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C. New Insight into What Triggers Deep Earthquakes

Narrator: This is Science Today. In August of 2002 two massive deep earthquakes, centered in the same underwater trench below the Fiji Islands in the Pacific, occurred seven minutes apart. Geologist Harry Green of the University of California, Riverside, says the observation that one earthquake, measuring 7.6 on the Richter Scale, caused another 7.7 quake nearby, may have major implications for understanding how earthquakes are initiated.

Green: The effects of the first earthquake 300 km away and 65 km deeper is really very, very small and that's what causes the great interest-because how could this very small effect, within seven minutes, produce an earthquake even larger than the one that triggered it?

Narrator: Green says this event may help us understand the physical mechanism that causes earthquakes, so that we can better predict damaging quakes in the future - even ones at more shallow depths.

Green: It gives us a new time element to combine with seismology that can give us insight as to how the earthquakes get started.

Narrator: For Science Today, I'm Larissa Branin.