Measuring the Big One These days, an earthquake happens and right away you hear about it on the news, including its magnitude. Instant magnitudes seem like a routine achievement, like reporting the temperature. But that feat is the result of generations of scientific work. Earthquakes, in fact, are very hard to measure. The problem is like coming up with one number to indicate the quality of a baseball pitcher. You can start with the pitcher's win-loss record, but the more you study the problem the more things you want to consider, like earned-run average, defensive range, strikeouts and walks, career...