Updated

An earthquake is shaking Mexico's capital.

There is no immediate word of damage or casualties and seismologists have not yet issued a calculation of its power or epicenter.

Mexico City is vulnerable to distant earthquakes because much of it sits atop the muddy sediments of drained lake beds. They jiggle like jelly when 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.