This is a story of a mathematician who found a way to predict earthquakes. He finds out that there will be a major earthquake in California (where he lives). After checking this prediction using CalTech's computer he notices that his own results is slightly different from the computer's. While he tries to figure out the reason of this discrepancy, other people are leaving the California in a great hurry. Being obsessed with the problem, he does not notice the panic, ignoring the fact that he might be in danger himself. Finally the earthquake begins exactly at the predicted time and date. After it is over, mathematician notices that the computer's version was correct : the rest of USA lays beneath the sea...

There is no actual mathematics in this story. Anyway it is only a joke. I think there is no reason to look for mistakes in it.