Located 60 km SE of Mexico City, frequent historical eruptions have been reported from Popocatépetl going back to the 14th century. Activity increased in the mid-1990s after about 50 years of quiescence, and the current eruption, which has been ongoing since January 2005, has included frequent ash plumes and numerous episodes of lava-dome growth and destruction within the 500-m-wide summit caldera. Multiple emissions of steam and gas occur daily, rising generally 1-4 km above the 5.4-km-elevation summit; many contain small amounts of ash. Larger, more explosive events that generate ashfall in neighboring communities often occur every week.

Activity through July 2017 was typical of the ongoing eruption with near-constant emissions of water vapor, gas, and minor ash, as well as multiple explosions every week with ash-plumes and incandescent blocks sent down the flanks (BGVN 42:09). This report covers similar activity through February 2018. Information about Popocatépetl comes from daily reports provided by México's Centro Nacional de Prevención de Desastres (CENAPRED); ash emissions are also reported by the Washington Volcanic Ash Advisory Center (VAAC). Satellite visible and thermal imagery and SO₂ data also provide important observations.

Near-constant emissions of steam and gas, often with minor ash content, were typical activity for throughout August 2017-February 2018. Intermittent larger explosions with plumes of moderate ash content that generated ashfall in nearby communities were reported in most months, including several times during October and November 2017, reaching communities as far as 70 km away. Incandescence at the summit was often observed on clear nights, and Strombolian activity that sent incandescent blocks several hundred meters down the flanks occurred at least once each month during September 2017-January 2018. The tallest ash plumes during the period reached 9.1 km altitude in mid-October and 10.3 km altitude at the end of January 2018. Thermal anomalies were persistently detected in satellite data throughout the period, and SO₂ plumes were recorded every month with satellite instruments.

Activity during August-September 2017. The Washington VAAC reported satellite observations of an ash plume extending 55 km W of the summit at 6.4 km altitude on 31 July 2017; the plume was mostly gas and steam with a small amount of ash. CENAPRED reported ashfall in Ozumba (18 km W) on 1 August from a plume that rose 2 km above the summit. They also noted numerous low-intensity explosions with steam, gas, and ash during 5-7 August. A small explosion early on 14 August produced a 500-m-high plume with minor ash content that drifted SW. Two explosions later in the day generated ash plumes that rose 0.8 and 1.5 km from the summit and drifted W (figure 94). Another explosion on 15 August produced a plume over 1 km in height with moderate ash content. On 21 August CENAPRED reported an ash plume that rose 4 km and drifted NW (figure 95). The Washington VAAC reported this plume extending 33 km W from the summit at 7.6 km altitude. Later in the day the ash cloud was observed about 230 km W of the summit, and a new cloud at a slightly lower altitude had drifted 45 km NW.

Figure 94. An ash plume drifted W from Popocatépetl on 14 August 2017 as seen from the Tlamacas webcam located about 5 km N of the volcano. Courtesy of CENAPRED.

Figure 95. An ash plume at Popocatépetl rose 4 km above the summit on 21 August 2017 and drifted over 200 km W before dissipating. View is from the Altzomoni webcam, located about 10 km N of the summit. Courtesy of CENAPRED.

CENAPRED noted 22 explosions with ash during 25-26 August that drifted N and NW. They were observed in satellite imagery by the Washington VAAC at 7.6 km altitude. Eleven explosions with small amounts of ash were reported by CENAPRED on 27 August. There were daily explosions during 28-31 August, but weather clouds obscured views of the summit. Incandescence at the summit crater was observed on many clear nights during August.

During 1-11 September 2017 cloudy conditions generally prohibited observations of the summit, but low-intensity emissions of steam and gas were briefly observed, many containing minor ash. Five explosions with minor ash emissions were reported by CENAPRED on 12 September; the Washington VAAC noted the ash plume in satellite imagery at 6.7 km altitude drifting slowly N. CENAPRED reported 22 explosions with ash and incandescent rocks on the NE flank during 12-13 September.

