It looks like the Karathen is at least 3,200m long, so I think we can take the VFX designers words at face value. It's upper portion looks like it's around half of its length, while its width is half of that portion, so around 800m wide. Mass-wise, the Karathen had to pull itself onto the seafloor and basically had no buoyancy at all, so it's probably much denser than seawater. Due to its high density and its arms/legs/tentacles adding to its mass, I think we can use a cylinder's likely higher volume of a 400m radius and 3200m height for 1,610,000,000m^3, and a lesser density of 1,000kg, so we can get around
1.61e+12kg or
1,610,000,000 metric tons.
She's a pretty hefty crab lady.
If we go with the hollow pocket being somewhere around the actual center of the earth, or around 6,378.1 km from the surface, a timeframe of 150 seconds would give it an average speed of
124 mach, or around
42,520 m/s.
I'm not exactly sure how we can determine how strong she had to exist in and move that fast out of the core, and I've been working on this for a while, but I think it has to do with Drag Force and the power to overcome it based on
this (Pd=Fd*v=1/2¤ü*v^3*A*Cd) equation. It's density is around 12,600-13,000kg/m^3, so it's ¤ü can be said to be 13,000. It's area is basically the front area of the Karathen, let's go with a 800m wide circle/400m radius for an area of 503,000 m^2, it's probably larger but I feel this is good enough.
The drag coefficient is what's tripping me up, since it's based on Reynolds number and viscosity, and the inner core's viscosity
~ 2-7 x 10^14 Pascal*seconds, compared to water's 8.90 x 10^-4 or air's 1.81 x 10^-5. I'm just going with 1 because I don't know how that works.
So what I'm left with is 1/2 x 1.61e+12 x 503000 x 42520^3, which is
3.2365129e+31 watts or joules/second, or
Low 5-B/Small Planet level.
Either I messed up or holy shit what.