CENAPRED reported that during an overflight of Popocatépetl on 18 February volcanologists noted no significant morphological changes at the summit crater; the inner crater was 350 m in diameter and 100-150 m deep, and the crater floor was covered with tephra. Each day during 18-25 February there were 130-263 steam-and-gas emissions from the summit crater. As many as nine low- to moderate-level explosions were recorded each day, generating gas plumes with minor amounts of ash that drifted N, NW, and SW. An explosion at 1737 on 19 February produced an ash plume that rose 1.2 km above the crater rim and drifted NW, and ejected incandescent material onto the flanks. 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)