Subspace shock wave

From Memory Alpha, the free Star Trek reference.

A subspace shock wave is a violent compressional wave caused by a massive energy discharge which travels through the medium of subspace. These phenomena are typically created by the destruction of large planetary or stellar bodies.

In 2293, a subspace shock wave was created from the explosion and partial destruction of the Klingon moon, Praxis. The effects of the shock wave caused severe damage to Qo'noS, as well as minor damage to the nearby USS Excelsior. (Star Trek VI: The Undiscovered Country; VOY: "Flashback")

The unusual supernovae caused by the Q Civil War of 2373 generated subspace shock waves. The shock waves collapsed the USS Voyager's warp field, preventing its escape and causing severe damage. (VOY: "The Q and the Grey")

The subspace shock wave was invented because a conventional shock wave traveling at sublight speeds would have taken years to reach the Excelsior.