Centro Nacional de Prevención de Desastres (CENAPRED) reported that eruptive activity continued at Popocatépetl during 24 September-1 October. Weather clouds sometimes prevented visual observations. The seismic network recorded 9-58 long-period events per day that were accompanied by steam-and-gas emissions; emissions contained minor amounts of ash during 29-30 September. The seismic network also recorded daily tremor with periods lasting from 57 minutes up to five hours and nine minutes, and a period of emissions that lasted 18 minutes during 27-28 September. According to the Washington VAAC ash plumes visible in webcam and satellite images on 28 September rose to 6.7 km (22,000 ft) a.s.l. (or about 1.3 km above the crater rim) and drifted NW and NE. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay 12 km away from the crater.

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.

Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC)