Report on Popocatepetl (Mexico) — 23 April-29 April 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 April-29 April 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Popocatepetl (Mexico). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 23 April-29 April 2003. Smithsonian Institution and US Geological Survey.
19.023°N, 98.622°W; summit elev. 5393 m
All times are local (unless otherwise noted)
On 24 April at 2050 Popocatépetl issued a moderate explosion that threw incandescent fragments 1.5-2.0 km above the crater and generated an ash column that rose to ~2.5 km above the crater. The plume was initially carried E. This activity was related to the destruction of a small dome that formed in the past few days. After the explosion, activity dropped to its previous more tranquil levels.
A small explosion occurred late on 26 April, followed by a clear increase in vigor on 28 April, including another moderate explosion at 0120 that day. Incandescent fragments landed on the E and NE flanks up to ~800 m from the crater. The outburst included a 40-second phase of greatest intensity. Ash falls were not reported. Hours later on 28 April instruments began to register harmonic tremor of moderate amplitude, signals that continued for 13 hours.
During the next day the eruptive vigor dropped to modest levels (only four exhalations of low intensity occurred, a smaller number than typical, and chiefly containing steam and gas rather than ash). Scientists attributed the 28 April eruption and increased eruptive vigor to advanced rates of lava ascent and extrusion. They suggested that these may have been higher than seen either earlier this year or near the end of last year. The hazard status was raised one increment, to Yellow phase 3. In addition, the highway traversing the Cortés pass was closed to traffic for two days, 29-30 April.
Geologic Background. 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.