Earth:Pululahua
Pululahua is a dormant volcano in the north of Quito Canton, Pichincha Province, Ecuador. The volcano is in the Western Cordillera of the northern Ecuadorian Andes, approximately west-southwest of Mojanda and north of Casitahua volcanoes. Pululahua's caldera is approximately 5 km wide.The volcano is within an Ecuadorian national park known as Reserva Geobotánica Pululahua.
Geology
Volcanism at Pululagua is the result of subduction as the Nazca plate subducts under the South American plate. Research show that past eruptions were large and violent, with the last eruption taking place in 290 CE. Past eruptions have deposited ash between 10 and 1000 m thick.[1]
In 467 BCE, Pululahua erupted, sending volcanic ash over much of the western Ecuadorian lowland regions, which greatly reduced the expressions of the Chorrera and Cotocollao cultures.[2][3]
Eruptive phases
Past eruptive events have been broken down into four main eruptive units:
(Data below references) [4][5]
- Units I & II (~ 40-11 ka). Initial activity was marked by effusive dome building events. This included large voluminous Dacite lava domes, which is highly evolved magma. Eruptive volumes averaged 0.098 km³/ky during this phase. This is described as low to moderate eruptive rates. Ages of each eruption is poorly documented. Unit II had the highest eruptive volume. Half of total eruptive volume happened in this phase (~2.5 km³).
After initial volcanism, volcanic activity largely ceased for around 9 ka (~11-2.5 ka). The one exception was a minor event ~6 ka.
- Unit III (~2.5-2.3 ka). Volcanic activity resumed with a more violent and voluminous eruptive phases. These eruptions were highly explosive and created the 13 square kilometer caldera. Eruptive rates skyrocket to (~2.675 km³/ky), >6× higher than Unit II.
- Unit IV (~2.2 ka-present). This phase was characterized by central dome volcanic cone building. Eruptive rates are highest in this phase, (~12.578 km³/ky).
Current activity
Even though Pululahua has not erupted in almost 2,000 years, CO2 data shows an active magma chamber still exists under the volcano. Taking 350 soil samples from 3.36 square kilometers on the caldera floor, large amounts of CO2 is being degassed at around about 59–97 tonnes per day. This also poses a risk to animals and humans living in the caldera.[6]
References
- ↑ Petriello Jr, John (8 June 2007). "Thicknesses and Density-Current Velocities of a Low-Aspect Ratio Ignimbrite at the Pululagua Volcanic Complex, Ecuador, Derived from Ground Penetrating Radar" (in en). Tampa, FL: University of South Florida. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=5015&context=etd.
- ↑ Zeidler 471
- ↑ "Cotocollao (1800–350 a.C.)" (in es). https://www.culturaypatrimonio.gob.ec/cotocollao-1800-350-a-c/. Retrieved Jul 31, 2019.
- ↑ Vásconez Müller, Anais; Cashman, Katharine V.; Mitchell, Samuel J.; Vasconez, Francisco J. (3 August 2022). "The 2.6–2.3 ka explosive eruptive period of the Pululahua dome complex, Ecuador: insights from pyroclast analysis" (in en). Bulletin of Volcanology 84 (8). doi:10.1007/s00445-022-01590-4. PMC 9361993. https://www.researchgate.net/publication/362437598_The_26-23_ka_explosive_eruptive_period_of_the_Pululahua_dome_complex_Ecuador_insights_from_pyroclast_analysis. Retrieved 28 November 2025.
- ↑ Vasconez, F; Vásconez-Müller, A; Andrade, D (September 2019). "Magma output rates of Pululahua, the largest Ecuadorian dome complex" (in en). University of Bristol. https://www.researchgate.net/publication/336216327_Magma_output_rates_of_Pululahua_the_largest_Ecuadorian_dome_complex.
- ↑ Lamberti, M. C.; Sierra, D.; Cardellini, C.; Viveiros, F.; Vásconez Müller, A.; Vasconez, F. J.; Narváez, D. F.; Silva, C. et al. (1 September 2024). "Results of the CO2 diffuse degassing survey from the 2017 IAVCEI CCVG 13th volcanic gas workshop: Pululahua Dome Complex, Ecuador" (in en). Journal of Volcanology and Geothermal Research 453. doi:10.1016/j.jvolgeores.2024.108145. ISSN 0377-0273. https://www.sciencedirect.com/science/article/abs/pii/S0377027324001379. Retrieved 28 November 2025.
- Zeidler, J. A. "The Ecuadorian Formative." Helaine Silverman and William H. Isbell, eds. Handbook of South American Archaeology. New York: Springer, 2008. ISBN 978-0-387-75228-0.
- "Pululahua". Smithsonian Institution. https://volcano.si.edu/volcano.cfm?vn=352011.
[ ⚑ ] 0°02′17″N 78°27′47″W / 0.038°N 78.463°W
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