MEXICO -- Central Mexico's major volcano, which is nicknamed Popo, erupted again Tuesday night, sending lava, ash and smoke 2 miles into the air.No injuries have been reported, but Mexican authorities warned nearby residents to stay inside for the time being.The Popocatepetl volcano has been dormant for almost 50 years. Popo came back to life in 1994 and has produced powerful explosions irregularly ever since.Tuesday's explosion has not affected flights in and out of Mexico City.