The Washington VAAC reported ash plumes on 13 September at 8.2 km altitude, on 18 September at 6.4 km altitude drifting W, and on 23 September near 7 km altitude moving to the NNE. Numerous explosions were reported by CENAPRED during 27 and 28 September (figure 96). The Washington VAAC reported the dense ash plume from these explosions at 6.7 km altitude drifting WSW. It extended 130 km W of the volcano by early afternoon on 27 September. CENAPRED reported that an explosion late on 30 September sent incandescent fragments 0.8 km from the crater and produced a dense ash column that rose more than 2 km above the summit.

Figure 96. A dense ash emission from Popocatépetl on 27 September 2017 extended 130 km W before dissipating as viewed from the Altzomoni webcam, located about 10 km N of the summit. Courtesy of CENAPRED.

Activity during October-November 2017. The ash plume from the explosion late on 30 September 2017 was visible in satellite imagery the following morning located 15 km SW from the summit at 7.9 km altitude according to the Washington VAAC. CENAPRED reported three explosions on 2 October and five explosions the next day, causing ashfall in Atlautla (17 km W), Tepetlixpa (21 km W), and Ozumba. Three explosions on 5 October resulted in ashfall in Totolapan (32 km W), Tlalnepantla (40 km W), and Cuernavaca (64 km W), and closer to the volcano in Ecatzingo (15 km SW), Atlautla, and Tepetlixpa. Lahars were also observed on the W flank, but there were no reports of damage. Two more explosions on 6 October led to ashfall reported from Zacualpan de Amilpas (30 km SW) and Tetela del volcán (18 km SW) (figure 97). The Washington VAAC reported the 6 October emissions at 6.4 km altitude.

Figure 97. Webcam image showing one of the two explosions on 6 October 2017 at Popocatépetl that caused ashfall in Zacualpan de Amilpas (30 km SW) and Tetela del volcán (18 km SW). The Tlamacas webcam is located about 5 km N of the volcano. Courtesy of CENAPRED.

The first of two explosions on 7 October 2017, shortly after midnight, produced a plume that rose over 2 km and drifted SW with ashfall reported in Tetela del volcán; incandescent blocks were also sent down the flanks (figure 98). The second explosion produced an ash plume that rose 3 km and drifted NNE. The Washington VAAC reported continuing ash emissions during 7-11 October. Numerous plumes rose to 5.8-9.1 km altitude and drifted in several different directions; the plume extended 130 km SW from the summit on 10 October. CENAPRED reported three explosions on 8 October (figure 99) and two on 9 October. Numerous low-intensity exhalative events during 10-12 October produced ash plumes less than 1 km above the crater that drifted SW. Ashfall was reported in several communities during this time including Ozumba, México City (60 km NW), Milpa Alta (45 km NW), Xochimilco (56 km NW), Tlalpan (68 km NW), Coyoacán (66 km NW), Iztapalapa (57 km NW), Magdalena Contreras (72 km NW), and Iztacalco (64 km NW).

Figure 98. Incandescent blocks visible in this image traveled down the flanks of Popocatépetl during the early morning of 7 October 2017. The Tlamacas webcam is located about 5 km N of the volcano. Courtesy of CENAPRED.

Figure 99. Multiple explosions from Popocatépetl on 8 October 2017, including the one seen here, caused ashfall in several communities NW of the volcano. The Tlamacas webcam is located about 5 km N of the volcano. Courtesy of CENAPRED.

CENAPRED noted incandescence at the crater during most nights from 14 to 31 October, as well as steam, gas, and minor ash from hundreds of low-intensity emission events each day. The Washington VAAC reported ash emissions visible in satellite imagery on 16, 20-22, and 26 October drifting in several different directions at altitudes of 5.8-7.6 km. The plume observed on 22 October reached 60 km from the summit before dissipating. CENAPRED reported two explosions with ash plumes each day during 25-27 October. The Washington VAAC reported an ash plume on 29 October at 6.1 km altitude drifting E about 35 km from the summit, and another at 6.7 km the following day along with an infrared hotspot visible at the summit.

