It will be like any large body of water. If it finds a crack, it will rush through it to seek a position of rest. (lowest point).
As it is rushing through, it will enlarge the path. That means more, and more, and more, and it never stops until balance (equilibrium) is achieved.
No doubt about that.
But that could be hours, days, weeks, months in some respects. I suspect it will be less than a year and at least less than 3 or so years.
The Sumatran instant undersea cliff was just a hint of things to come, imho.