Earth’s Moving Mantle Leads To Earthquakes In Unusual Places

It has long been a mystery why some earthquakes strike towns in seemingly earthquake-proof regions, but researchers now have a potential explanation for why temblors sometimes rattle where they’re not expected. Understanding the underlying source of these quakes could help officials prepare for their associated hazards. Researchers found that intraplate earthquakes — which occur in the middle, instead of at the borders, of tectonic plates — are influenced by convection, or heat-driven movements, of the molten mantle beneath the planet’s cold, solid crust. Although intraplate quakes make up a small percentage of overall earthquakes (98 percent of earthquakes occur at the boundaries of tectonic plates), they have been recorded at strengths of up to magnitude 7.0 and can be among the most disastrous temblors because they’re unexpected, said Thorsten Becker, lead author of the new study and a professor of earth sciences at the University of Southern California. For one, towns hit by intraplate earthquakes are less likely to have earthquake-prepared infrastructure than towns that sit on plate boundaries, he said.

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