The Washington VAAC issued multiple daily ash advisories throughout November 2017. CENAPRED reported hundreds of daily low intensity emissions of gas and steam that often contained minor ash; the plumes generally rose about 1 km above the summit and most often drifted SW. They also observed incandescence at the crater on all clear nights. They reported Strombolian activity on 3 November in the early morning that lasted for several hours. Explosions early on 4 November resulted in minor ashfall in Yecapixtla (29 km SW) and Zacualpan de Amilpas and other areas to the SW. A Strombolian episode later that day lasted for about an hour and resulted in minor ashfall in Tetela del Volcán. Another explosion that night sent incandescent fragments 200 m down the flanks.

An explosion on 6 November sent an ash plume 2.5 km above the summit crater that drifted SW and sent incandescent fragments 500 m down the flank. Another explosion during the early morning of 7 November produced a 2-km-high ash plume. Moderate amounts of ash rose 1 km above the summit on 8 November. There were three explosions on 10 November; the largest produced a 3-km-high ash plume that drifted SW. Continuous low-level emission of gas and ash on 14 November resulted in ashfall reported in Totolapan, Yecapixtla, Ocuituco (23 km SW), Tetela del Volcán, and Ecatzingo. An explosion on 17 November sent an ash plume 2.5 km above the summit that drifted SW. During 18-19 November five explosions caused ash plumes to rise 2 km above the summit and incandescent blocks to fall down the E flank.

Around 1030 on 20 November, seismic activity increased and was accompanied by a constant plume of steam, gas, and moderate ash that rose about 1.5 km and drifted E. During 20-21 November eight explosions were reported, with five more the following day. During the afternoon of 23 November a continuous ash emission that lasted 90 minutes drifted SSE at 2 km above the summit, and spread ash over communities to the SSE including Huaquechula (30 km SSE), Tepeojuma (38 km SE), Atlixco (23 km SE), and Izúcar de Matamoros (50 km SE) (figure 100). Another significant ash emission during the afternoon of 24 November sent a column of ash to 4 km above the summit, drifting SSE; it lasted for almost two hours (figure 101). The Washington VAAC reported the plume at 8.5 km altitude. Ashfall was reported in San Pedro Benito Juárez (12 km SE) and Atlixco. Late that evening, an explosion sent incandescent fragments 1 km down the flanks and generated an ash plume that rose to 2.5 km above the summit and also drifted SSE.

Figure 100. A continuous ash emission at Popocatépetl that lasted for 90 minutes drifted SSE at 2 km above the summit, and spread ash over several communities to the SSE on 23 November 2017. The Tlamacas webcam is located about 5 km N of the volcano. Courtesy of CENAPRED.

Figure 101. A substantial ash emission at Popocatépetl during the afternoon of 24 November 2017 sent a column of ash to 4 km above the summit that drifted SSE; it lasted for almost two hours. The Washington VAAC reported the plume at 8.5 km altitude. The Altzomoni webcam is located about 10 km N of the summit. Courtesy of CENAPRED.

A flyover by CENAPRED and the Federal Police on 25 November 2017 allowed evaluation of the changes in the summit crater from the recent explosions. They noted that the internal crater within the summit crater had increased its dimensions, reaching a diameter of 370 m and a depth of 110 m (figure 102). A 3-km-tall ash plume resulted from continuous emissions that began in the afternoon of 27 November and lasted for two hours. The Washington VAAC reported the plume at 7.9 km altitude. The plume drifted SSE, and dispersed ash over communities in that region including Tochimilco (16 km), Izucar de Matamoros, Atlixco, and Huaquechula.

Figure 102. During a flyover on 25 November 2017, CENAPRED observed that the increased size of the internal summit crater at Popocatépetl was 370 m in diameter and 110 m deep. Courtesy of CENAPRED.

