CENAPRED reported that each day during 5-12 May there were 94-157 steam-and-gas emissions from Popocatépetl, some of which contained minor amounts of ash. Minor explosions were recorded at 1534 and 1609 on 7 May, at 1648 on 10 May, at 1723 and 2351 on 11 May, and at 0302 and 0604 on 12 May. Crater incandescence was visible some nights. The Alert Level remained at Yellow, Phase Two (middle level on a three-color scale).

Geological Summary. Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)