Well, its the same thing: the inward collapse of the cavern wall forced what was contained inside (liquified gas, brine, diesel, whatever other crap that they shoved in there) to blow out. Remember, "fracking," or hydraulic fracturing, is using pressurized fluid to push petroleum out of layers of rock.

So, the salt cavern wall (solid) collapses into the well space which contains liquids, and the liquid is pushed into the cracks in the cavern wall, into the surrounding layers of rock, and pushes methane and hydrocarbons to the surface. Also, the collapse results in a destabilization of the surface overhead, resulting in the sinkhole.

The real questions are
- HOW did the cavern collapse??? LA wants to blame Texas Brine for using a cavern that they knew was unstable. LA also claims that the cavern collapse caused the seismic activity Texas Brine has already indicated that they plan to defend themselves by claiming the seismic activity caused the cavern collapse. I suspect Texas Brine is probably right, but LA does not want to agree because then people would begin asking whether the ongoing seismic activity (and it IS ongoing, obviously) may cause other collapses. I.e., what else may the government and the companies be hiding regarding the stability of the many many caverns in the salt dome (or other salt domes?)?

- How MUCH methane and oil is now rising to the surface due to the collapse? It would seem that there must be a LOT of methane down there for there to be this much bubbling in the bayou, and so far from the sinkhole area.

- Will the continuing escape of gas through existing fissures create greater instability in the region and/or create the sinkhole to further expand, and or/create additional sinkholes?