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Journal Articles Journal of South American Earth Sciences Year : 2021

Pululahua dome complex, Ecuador: eruptive history, total magma output and potential hazards

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S. Daniel Andrade
  • Function : Author
Anais Vásconez Müller
  • Function : Author
Francisco J. Vasconez
  • Function : Author
Bernardo Beate
  • Function : Author
Jorge Aguilar
  • Function : Author

Abstract

Pululahua is a potentially active dome complex located 15 km north of Quito. It is composed of sixteen dacitic-andesitic lava domes located inside and around a semi-rectangular depression. We divide its eruptive history into: (1) a first member characterized by effusive lava dome growth and collapse (Units I and II, >18-12 ka), (2) a second member consisting of at least four explosive eruptive phases (VEI ~4), responsible for the formation of a caldera-like depression (Unit III, 2.6-2.3 ka cal BP), and (3) a final member encompassing partially explosive dome growth inside the depression (Unit IV, 2.2 ka cal BP). Rock samples show no significant geochemical changes over time, except for a slight decrease in SiO2 and a minor increase in MgO and Fe2O3 towards younger magmas. In addition, based on field measurements, a total minimum bulk volume of all domes and pyroclastic deposits is estimated at ~5.75 ± 0.14 km³, yielding a dense rock equivalent of ~4.24 ± 0.1 km³ and a total erupted magma mass of 10.58 ± 0.16 E+12 kg. Finally, we put forward three future hazard scenarios that could affect the population in the proximal area (>70 k people): (1) an unrest period involving increased seismic events, volcanic gas emissions and potentially small phreatic explosions, (2) the effusive and/or slightly explosive growth and destruction of lava domes accompanied by block-and-ash flows and tephra fall, and (3) large explosive events (VEI ~4) that generate regional tephra fall and massive pyroclastic density currents.
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Dates and versions

insu-03745271 , version 1 (04-08-2022)

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S. Daniel Andrade, Anais Vásconez Müller, Francisco J. Vasconez, Bernardo Beate, Jorge Aguilar, et al.. Pululahua dome complex, Ecuador: eruptive history, total magma output and potential hazards. Journal of South American Earth Sciences, 2021, 106, ⟨10.1016/j.jsames.2020.103046⟩. ⟨insu-03745271⟩
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