HR: 0830h
AN: U31B-0008    [PDF]
TI: Avalanche-Generated Infrasound Signals
AU: * Scott, E
EM: scotte@imlinc.com
AF: IML Air Science, 555 Absaraka, Sheridan, WY 82801 United States
AU: Hayward, C
EM: hayward@smu.edu
AF: Department of Geosciences Southern Methodist University, Dedman College PO Box 0396, Dallas, TX 75275-0395 United States
AB: Snow avalanches produce sub-audible acoustic pressure fluctuations in the low frequency infrasound spectrum that can be detected at significant distances. Although such signals have been previously observed and described, information detailing the characteristics of avalanche generated infrasound signals is scanty. During the winters of 2000/2001, 2001/2002, and 2002/2003 infrasonic monitoring systems operated at several locations in the Rocky Mountain West and collected data aimed at characterizing infrasonic signals produced by avalanche activity. Remote DC powered measurement systems providing a 1 - 10 HZ band limited infrasound signal were deployed within 2 kilometers of controlled and observed avalanche slide paths. Infrasonic microphones coupled to porous hose noise reducing filters were placed on the ground and subsequently covered by snowfall. Results obtained from these efforts have shown avalanche-generated infrasound signal amplitude levels approaching a 20 ębar dynamic range while occupying a 1 - 8 Hz frequency band. Additional infrasound insights on various avalanche control mechanism signatures, potential interfering event signatures, and ambient noise levels were also obtained. The catalog of data has been utilized to develop avalanche identification signal processing algorithms. Knowledge gained from research results will be applied during the 2003/2004 winter through the operation of a prototype near real-time avalanche alarming system on Teton Pass, Wyoming. Research efforts related to this study will were funded via a Small Business Innovative Research award obtained through the National Oceanic and Atmospheric Administration within the U. S. Department of Commerce.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 1863 Snow and ice (1827)
SC: U
MN: 2003 Fall Meeting