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Solid Earth An interactive open-access journal of the European Geosciences Union

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doi:10.5194/se-2016-159
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
14 Dec 2016
Review status
A revision of this discussion paper was accepted for the journal Solid Earth (SE) and is expected to appear here in due course.
Dynamics and style transition of a moderate, Vulcanian-driven eruption at Tungurahua (Ecuador) on February 2014: pyroclastic deposits and hazard considerations
Jorge Eduardo Romero1, Guilhem Amin Douillet2, Silvia Vallejo Vargas3, Jorge Bustillos4, Liliana Troncoso4, Juan Díaz Alvarado1, and Patricio Ramón3 1Departamento de Geología, Universidad de Atacama, Copiapó, Chile
2Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Munich, Germany
3Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador
4Escuela de Geología, Facultad de Geología, Minas, Petróleos y Ambiental (FIGEMPA), Universidad Central del Ecuador Quito, Ecuador
Abstract. The ongoing eruptive cycle of Tungurahua volcano (Ecuador) since 1999 has been characterized by over 15 paroxysmal phases interrupted by periods of relative calm. Those phases included Strombolians, Vulcanians and one Subplinian eruptions and they generated tephra fallouts, pyroclastic density currents (PDCs) and lava flows. The 01 February 2014 eruption occurred after 75 days of quiescence. Two days before the eruption, a gradual increase of seismicity associated with sporadic weak ash emissions occured. Between 13:30 and 16:30 UTC of the 01 February, a swarm of volcano tectonic and long period earthquakes was detected and announced the possibility of an eruption within hours or days. After a few hours without surface manifestations, two short-lived Vulcanian explosions triggered the paroxysmal phase at 22:39 UTC which lasted 40 min and produced an eruptive column 13.4 km in height sustained during about 9 min. The activity evolved at 23:36 UTC into sporadic Strombolian explosions with discrete ash emissions and continued for several weeks.

Both tephra fall and PDCs were studied for their dispersal, sedimentology, volume and eruption source parameters. Tephra was distributed around 240° to the S-SW of the volcano, and the bulk deposit volume is estimated to be 1.53 ± 0.35 × 10−2 km3 (4.76 ± 2.23 × 106 m3 DRE; VEI 3). PDCs descended by 9 ravines of the N-NW flanks. It was one of Tungurahua’s largest eruptions, after the August 2006 Subplinian event. The Vulcanian eruptive mechanism is interpreted to be related to a steady magma ascent and the rise in over-pressure in a blocked conduit (plug) and/or a depressurized solidification front. The transition to Strombolian style is well documented from the tephra fall componentry. In any of the interpretative scenari, the short-lived precursors for such a major event as well as the unusual tephra dispersion pattern urge for renewed hazard considerations at Tungurahua.


Citation: Romero, J. E., Douillet, G. A., Vallejo Vargas, S., Bustillos, J., Troncoso, L., Díaz Alvarado, J., and Ramón, P.: Dynamics and style transition of a moderate, Vulcanian-driven eruption at Tungurahua (Ecuador) on February 2014: pyroclastic deposits and hazard considerations, Solid Earth Discuss., doi:10.5194/se-2016-159, in review, 2016.
Jorge Eduardo Romero et al.
Jorge Eduardo Romero et al.
Jorge Eduardo Romero et al.

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Short summary
The 01 February 2014 eruption of Tungurahua volcano (Ecuador) was the second largest one since the re-awakening in 1999. The eruption showed precursory signs only 48 hours before the eruption. The main explosions produced a 13 km eruptive column and pyroclastic density currents that reached the base of the volcano. Here we document the deposits related to the eruption, and infer eruption mechanisms and transport processes.
The 01 February 2014 eruption of Tungurahua volcano (Ecuador) was the second largest one since...
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