Originally posted by Nephthys
He also did it before he ate several entire planets, bro. Plus gravity well.
We don't know how strong the gravity well was, or how much stronger Nihilus grew, but we do know that Malachor's nexus is pretty powerful. We also don't know how long it took him to do this, how much it strained him, whether he gathered his energies, etc. Luke does his pretty casually, and this isn't even his prime yet.
I highly doubt the fortress was anywhere near 1200 feet in size.
It reached above the clouds and was big enough to have a hanger for starfighters.
"Your ship, my prison, that you dragged from the gravity well at Malachor V."
"The Ravager was hauled from the gravity well at Malachor V by its new master. He used it to escape imprisonment on Malachor V."
https://en.wikipedia.org/wiki/Gravity_well
"At the same time hundreds of ships, Republic and Mandalorian alike, were yanked from orbit by the creation of an irresistible gravity vortex at the planet’s core. They crashed into the surface of the world, striking with such velocity that their hulls actually penetrated several kilometers into the ground, burying the twisted wreckage and broken bodies. Tens of thousands of lives were snuffed out in a fraction of a second."
Darth Nihilus ripped it from a gravity well (I assume the gravity well being referred to was the space from the blast down into the core) so powerful it stuck the Ravager kilometers into the ground.
I assume the well was in a specific location on the planet. I really have no clue how gravity well works, so someone can correct me if I'm wrong, but based on the picture shown on wikipedia, the broad area at the top can easily represent the fleet battle while the certain point being the exact position where the Mass Shadow Generator fired down into the core. All of the ships seem to have been pulled from that large area into an immensely dense area (kilometers deep). I assume Darth Sion wasn't in the radius of the gravity well, especially since the Trayus Academy survived the destruction (while all the other underground cities were destroyed), suggesting the detonation occurred on the exact other side of the world (which makes sense, since Revan wanted to preserve the Trayus Academy).
Basically, I think there's a specific location in Malachor where the gravity is utterly ridiculous, and then the farther you get from it, the weaker the pull from the center. The ship Darth Nihilus raised would have been in the most concentrated part.
Originally posted by SunRazer
Apparently gravity well projectors can stop ships from entering hyperspace/pull them back into real space (The Complete Star Wars Encyclopedia), and I'd assume Malachor's gravity well is stronger.