CENAPRED reported that during 14-20 August seismicity at Popocatépetl indicated continuing emissions; cloud cover sometimes prevented observations of the crater. Incandescence from the crater was observed and occasionally intensified with some emissions. On 14 August a period of tremor was accompanied by an ash emission that drifted W. Ashfall was reported in the towns of Ozumba (18 km W), Tepetlixpa (20 km W), Atlautla (17 km W), and Ecatzingo (15 km SW) in the State of México. Later that day an ash plume rose 1 km above the crater and drifted W. Gas-and-steam plumes were observed during 15-16 August. A period of tremor on 17 August was accompanied by an ash plume that rose 1.5 km and drifted WSW. Ash fell in Tetela del Volcán (20 km SW), Ocuituco (24 km SW), Yecapixtla (31 km SW), Tlayacapan (40 km WSW), Cuautla (43 km SW), Ayala (45 km SW), and Cuernavaca (65 km WSW). On 18 August high-frequency, low-amplitude tremor was accompanied by an ash emission that rose 1.2 km and drifted SW. On 19 August minor steam-and-gas emissions drifted W. During 19-20 August emissions likely contained small amounts of ash but cloud cover prevented confirmation. The Alert Level remained at to Yellow, Phase Two.

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)