The surprising threat from Mexico's awakened volcano

Minor earthquakes have recently rocked Mexico's Popocatépetl volcano and it has been giving off gas, ash, and glowing hot rocks. Experts are worried about mudflows (debris flows / lahars), that may occur when volcanic ash is mixed with water near the top of the volcano.

"Thinking about them as mud is technically accurate, but conceptually it's more like a wall of cement flowing," told Ben Andrews, a research geologist at the Smithsonian's Global Vulcanism Program to OurAmazingPlanet, "and it destroys pretty much everything in its path." According to the expert, “they're moving at tens of miles per hour."

Geologist Mike Sheridan said that "mudflows can be detected and there can be a warning of up to a half-hour in advance." Scientists warn that it is important to maintain an accurate warning system so that people heed them.