CENAPRED reported that during 1-7 April the seismic network at Popocatépetl recorded 101-191 daily emissions except during 3-4 and 6-7 April when only 37 and 53 were detected, respectively. Cloud cover often prevented observations of the crater, although ash plumes and nighttime crater incandescence were often noted. On 3 April multiple ash plumes rose 1-3 km above the crater. A period of harmonic tremor, that began at 1039 and ended at 1338, was accompanied by continuous emissions of steam with small amounts of ash. During 3-4 April explosions generated ash plumes that rose as high as 2 km; ashfall was reported in Tetela and Ocuituco. More explosions on 4 April generated ash plumes that rose 0.5-2 km and drifted SW. During 4-6 April explosions ejected incandescent tephra 100-700 m onto the flanks, and produced steam, gas, and ash plumes that rose 1.2-2 km and sometimes drifted W. Episodes of tremor were detected on 5 April. At 0754 on 7 April an episode of explosions and tremor began. Steam, gas, and ash plumes rose from the crater and material was ejected short distances from the crater. The Alert Level remained at 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)