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Photos Where the Faults Are
As for why McCaffrey's model came up with fewer magnitude 9 quakes than have been seen in the last 50 years, that's just a matter of the sample size, he said. "One of the analogies is that you go into a friend's house and their baby is crying the entire ten minutes you are there," McCaffrey explains. You leave with the impression that the baby cries all the time. However, it might also be that you just happened in during the baby's only fit all day. The same goes for watching really big, rare earthquakes. "We've been just watching this process that has thousands of years in a cycle," said McCaffrey. Yet the seismograph was only invented about 100 years ago, and historical records noting magnitude 9 earthquakes only extend back about 300 years, at best. So whatever patterns we see are not likely to represent a long-term average. "His argument is, anywhere you have a subduction zone you can't exclude the possibility," said seismologist Seth Stein of Northwestern University. "What that means is when you think of giant ocean tsunamis, you can't count on where they will come from." In other words, said Stein, McCaffrey's paper is bad news for tsunami emergency planners because it increases the number of disaster possibilities. Related Links: |
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