CENAPRED reported that during 15-21 May seismicity at Popocatépetl indicated continuing gas-and-steam emissions that contained variable amounts of ash; the plumes were sometimes visually confirmed although cloud cover often prevented observations. Incandescence from the crater was often observed at night.

At 0956 on 14 May an explosion generated an ash plume that rose 3 km above the crater and drifted NE, and ejected tephra onto the NE flank at a distance of 600 m. Volcanologists aboard an overflight observed a lava dome 350 m in diameter and 50 m thick, that had slightly deflated after the earlier explosion. An explosion at 0146 on 15 May again generated an ash plume that rose 3 km above the crater, and ejected incandescent tephra onto the flanks at a maximum distance of 1.5 km. At 1804 an explosion produced an ash plume that rose at least 3.5 km and drifted N.

On 16 May gas-and-ash plumes rose 2 km and drifted NE. Minor ashfall was reported in Paso de Cortés, 7 km N. Incandescent tephra was ejected onto the N and NE flanks at a maximum distance of 400 m. The ejections corresponded with several periods of high-frequency, low-amplitude tremor detected between 2020 and 2308, and a swarm that began at 0011 on 17 May. At 2214 an intense explosion ejected incandescent tephra 1.5 km from the crater, and generated an ash plume that rose over 3 km and drifted NE.

At 0028 on 17 May another strong explosion ejected incandescent tephra 1.5 km from the crater, and generated an ash plume that rose over 4 km and drifted NE. Later that day plumes of vapor and gas rose 1 km and drifted SW. During an overflight on 18 May volcanologists observed a crater 200 m wide and 40 m deep in the dome’s surface; the material was likely excavated by the explosions during 14 and 16-17 May. The rest of the dome was covered with rock fragments. Gas-and-ash plumes rose 500 m and drifted SW.

During 19-20 May gas-and-ash plumes drifted E and SW and incandescent tephra was deposited mainly on the NE flanks 400 m away, although most ejected fragments fell back inside the crater. On 21 May steam-and-gas plumes rose a few meters then drifted SSE.

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)