A strong earthquake has struck western Mexico, causing tall buildings to sway more than 200 miles away in Mexico City.

People evacuated some buildings in the capital, but the city government said helicopter flights detected no signs of damage.

The quake was centered in a sparsely populated mountain area, in Michoacan state, and there were no reports of damage there, either.

The U.S. Geological Survey initially reported a preliminary reading of 7.0 magnitude for the quake, but later downgraded it to 6.5.

A quake of that magnitude is capable of producing severe damage in an urban area, but this one occurred about 41 miles below the surface and a tremor's power to cause damage is often dissipated when it is so deep.

Wednesday's tremor was the latest in a series of strong shakes to hit Mexico City since a powerful 7.4-magnitude quake hit southern Mexico three weeks ago. That quake damaged hundreds of homes, killed at least two people and was followed by close to 400 aftershocks.

But the USGS says this latest quake was not an aftershock.


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