I simply don't understand the negative reviews this movie has gotten. It's a far better written and acted movie than most of the sci fi coming out of big-budget Hollywood. For sure, as a disaster movie it far outshines any silly train-wreck of a movie from Jerry Bruckheimer or Michael Bay.
As far as the writing, the plot does a great job with implying a major disaster while resisting the urge to explain. The viewer is given everything he needs to figure it out on his own, at his leisure. I think that part of the problem with some reviewers is that they were expecting the crisis to turn into an alien attack or something equally silly, when the much simpler answer is far more appropriate and plausible, while still being highly destructive. *****SPOILER WARNING*****
So what is this huge catastrophe, presaged by seismic events and managing to both shut down air travel and trigger a panicked exodus from the northwest region of the USA? Nothing more or less than the eruption of Mt. Ranier, that huge, beautiful, not-so-dormant volcano that overlooks Seattle and Tacoma and one day will wipe both off the face of the Earth. It has been called the "most dangerous volcano in the world" and is much larger than Mt St. Helens. That's it. I'm not a geologist and all my science learning has been in the biological sciences, and I managed to figure it out before the end of the movie. That I had to figure it out, and that it turned out to be something so simple yet so appropriately catastrophic absolutely delighted me. And that ending, where the protagonist and his girl are just barely outrunning a lethal pyroclastic flow from yet another eruption? A perfect ending for a thoughtful movie that manages to do just about everything right.
Just because some critics were just too stupid or too slow to figure it out on their own, and just because they were disappointed when the beginning didn't presage an extraterrestrial invasion or some Mayan prophecy doesn't make their misbegotten reviews carry any more weight. Their opinions can be safely ignored. It's a great movie and much less complicated than it originally appears. And like all good fiction, it ends on a highly satisfying note even if it left the survival of the protagonist in doubt. Watch it.