. The balloons were placed on the ground or in holes, and the sounds were measured at distances of 100, 130, and 160 m as well heights of 0.01, 1.2, 2.4, and 3.6 m. The direct blast wave amplitude increases with height while the amplitude of the secondary wave decreases with height. The secondary wave results because the sound is propagating over a grass covered field. This study will provide insights into different types of acoustic signals produced by ground-based explosions.