Happy Monday morning. Here's a sobering image. As the two crustal plates of the Cascadia subduction zone slowly grind past each other, small earthquakes occur constantly 25 miles below the surface. We can't feel them, but every14 months or so, there’s a sharp spike in the rate of movement.
Scientists say these episodes increase the probability of a much larger earthquake. They hope that tracking these tremors might eventually help predict major earthquakes. When the “locked zone” between the plates can’t take any more, they will slip, causing a magnitude 9 + earthquake. The really big one.
As late as the 1970's, we thought earthquakes were just California's problem. Now we know our earthquakes are more infrequent, but ferocious. The geological record reveals that "great earthquakes" occur in the Cascadia subduction zone about every 500 years on average. The last one was in 1700.
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