There was a posting on here about finding a 10 Hz component in the RS pressure wave due to staging of the quarry blast (I cannot easily find now).
I ran across this overhead view of one type of blasting event I thought some folks might enjoy.
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Yeah I think I posted an example the first time I detected (sorry… realised I detected) the detonation interval in a mine blast. It’s more common than when I first thought - the first one I realise was very distinct but now I’m aware of it it’s easier to see. It’s not apparent in all blasts though so some must have enough variation in their fuse length (or something) not to show up in the spectrogram.
For example in this blast at Cadia Gold Mine, the detonation interval is 0.05s (20Hz) as can be seen from the FFT and the Spectrogram. 40 Hz and a weak 10Hz (subharmonic?) show up in the spectrogram as well.
Here’s another example with two distinct detonation frequencies (perhaps different in the x and y directions?):
But sometimes there’s no distinct detonation interval, for example:
I love watching mine blasts especially in slow motion. It must be related to pyromania or something, cause I like watching fires as well. ;o)
Al.
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