If you need a rough approximation of what 6600 cubic inches pressurized to 2000 psi of air exploding is like, imagine that a standard SCUBA tank is pressurized to 3000 psi and is roughly 80 cubic feet at one atmosphere of pressure 80 cubic feet = 138240 cubic inches. 6600 cu in * 2000 psi = 1.1*10^6 ft lbs of force. The SCUBA tank if it explodes would be 138240 * 3000 = 3.456*10^7 ft lbs of force. The SCUBA tank is an order of magnitude larger, however this does not take away from the power of the air guns. Think of the tank as a bomb whereas the air guns are a controlled source. Regardless of the reference the air guns are still dangerous and they are kept at 2000 psi almost at all times. This requires one powerful air compressor. We refill the air guns every 20s (or 50m whichever comes first), so we need a large volume compressor to basically instantaneously fill the guns to be ready to fire for the next shot. If we were using the volume of the SCUBA tank we would need a compressor that was an order of magnitude greater in volume output and 1.5 times more powerful. The point is, is this is not JAWS and we do not condone exploding SCUBA tanks as our source material.
The air guns are relatively deep penetration sources, operating at 100 to about 1200 Hz, to identify subsurfacegeologic layers and define the subsurface structure. In studies that require less resolution but substantial penetration, the air gun is usually preferable as compared to a water gun, because it is far more efficient at producing low frequency energy. It can be used in fresh or brackish (less saline) water found in lacustrine and estuarine environments. Both air guns (and water guns) can be used in shallow w
ater surveys and relatively deeper water environments, achieving resolution on the order of 10 to 15 meters and up to 2000 meters penetration. With proper tuning, the air guns work well in a wide variety of bottom types. Minimum operating water depths of about 10 meters are possible in acoustically “soft” bottoms. In areas with acoustically hard