1. Fast Infrasonic Arrivals at the Long Distances from Explosions
Sergey Kulichkov1,
Laslo Evers2,
Elisabeth Blanc3,
Lars Ceranna4,
Alexis Le Pichon5
Anatoly Barishnokov 6
INFRASOUND TECHNOLOGY WORKSHOP,
BERMUDA, November 3-7, 2008

2. OVERVIEW
♦The mechanism of the formation of anomalously fast infrasonic arrivals at long distances from surface explosions is discussed.
♦ These arrivals have propagation speeds c ( c=r/T) higher than 320 m/s.
♦ These arrivals are observed in the absence of acoustic waveguides in the troposphere.
♦ It is assumed that such signals correspond to infrasonic propagation along a slightly inclined ray path having a significantly extended horizontal portion at a height of the maximum effective sound speed within the upper stratosphere (z is about 50 km).
♦ Ray theory and the Time Domain Parabolic Equation code (TDPE) are used as theoretical models.
♦ The solutions obtained are compared with experimental data on acoustic signals recorded at a long distances from 500 t tnt surface explosions and from blast site at oil depot in the UK (oil depot in Buncefield, UK) December 11, 2005.
♦ A satisfactory agreement between the theoretical and experimental data is noted.

3. FAST INFRASONIC ARRIVALS

4. Infrasonic arrivals at a distance of 635 km from explosions (500 t tnt) Experiment and Theory

5. Sound velocity and Ray paths (oil depot in Buncefield, UK, December 11, 2005)

6. Infrasonic signal from a vapor cloud explosion occurred at an oil depot near Buncefield, December 11, 2005 (r = 435 km)

7. ICADE (641 km)

8. FLERS (334 km)

9. CONCLUSIONS
♦ Fast infrasonic arrivals are observed at the different distances from explosions.
♦ TDPE code and Ray theory allow one to satisfactorily interpret the basic characteristic properties of infrasonic signals recorded at large distances from explosions.
♦ Fast infrasonic arrivals may be used to determine the site of explosion by using of only one observation site.

10. THANK YOU !