1. Session 2 Summary Infrasound from Anthropogenic Sources S. Kulichkov & C. Szuberla Infrasound Technology Workshop Hamilton Parish, Bermuda 3 November 2008

2. 3 November 2008Session 2 Summary2 Chemical Explosions Liszka A series of small-aperture arrays situated near ordinance disposal sites (< 10 T TNT ) Radiosonde & acoustic signal processing used to infer atmospheric structure Possible wave interactions with atmospheric gradients and/or turbulence Statistical propagation model (wave packets) may be useful for geolocation at regional scales (< 500 km) Fast Arrivals Kulichkov, et al. Data from blasts of up to 0.5 kT TNT are used to vet theory Non-tropospheric arrivals (1-bounce) are modeled via ray & TDPE approach Good correlation between model atmosphere used & experimental results Results explained relatively well by theory

3. 3 November 2008Session 2 Summary3 Utah Detonations Bowman & Shields Statistical study of rocket motor disposal (~40-80 T TNT ) blasts Confirms seasonal wind effects on detection Model parameter sensitivity study Adjust parameters to match results (large adjustments required) Relative amplitudes, sequence of arrival & seasonal effects modeled well Back azimuth and attenuation not so well Israeli Calibration Gitterman & Hofstetter Main test shot: ~0.08 kT TNT of old ordinance in desert (~ Aug 08) Smaller test shots ~Dec 08 Near- and far-field temporary and permanent deployment of seismoacoustic sensors Used to enhance modeling of atmosphere and blast propagation Opportunity for international collaboration on well- planned, large conventional surface explosion

4. 3 November 2008Session 2 Summary4 Airplane Noise Xiao, et al. Aircraft-induced signal at ~5 km range from ~10-70 Hz Consistent signal on all landings No similar effect for takeoff Possibly caused by –Thrust reverse –Wing-Ground interaction –Flaps Further fieldwork planned Case Studies Golden & Herrin Earthquake-induced infrasound from nearby mountain ranges –Multiple back azimuths from different features at regional/local ranges –Similar to previous results in the Andes Dispersion evidenced in arrivals at regional ranges (~150 km) from ordinance disposal site Simple model explains dominant features of signals Low-altitude duct Requires enhanced meteorological data

5. 3 November 2008Session 2 Summary5 Wind Turbines Stefanova Europe, Antarctica and remote sites are faced with large windfarm infestation Rising fuel costs & environment forces make this a reality Mostly, well-defined azimuth & frequency So far the impact has been “we deal with it” Placing wind towers atop infrasound arrays will be more problematic Signal processing can ameliorate many of the effects Common Themes Ordinance disposal sites provide excellent targets of opportunity Many studies done at regional range –Understand this range first –Longer ranges will follow Underlines importance & impact of portable array deployments