Report on Popocatepetl (Mexico) — September 1998
Bulletin of the Global Volcanism Network, vol. 23, no. 9 (September 1998)
Managing Editor: Richard Wunderman.
Popocatepetl (Mexico) Several episodes of ash emission during September
Please cite this report as:
Global Volcanism Program, 1998. Report on Popocatepetl (Mexico) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 23:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199809-341090.
19.023°N, 98.622°W; summit elev. 5393 m
All times are local (unless otherwise noted)
Following a large ash exhalation on 8 September (BGVN 23:08), eruptive activity at Popocatépetl decreased in intensity and duration. CENEPRED reported a few moderate emissions during September that caused local ashfall.
Small-volume, discrete, short-duration emissions containing ash, sometimes accompanied by steam and gas, were recorded occasionally during the period 9-15 September. Brief episodes of harmonic tremor were also recorded. During the night of 14 September glow reflected from clouds over the crater was seen.
Moderate exhalations of steam, gas, and light ash took place during 16 September. Several brief episodes of high-frequency tremor were recorded that afternoon; the largest emissions occurred at 1546-1552, 1604, and 1611. Ashfall was reported at Amecameca, 20 km NW of the volcano. Despite bad weather that reduced visibility most of the day, a dense column of steam and gas was seen rising 700 m above the summit before being blown to the NW. Activity decreased to stable background levels on 17 September. A dense steam and gas cloud seen on the morning of 18 September dispersed to the NE; as the cloud gained altitude, its direction changed to the south. SO2 measurements showed significant increases following the 16 September explosion over levels earlier in the month.
Another moderate increase in eruptive activity began a few days later. A steam and gas column rising 1 km above the summit was observed during 20 September. Brief, moderately intense emissions of steam and gas, sometimes with light ash puffs, took place throughout the morning of 21 September. An explosion at 1148 that morning produced light ashfall in towns up to 20 km NW of Popocatépetl. A similar but less intense event occurred at 1543. Emissions decreased to relatively low levels until 1225 on 22 September when a moderate explosion lasting 7 minutes produced a steam, gas, and ash plume that rose 4 km above the summit. Visibility during 22 August was poor due to bad weather, but a large ash cloud near the crater was detected by Doppler radar. Ash was dispersed during the afternoon NW of the volcano, producing light ash falls in the suburban SE of metropolitan México City.
Following the explosion on 22 September, eruptive activity paused until a similar explosion occurred at 1829 on 23 September. This explosion lasted 6 minutes and produced a 3-km high column of steam, gas, and ash. Ash fall was reported in towns SW of the volcano. Eruptive activity soon decreased again, stabilizing at low levels of small, isolated emissions of steam and gas, typical of earlier in September. An exhalation at 1025 on 24 September was followed by 30 minutes of low-frequency harmonic tremor. An A-type earthquake of M 2.1 located 1.8 km E of the crater at a depth of 3.9 km was recorded at 2224 on 24 September, and another moderate exhalation lasting 7 minutes began at 2332.
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.
Information Contacts: Servando De la Cruz-Reyna1,2 Roberto Quaas1,2 Carlos Valdés G.2 and Alicia Martinez Bringas1; 1 Centro Nacional de Prevencion de Desastres (CENAPRED) Delfin Madrigal 665, Col. Pedregal de Santo Domingo, Coyoacan, 04360, México D.F. (URL: https://www.gob.mx/cenapred/); and 2 Instituto de Geofisico, UNAM, Coyoacán 04510, México D.F., México.