More than 25 million people live in the vicinity of Mt. Popocatepetl, including Mexico City’s 18 million residents. At 2:32 local time on Tuesday morning, the most dangerous volcano in Mexico roared to life in spectacular fashion, and this has many expertsextremely concerned about what is coming next. Popocatepetl is an Aztec word that means “smoking mountain”, and historians tell us that once upon a time entire Aztec cities were buried in super-heated mud from this volcano. In fact, the super-heated mud flows were so deep that they buried entire Aztec pyramids. A full-blown eruption of Mt. Popocatepetl would be a catastrophe unlike anything that modern Mexico has ever experienced before, and considering what has been happening in Ecuador, Japan and at Yellowstone over the past week, I believe that there is great reason for concern.