Strong 7.1-magnitude earthquake strikes Mexico City

Earlier in the day buildings across the city held preparation drills on the anniversary of the 1985 quake

A powerful earthquake shook Mexico City today, causing panic among the megalopolis' 20 million inhabitants on the 32nd anniversary of a devastating 1985 quake.

The US Geological Survey put the quake's magnitude at 7.1 while Mexico's Seismological Institute said it measured 6.8 on its scale.

The institute said the quake's epicenter was seven kilometers west of Chiautla de Tapia, in the neighboring state of Puebla.