What Would Happen if an 8.9 Quake Hit the US?
A few days ago, driven by equal parts neuroses and scientific curiosity, I downloaded an app on my phone that tells me about recent earthquakes around the world. Over the past few days, I’ve noticed a bunch of small quakes off the eastern coast of Japan’s Honshu island, exactly where the devastating 8.9 quake struck early Friday morning, leaving hundreds dead and tens of thousands missing. I began to wonder: If I knew about the smaller quakes, then certainly seismologists must have, so why didn’t anyone warn Japan? According to Morgan Moschetti, a research geophysicist at the United States Geological Survey, clusters of small earthquakes are extremely common, and “rarely do they have any predictive value.” In this case, the earlier small quakes were what’s known as foreshocks, previews to a larger event. But there’s no way to distinguish a foreshock from a self-contained cluster. Here are some answers to a few other earthquake questions: