An Earthquake in Manhattan?

People laugh when I talk about the possibility of a serious earthquake in Manhattan because the last big one (5.5 on the Richter magnitude scale) was in 1884. But then I read an article (click here) that notes we get a significant earthquake just about every 100 years, which would mean we are about 24 years overdue. I emailed the Lamont-Doherty Earth Observatory about this article and Senior Science Writer Kevin Krajick wrote back that "The article you cite is pretty accurate...However, the return time of M4 or M5 quakes is not as well defined as it suggests. It could be 100 years. Or it could be several hundred years; no one knows the answer." As for the effect on the city, the New York City Area Consortium for Earthquake Loss Mitigation states that a moderate earthquake could cause over 1,000 deaths and "would have significant impact on the lives and economy of the Tri-State region." An earthquake in Manhattan? Don't Laugh!