Chemical explosion in the AZF fertiliser factory near Toulouse, France  

DATE: 21 September 2001

SOURCE TIME:   08:15 UTC

LATITUDE : 43.62 N

LONGITUDE : 1.45 E

Topographic map showing the I26DE infrasound station in the Bavarian Forest and the position of the explosion in Toulouse. The yellow line marks the great circle between the source and station which lie around 1100 km apart. Source: BGR

This shows the results of the frequency wave number analysis of the signals registered by the five separate stations at I26DE. The maximum signal energy shown in yellow at an azimuth of 245.4 degrees points in the direction of the explosion. Source: BGR

The signals from the pressure wave which spread out in the earth’s atmosphere from the source of the explosion are picked up by the five stations of the I26DE infrasound array in the Bavarian Forest after approximately one hour. The first arrival of the incoming wave (in red) is overlain by signals from another infrasound source which were recorded simultaneously, and could only be clearly identified after determining the direction. The signal groups that follow with strong amplitudes are also generated by the explosion in Toulouse. The individual signals arrive at the infrasound array at different times because of the different travel paths taken by the pressure waves in the atmosphere.  
Quelle: BGR