An inverse warp cascade is an energetic phenomenon which could be produced by a starship's main engines.
In 2369, Enterprise chief engineer Geordi La Forge proposed initiating and inverse warp cascade to reverse the effects of a warp funnel, which he believed had transported the Starfleet vessel Hera 300 light years to the gas giant Marijne VII, where it had become trapped in the atmosphere. According to his theory, the subspace distortion from the cascade would have the effect of returning the Hera to the point where it initially entered the funnel. It was later determined that the Hera had not entered a warp funnel, however, and that Geordi was being manipulated by subspace lifeforms. (TNG: "Interface")