canon à air

CONT: Un navire de prospection pétrolière est équipé d'instruments [...] dont le canon à air, ou autre source d'ébranlement pour la sismique, immergé à l'arrière.
CONT: Dans le canon à air le train d'ondes est obtenu par libération brutale de l'air comprimé dans l'eau [...]

OBS: As the gun is trailed behind a boat, air is released, making a low-frequency popping noise, which penetrates the subsurface rock layers and is reflected by the layers. Sensitive hydrophones receive the reflections and transmit them to recording equipment on the boat.
OBS: Air guns have also been adapted for lowering in a borehole or pushed down into the marsh ... Air guns are also used in small tanks of water which are set on the surface of the ground as a seismic source on land.