6.4 earthquake shakes Mexican capital
A strong earthquake has struck Mexico's capital.
There is no immediate word of damage or casualties.
The U.S. Geological Survey says a magnitude 6.4 earthquake hit Mexico just north-west of San Marcos.
Mexico City is vulnerable even to distant earthquakes because much of it sits atop the muddy sediments of drained lake beds that quiver as quake waves hit.
The magnitude-8.1 quake in 1985 that killed at least 6,000 people and destroyed many buildings in Mexico City was centered 250 miles (400 kilometers) away on the Pacific Coast.