One of the issues about 9/11 is that there was somebody to be mad at. When a tsunami hits (tidal wave is actually a better name for them, though it is out of vogue these days), there is nobody to be angry at. The US wouldn't have made nearly the same kerfuffle over it had it been a natural disaster. Sure, we would have had numerous commissions, investigations, lawsuits, and so forth, but not the same response as 9/11, since there would be nobody to seek vengeance against.

Of course, as the Economist and others have noted, there is more to it than that. The second most deadly terrorist attack in the US was Oklahoma City, which was a right-wing attack. In fact, there have been several times as many terrorist attacks in the last two decades by right-wing groups in the US as by any foreign group. However, when the FBI decided that they were going to step up surveillance on terrorist groups, they were told that they were not allowed to include right-wing group, according to the Economist. That's pretty consistent with the response to Oklahoma City. As long as it was thought to be foreign, the talking heads were shouting. As soon as it turned out to be a domestic right-wing group, the talking heads were changing the subject.

9/11 was the perfect attack for those who want to beat a drum: Somebody did it, we were the target, and it wasn't one of us.