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Report on Pacaya (Guatemala) — December 2009

Bulletin of the Global Volcanism Network, vol. 34, no. 12 (December 2009)
Managing Editor: Richard Wunderman.

Pacaya (Guatemala) Variable activity in 2009 and early 2010

Please cite this report as:

Global Volcanism Program, 2009. Report on Pacaya (Guatemala). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 34:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200912-342110.

Volcano Profile |  Complete Bulletin


Pacaya

Guatemala

14.382°N, 90.601°W; summit elev. 2569 m

All times are local (unless otherwise noted)


Our last report on Pacaya was in August 2008 (BGVN 33:08), which covered activity through September 2008. Unless otherwise indicated, the following report is a compilation of reports from Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH).

During 8-14 October 2008, the pattern of previous activity continued with multiple lava flows on the W and SW flanks of MacKenney cone that traveled a maximum distance of 250 m and continued to fill in the area between the cone and Cerro Chino crater to the N. Avalanches occurred from the lava-flow fronts on 8 October. Fumarolic plumes drifted SW.

Based on analysis of satellite imagery, the Washington VAAC reported that on 2 November 2008 a possible ash-and-gas plume was emitted from Pacaya and drifted E. On 3 November, INSIVUMEH reported that fumarolic plumes drifted S at a low altitude. Ash occasionally entrained by strong winds drifted S. Multiple lava flows on the S and SW flanks of MacKenney cone traveled a maximum distance of 400 m on 3 and 4 November, and continued to fill in the area between the cone and Cerro Chino crater to the N. Fumarolic plumes drifted E on 4 November. On 20 November fumarolic plumes from Pacaya's MacKenney cone drifted S at a low altitude. Ash occasionally entrained by strong winds drifted S. Multiple lava flows on the S, W, and SW flanks of the cone traveled 50-300 m during 20-21 and 25 November.

On 12 December 2008 fumarolic plumes from Pacaya's MacKenney cone drifted NE at a low altitude. Three lava flows, 150, 250, and 800 m long, were observed from the S. Seismic data indicated small explosions at the crater.

On 30 January and 3 February 2009, white and blue fumarolic plumes from MacKenney cone drifted S and SW at a low altitude. One lava flow, 75-100 m long, traveled down the SW flank.

On 12, 16, and 17 March 2009, fumarolic plumes from MacKenney cone drifted S at a low altitude. Lava flows, 25-200 m long, traveled S, SW, and W. Explosions during March ejected greater amounts of material that was deposited in the crater, enlarging the cones there. On 23 March, visual and audible changes in Strombolian activity were noted. Vigorous degassing produced sounds resembled airplane engines.

In a report issued on 3 April 2009, INSIVUMEH stated that Strombolian explosions from MacKenney cone during the previous few days ejected material 25 m into the air. On 2 April, lava flow volume increased, sending four lava flows W and one SW; the flows traveled 25-200 m. The seismic network detected tremor and explosions. On 6 April, lava flows on the W flank traveled 150-300 m, causing lava to collect on the SW flank. Activity from MacKenney cone was continuous; one cone emitted gas and explosions about every 5-10 minutes, and a second cone ejected tephra 25 m high. On 7 April, one lava flow traveled 150 m W and one traveled 200 m SW. INSIVUMEH recommended that CONRED coordinate with authorities in Pacaya National Park to restrict visitors from climbing Pacaya. On 24 and 28 April, INSIVUMEH reported gas emissions from Pacaya's MacKenney cone; occasional ash explosions ejected tephra 15-25 m high. The seismic network detected tremor and explosions. A small spatter cone being built in the S part of the crater was 4 m high. Rumbling noises were heard 3-5 km away and degassing produced sounds resembling airplane engines. Lava flows traveled 50-400 m down the SW flank and fumarolic plumes drifted S. This pattern of activity continued throughout May 2009.

For the remainder of 2009, the pattern remained much the same. On 5, 8, and 9 June 2009, white and blue fumarolic plumes from Pacaya's MacKenney cone rose to as high as 400 m and drifted, S, W and SW. Multiple lava flows up to 600 m long, were emitted from an area on the lower S flank, SW from the main edifice and traveled S, SW and W. Incandescence at night was noted on 20 November and 18 December.

Similar activity continued in 2010. On 8, 11, and 12 January 2010, white and blue fumarolic plumes from Pacaya's MacKenney cone rose up 400 m and drifted S and SW. Multiple lava flows on the S, SW, and W flanks traveled 25-200 m. Incandescence was noted at night from one of the inter-crater cones on 8 January and from MacKenney cone on 11 and 12 January.

Geologic Background. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.

Information Contacts: Gustavo Chigna, Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hydrologia (INSIVUMEH), 7a Avenida 14-57, Zona 13, Guatemala City, Guatemala (URL: http://www.insivumeh.gob.gt/); Washington Volcanic Ash Advisory Center (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.ospo.noaa.gov/Products/atmosphere/vaac/).