Because Sledgehammers Suck
It takes 3 minutes to deploy and recover a Betsy Gun. Or you could swing your sledgehammer 100 times per source point (assuming you're Thor, and can move a 16 lb sledgehammer 45 mph). The BFG-1000 series is designed to maximize data quality, and excite the broadest spectrum of waves for any explosive seismic source that doesn't require a blasting license. Each part of the BFG-1000 has been designed to optimize the seismic wavefield, reduce post-ignition surface noise, and maximize the safety of the users. Betsy Guns produce shear waves (SV) which can be detected on vertical component geophones, and can processed in tandem with the P-waves to yield Vp/Vs and other physical properties. Betsy Guns produce Rayleigh waves down to 2 Hz, enabling MASW imaging past 100 m depth, another thing a sledgehammer will never do.
Superior Low-Frequency for MASW or Full Waveform Inversion
Betsy Guns produce superior data on the low end of the spectrum, and are the best source for shallow surface wave analysis including SASW, MASW and ReMi. Above: 48 channel (3m spacing) Betsy Gun shot gather showing rayleigh waves and SV.
Powerful High-Frequency P-waves for High-Resolution Imagery
This is the same source gather as above, only the top 240 ms are shown here. Left panel shows raw data. Subsequent panels are high-passed with progressively higher corner frequency, 100Hz, 125Hz, 150Hz and 175Hz.