Now dangerous in Mexico

Now dangerous volcanoes around the world.

Mexico City, a metropolis of 18 million people, sits 40 miles to the east of Popocatépetl, the second tallest volcano in North America. Puebla, a town of 2 million, lies 30 miles to the west. A major eruption, scientists say, could choke the skies with ash and send massive mudslides into the crowded valleys below. The result could prove catastrophic. The volcano has been relatively quiet since a bout of activity between 1920 and 1922, though it rumbled back to life in 2000, as shown in this image, prompting evacuation orders and worries that "Popo" is ready to blow.