Report on Popocatepetl (Mexico) — October 2000
Bulletin of the Global Volcanism Network, vol. 25, no. 10 (October 2000)
Managing Editor: Richard Wunderman.
Popocatepetl (Mexico) Increased gas-and-ash emissions in early November elevates hazard status
Please cite this report as:
Global Volcanism Program, 2000. Report on Popocatepetl (Mexico) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 25:10. Smithsonian Institution.
19.023°N, 98.622°W; summit elev. 5393 m
All times are local (unless otherwise noted)
This report covers the period from 22 August to 4 November 2000 (table 13). Volcanic activity during this period generally was similar to that for the preceding summer months (BGVN 25:07). Steam-and-gas exhalations occurred frequently, with daily variations in intensity and duration. The reported number of daily exhalations varied from only a few to as many at 140 (12 September). Some exhalations included ash, several of the larger ones generated ash plumes 5 or 6 km above the crater and caused ash falls on towns downwind, including NW-flank towns. On 4 September ashfall reached the S limit of the capital. Seismic tremor was also common, both harmonic and high frequency, some of low amplitude and duration and others lasting from 30 minutes to several hours.
|Date||Exhalations||Description of other activity|
|22-23 Aug 2000||increasing||--|
|24 Aug 2000||steady||--|
|25 Aug 2000||increasing||--|
|26-27 Aug 2000||steady||--|
|28 Aug 2000||increasing||--|
|29 Aug 2000||decreasing||One VT event; harmonic tremor|
|30-31 Aug 2000||decreasing||--|
|01 Sep 2000||decreasing||--|
|02 Sep 2000||increasing||3-km-high plume; harmonic tremor|
|03 Sep 2000||decreasing||--|
|04 Sep 2000||increasing||One (M 1.8) VT event; plume; 25 minutes of harmonic tremor|
|05 Sep 2000||--||Harmonic tremor|
|06 Sep 2000||steady||Two (M less than 2) VT events; harmonic tremor|
|07 Sep 2000||steady||One (M 2.1) VT event|
|08-09 Sep 2000||steady||Harmonic tremor|
|10-12 Sep 2000||increasing||Harmonic tremor|
|13 Sep 2000||decreasing||Harmonic tremor|
|14 Sep 2000||steady||Harmonic tremor|
|15 Sep 2000||increasing||--|
|17 Sep 2000||decreasing||One (M 2.5) VT event; harmonic tremor|
|18 Sep 2000||decreasing||Harmonic tremor; 12.7 t/d SO2|
|19-21 Sep 2000||steady||--|
|22 Sep 2000||steady||One (M 2.8) VT event; 2-km-high plume|
|23 Sep 2000||decreasing||Two (M ~ 2) VT events|
|03 Oct 2000||increasing||6-km-high plume; harmonic tremor|
|04 Oct 2000||steady||1-km-high plume|
|05 Oct 2000||decreasing||--|
|06 Oct 2000||steady||Harmonic tremor|
|09-10 Oct 2000||steady||Harmonic tremor; high-frequency tremor|
|15 Oct 2000||steady||--|
|16 Oct 2000||increasing||Four (M 2.4) VT events; 2-km-high plume; explosive exhalation|
|17 Oct 2000||decreasing||High-frequency tremor|
|18 Oct 2000||increasing||3 hours of high-frequency tremor|
|19 Oct 2000||steady||High-frequency tremor|
|20 Oct 2000||increasing||--|
|21 Oct 2000||steady||Harmonic tremor; high-frequency tremor|
|22 Oct 2000||steady||Two VT events|
|23 Oct 2000||increasing||SO2 emission|
|24 Oct 2000||steady||Harmonic tremor; high-frequency tremor|
|25 Oct 2000||steady||High-frequency tremor|
|26 Oct 2000||increasing||--|
|27 Oct 2000||increasing||High-frequency tremor|
|28 Oct 2000||steady||2-km-high plume; 90 minutes of high-frequency tremor; decreased SO2 emission|
|29 Oct 2000||increasing||3-km-high plume|
|30 Oct 2000||steady||--|
|31 Oct 2000||decreasing||--|
|01 Nov 2000||steady||Harmonic tremor; high-frequency tremor|
|02 Nov 2000||--||One (M 3.1) VT event; 3-km-high plume; 30 minutes of high-frequency tremor|
|03 Nov 2000||--||Four (M 2.2-3.0) VT events; plume; Alert level raised|
Volcano-tectonic (VT) earthquakes registered on 29 August; 4, 6, 7, 17, 22, 23, September; 16, 22, 27 October; and 2, 3 November. Most of these were M <=2.0 but those occurring on 22 September, 16 October, and in early November were M 2.4-3.1. The latter two periods also coincided with explosive exhalations as described below.
On 16 September, a small dome (very small compared to the one that grew in 1997) was observed during a flight over the crater. On 18 September, an SO2 level of 12,700 tons/day was registered. The VT event on 22 September was registered 20 km SE of the volcano. An explosive exhalation at 0520 on 16 October sent incandescent fragments ~1 km to the NE. As noted above, four VT earthquakes preceded this exhalation, one (the largest) was M 2.4. A second explosive exhalation occurred later that day at 1142 although no incandescent fragments were confirmed.
On 29 October, 102 exhalations registered and, at 1710, a moderately large exhalation produced an ash plume that rose to 3 km above the crater and moved ~25 km WNW. On 2 November, the volcano had an increase in activity and at 1717 there was a moderate exhalation followed by 30 minutes of high-frequency tremor. The event sent an ash plume 3 km above the crater; ash fell on several towns. At 1827 a VT event of M 3.1 was registered SE of the volcano. Then, between 1300 and 1630 on 3 November, four VT events occurred; these M 2.2-3.0 events were located below the crater. Later that day, the Scientific Committee discussed the increased activity over the previous few days and, in conjunction with the Civil Protection Authorities, decided to change the hazard status to Yellow III, recommending further that the security radius around the volcano be increased to 10 km (from the radius of 7 km that had prevailed for many months).
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: Centro Nacional de Prevencion de Desastres (CENAPRED), Delfin Madrigal 665, Col. Pedregal de Santo Domingo, Coyoacán, 04360, México D.F. (URL: https://www.gob.mx/cenapred/); Washington VAAC, Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Road, Camp Springs, MD 20746, USA (URL: http://www.ssd.noaa.gov/).