Centro Nacional de Prevención de Desastres (CENAPRED) reported that eruptive activity continued at Popocatépetl during 10-16 July. Daily activity consisted of 5-22 long-period (LP) events that were accompanied by emissions of gas, steam, and small quantities of ash. Additionally, volcano-tectonic (VT) earthquakes were registered on 11, 12, and 16 July. The most significant VT earthquake was a M1.9 that occurred at 0905 on 16 July. Continuous gas-and-steam emissions were observed on some mornings; plumes dispersed towards the WSW and WNW. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay at least 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.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)