About 2 hours into 2012, John Cusack and his companions have escaped the land crumbling beneath their feet, collapsing high rises, the land crumbling beneath their car, a massive volcano eruption, and the land crumbling beneath their airplane at take-off. They're on their way to Tibet, where a fleet of arks has been built to save select humans and animals from the enormous tidal waves that will follow the earthquakes (How enormous? There's a reason the ships are up there in Tibet). The group needs to land mid-way between the US mainland and China to refuel their plane, but unfortunately they find Hawaii covered in lava. What can our heroes do now? Surely they're doomed to a watery death in the middle of the Pacific.
When they emerge from the Hawaiian volcano smoke, they find land below them! The earth's crust has shifted so drastically that all of China has moved thousands of kilometers east and is now directly underneath the airplane. Miraculously, this shift took place without any accompanying earthquakes in Tibet, meaning the arks are perfectly safe and habitable.
Implausible, certainly, but then looking for plausibility in a Roland Emmerich film is like seeking veal steak in Pushkar. Remember the director's 1996 hit, Independence Day, where the evil alien mothership is destroyed after Jeff Goldblum infects it with a virus? Goldblum flies to the ship, connects to its main computer, and somehow transfers the virus from his Mac laptop to the alien operating system without any compatibility issues hindering the operation.
Independence Day was inspired by H.G.Wells' War of the Worlds, but used a cyber virus to destroy the aliens instead of a real infection. A few years later, Steven Spielberg adapted the novel with Tom Cruise in the lead role. Spielberg's War of the Worlds is about a father trying to reconnect with his young daughter and rebellious son while surviving a catastrophe that threatens the planet. 2012 is also about a father trying to reconnect with his young daughter and rebellious son while surviving a catastrophe that threatens the planet. Hollywood loves stories about fathers trying to reconnect with children, and it loves catastrophes that threaten the planet.
The original War of the Worlds had a simple plot: aliens invade and kill lots of people, before being destroyed by earthly infections to which they have no resistance. Spielberg added a variation: the aliens have buried giant machines inside the earth thousands of years earlier, and only need to man these craft in the present age. This created a logical problem: if the aliens had visited earth previously, they must've learned about those deadly bacteria. Why, then, did they return without first finding a vaccine or remedy?
Moral of the story: in making a blockbuster, if you have a choice between plausibility and some cool special effects, go with the cool special effects.