Video: Popocatepetl volcano's activity puts Mexico City on alert Residents living in the town of San Nicolas de Los Ranchos near the volcano are preparing for possible evacuations by registering with emergency service crews in the town square. "Right this moment we are on yellow alert level which is half way, within phase 3, which is the highest within the yellow alert level," Mexico's President Felipe Calderon said. The last major eruption of Popocatepetl forced thousands of people to flee their homes in 2000.