Gravimetric flux density is a gravimetric measurement. A high gravimetric flux density reading could be a result of a quantum singularity.

In 2369, Chief Miles O'Brien told the senior staff aboard Deep Space 9 that the Federation developed a far better way to control the flux density in the last two-hundred years. (DS9: "If Wishes Were Horses")

In 2371, the USS Voyager discovered a type 4 quantum singularity with a gravimetric flux density of 2,000%. (VOY: "Parallax")