An oscillating bubble of gases, such as formed by an explosion in water. Most marine seismic sources generate bubbles; the bubble oscillation frequency is given by the Rayleigh-Willis relation (see Figure R-5). Various arrangements such as wave-shape kits are used to attenuate bubble effects or (as with Maxipulse) to correct for them. Bubble oscillations can be prevented if the source is so close to the surface that the gases vent before the bubble collapses. This occurs if an explosive of w pounds of dynamite is fired shallower than d ft, where d=3.8w1/3. See Figure B-10.