Activity during December 2017-February 2018. The Washington VAAC issued multiple daily reports of ash emissions during 1-12 and 24-31 December 2017. CENAPRED noted hundreds of daily low-intensity emissions of gas and steam, most with small quantities of ash, throughout December, as well as multiple ash emissions on many days that rose generally 1-2.5 km above the summit. In the early morning of 2 December an explosion caused an ash plume to rise 2.5 km above the summit. A second plume rose 1 km later that day; they both drifted SSE. An explosion in the afternoon of 9 December sent an ash plume over 2.5 km above the summit that drifted NE. The Washington VAAC reported the plume at 7.6 km altitude. Later that evening Strombolian activity sent incandescent blocks down the flanks and generated an ash plume that drifted E. Incandescence was observed at the summit crater during the nights of 17-21 and 24-29 December. Continuous emissions of steam, gas, and moderate-density ash were reported drifting NW for about 90 minutes on 29 December. An explosion on 31 December at 1032 generated a 2-km-high ash plume that also drifted NW.

There were multiple daily reports of ash emissions issued by the Washington VAAC during most days of January 2018. CENAPRED noted hundreds of daily low-intensity emissions of gas and steam, many with small quantities of ash, throughout the month, as well as explosions with ash emissions on many days that generally rose 1-2.5 km above the summit. They also observed incandescence at the summit crater multiple days each week. Ongoing low-level emissions of steam, gas, and minor ash were reported during 4-5 January. During the evening of 5 January activity increased, and the ash plume rose to 800 m and drifted SE. In addition, incandescent blocks were ejected 200-300 m down the flanks for about two hours.

An explosion on 18 January 2018 generated an ash plume that rose 1.5 km above the summit and drifted E while incandescent blocks were ejected up to 700 m down the flanks. An episode of Strombolian activity in the early morning of 25 January produced an ash plume that rose 2 km above the summit and drifted N and NE, resulting in reports of ashfall in San Pedro Nexapa (14 km NE) and Amecameca (19 km NE). It lasted for about 2 hours. Four explosions were reported during the afternoon of 29 January and an explosion the following afternoon produced an ash plume that rose more than 3 km above the summit, and was dispersed to the NW. An explosion on 31 January also produced a substantial ash plume that the Washington VAAC reported at 10.3 km altitude moving NNE (figure 103).

Figure 103. An ash plume rose to 10.3 km altitude from Popocatépetl on 31 January 2018 and drifted NNE. The Altzomoni webcam is located about 10 km N of the summit. Courtesy of CENAPRED.

Activity was somewhat quieter at Popocatépetl during February 2018. The Washington VAAC reported ash emissions on 14 days during the month. CENAPRED reported tens, not hundreds, of daily low-intensity emissions of gas and steam that often contained minor amounts of ash. They also noted one or more explosions with ash emissions on many days that rose generally 1-1.5 km above the summit and drifted in various directions. During many clear days they observed nearly constant emissions of steam, gas, and minor ash that reached 500-800 m above the summit. An explosion on 20 February produced an ash plume that rose 1.5 km above the summit. Continuous steam and gas emissions during 22-23 February were accompanied by minor incandescence intermittently observed at the summit.

Satellite data. Sulfur dioxide emissions were large enough to be recorded by satellite instruments several times every month during August 2017-February 2018 (figure 104). Variable wind directions and persistent emissions produced relatively long-lived plumes that dispersed over large areas of Mexico.

Figure 104. The OMI instrument on NASA's AURA satellite recorded evidence of significant monthly SO2 emissions at Popocatépetl, including on 27 September 2017 (upper left), 13 October 2017 (upper right), 31 October 2017 (lower left) and 25 December 2017 (lower right). Variable wind directions and persistent emissions produced relatively long-lived plumes that dispersed over large areas of Mexico. Courtesy of NASA Goddard Space Flight Center.

Thermal anomaly data provided by the MIROVA project are consistent with the visual record of persistent incandescent and explosive activity at the summit (figure 105). Multiple MODVOLC thermal alerts were also recorded every month from October 2017-February 2018.

Figure 105. Thermal anomalies detected by satellite-based MODIS instruments and recorded through the MIROVA project show the pattern of continued moderate-level activity at Popocatépetl during the year ending 12 July 2018. Courtesy of MIROVA.

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: http://www.cenapred.unam.mx/), Daily Report Archive http://www.cenapred.unam.mx:8080/reportesVolcanGobMX/BuscarReportesVolcan); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); 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/); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).