Recalled seeing your post on Lake Superior re California size and was thinking about this. Of course, where it could orientates itself as an overlay to California, if it happened, has different implications; obviously none of them good. Yet consider if it was adjacent to the coast with access to the sea.
Lake Superior (quoted) contains 2,900 cubic miles +/- of water and has average depths of up to 483 feet (147 metres) with maximum depths 1,276 feet (389 metres).
Assuming that the 'Session' referenced includes not just the physical area but the cubic mass coupled to adjacent said coastal access, the outward pressure displacement on the sea would be unthinkable as a Tsunami reaches out. However, this would be nothing compared with the immediate rush to fill the created void with 2,900 cubic miles of sea water trying to reach an equilibrium balance to the displacement of this created Superior sized void. This inward flowing Tsunami would contain near unfathomable forces with mass spillover to other regions, regions like the Central Valley or other.
Yeah, it would look like a 'Hell' on earth indeed.
Consider this alternate perspective of the East coast with this mass displacement possibility (a further view is offered for those who know the Great Lakes):
Lake Superior has as much water as the rest of the Great Lakes combined – plus three more Lake Eries.