Popocatépetl continued to be active during September 2010 to 13 December 2011 with explosions, tremor, and frequent gas-and-steam emissions occasionally containing ash (figure 59). This report continues the table in the previous report (BGVN 35:08) that tallies the seismic activity and ash emissions (table 21). Figure 60 shows the proximity of the volcano to population centers.

Figure 59. Photograph of the lava dome at Popocatépetl taken on 8 September 2011. Courtesy of CENAPRED.

Table 21. Reported plumes above Popocatépetl's summit crater that contained some ash between 5 October 2010 and 13 December 2011. Data provided by the MWO (Mexico City Meteorological Watch Office), Washington Volcanic Ash Advisory Center (VAAC), and Centro Nacional de Prevención de Desastres (CENAPRED), abbreviated CEN.

Figure 60. Map of Popocatépetl in relation to Mexico City and other large communities. Circular areas are approximate; they show some hazard zones, including the innermost "Red" zone, which is within 5 km of the summit and excludes the public from entry. Courtesy of CENAPRED.

During the reporting interval, there were a large number of MODVOLC thermal alerts for Popocatépetl.

Arana-Salinas and others (2010) discuss the Ochre Pumice Sequence, a major (VEI 6) event that occurred ~ 5,000 years ago. That unit contained a sequence of pyroclastic flow and fall deposits that covered ~ 300 km² directed NNE. The erupted magma amounts to a (dense rock equivalent) volume of ~2 km³. The authors stated that, depending on the wind direction, an equivalent event today would impact 15 million residents of Mexico City (the Capital), Puebla, Atlixco, and Cuautla and elsewhere, and it would severely damage infrastructure.

Reference. Arana-Salinas, L., Siebe, C., Macías, J.L, 2010, Dynamics of the ca. 4,965 yr ¹⁴C BP "Ochre Pumice" Plinian eruption of Popocatépetl volcano, México: Journal of Volcanology and Geothermal Research v. 192. p. 212-231.

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.

Information Contacts: Centro Nacional de Prevención de Desastres (CENAPRED), Av. Delfín Madrigal No.665. Coyoacan, México D.F. 04360, México (URL: https://www.gob.mx/cenapred/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/); MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).