Seismologist: Mexico's 7.1 quake not aftershock - KWWL - Eastern Iowa Breaking News, Weather, Closings

Seismologist: Mexico's 7.1 quake not aftershock

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(AP) -

The 7.1 earthquake was too far from the larger quake 11 days ago to be an aftershock and appears to be a separate and unrelated event, said U.S. Geological Survey seismologist Paul Earle. The epicenters of the two quakes are 650 kilometers apart and most aftershocks are within 100 kilometers, Earle said.

Tuesday's quake was at a known tectonic fault, but not at the edges of two moving plates, like many strong earthquakes, Earle said. This fault was inside the Cocos plate, which about 300 kilometers further east slips under the North American plate. As that happens, there is a "pulling apart motion" of the plates, he said.

There have been 19 earthquakes of magnitude 6.5 or larger within 250 kilometers of Tuesday's quake in the past century, Earle said.

Tuesday's quake happened on the anniversary of a deadly 1985 Mexico City 8.0 magnitude earthquake, Earle said.

Earth usually has about 15 to 20 earthquakes this size or larger each year, Earle said.

Initial calculations show that more than 30 million people would have felt moderate shaking from Tuesday's quake. The US Geological Survey predicts "significant casualty and damage are likely and the disaster is potentially widespread."

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