Enormous and far-reaching debris avalanche deposits from Sangay volcano (Ecuador): Multidisciplinary study and modeling the 30 ka sector collapse

Valverde, Viviana; Mothes, Patricia; Beate, Bernardo; Bernard, Julien

doi:10.1016/j.jvolgeores.2021.107172

Cited by 18 publications

(9 citation statements)

References 38 publications

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“…Using a reasonable proportionality principle, if we consider that the 19 May 2021 PDC, generated from the collapse of a mass < 10 4 m 3 , produced only a 1 mm thick ash deposit, we could argue that pinkish/reddish ash layers found within the stratigraphic sequences, with thickness up to several cm (such as the T2c of 64 , which is 5–6 cm thick), excluding the likely loss of a reworked portion, would have been generated by events some orders of magnitude greater, or by a series of repeated collapses close in time. Considering that many volcanoes worldwide are capable of producing PDCs, and in some cases tsunami waves (e.g., Pacaya, Guatemala 67 ; Sangay, Ecuador 68 ; Kambalani, Kamtchatka 69 2006; Fuji, Japan 70 ; Ritter Island, Papua New Guinea 71 ; Anak Krakatau, Indonesia 72 ) the prompt recognition of ash layers that correlate with this kind of phenomena would have a great impact on hazard assessment.…”

Section: Discussionmentioning

confidence: 99%

Physical and morphological characterization of the 19 May 2021 ash cloud deposit at Stromboli (Italy)

Pompilio

Carlo

et al. 2022

Sci Rep

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We report on the ash cloud related to the gravitational collapse of a portion of the Stromboli volcano crater rim that occurred on 19 May 2021. The collapse produced a pyroclastic density current (PDC) that spread along the northwest flank of the volcano and propagated in the sea for about 1 km. The PDC was associated with a convective ash cloud that rapidly dispersed eastward and deposited a thin layer (< 1 mm) of very fine pinkish ash over the village of Stromboli. The deposit was sampled shortly after the emplacement (within a few hours) and prior to any significant reworking or re-sedimentation. We present a comprehensive description of the deposit including dispersal, sedimentological characteristics and textural and geochemical features. We also compare the 19 May 2021 deposit with fine-ash deposits connected to other PDCs and landslides previously occurring at Stromboli and with the distal ash of a paroxysmal explosive eruption of Mt. Etna volcano. Results indicate that the distributions of the mass on the ground and of the grain size are not correlated with the distance from the source. Also, the componentry reflects a preponderance of remobilized material ingested by the PDC. Therefore, the great amount of fine ash can be ascribed to clasts comminution processes, although the prevalence of dense crystalline components records an overall equiaxial shape, revealing a paucity of elongated clast with complex morphology. Furthermore, the outcomes of this work aim to create a collection of data of a co-PDC ash cloud that may prove useful for comparison with other deposits worldwide.

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Section: Discussionmentioning

confidence: 99%

Physical and morphological characterization of the 19 May 2021 ash cloud deposit at Stromboli (Italy)

Pompilio

Carlo

et al. 2022

Sci Rep

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“…The Pacaya VDAD (Figure 10A) is also characterized by mixed facies containing homogeneous basaltic jigsaw-fit blocks, disturbed pyroclastic sequences and pumices incorporated by the ingestion of pre-collapse ignimbrites in a sandy-grain size matrix and hummocks with heights between 5 and 15 m (Kitamura and Matías, 1995;Vallance et al, 1995). Another two massive basalticandesite VDADs are recognized at Sangay volcano; older-S1, 250-100 ka, and younger-S2, about 30 ka, and they involve 29 and 32.5 km 3 of material, from which S2 is among the most significant volcanic avalanches in the world associated with continental arc volcanoes (Valverde et al, 2021). In S2 at least 541 hummocks have been identified and they have heights of 2-40 m, with largest sizes observed at 40-50 km from the vent (ibid).…”

Section: Characteristics Of Debris Avalanche Depositsmentioning

confidence: 99%

“…Some of these sector collapses involved a volume of tens of km 3 , and produced notable collapse scars of few km wide. The related VDADs are similar in terms of internal architecture, size and mobility to those sourced from intermediate or silicic volcanoes; however, a few continental examples are outstanding in terms of their extension and volume: (1) one of the longest run-outs reported in the literature achieved by the Planchón Teno VDAD (Chile, 95 km;McPhail, 1973;Naranjo et al, 1999) which is an example of a confined debris avalanche (Tost et al, 2015) in Andean Valleys; and (2) two mafic VDADs from Sangay volcano (Ecuador) which are among the most significant in the world, and they reached up to 60 km from the source despite they are unconfined (Valverde et al, 2021). Therefore, it is necessary to assess sector collapse hazard from rapidly growing mafic volcanoes, using field mapping of ancient VDAD deposits, implementing detailed geotechnical evaluations (Voight, 2000;Apuani et al, 2005;del Potro and Hürlimann, 2009;Schaefer et al, 2013Schaefer et al, , 2015 and carrying out instability monitoring and landslide prediction, as it has been developed for some active mafic volcanoes in the world (Solaro et al, 2010;Intrieri et al, 2013;Nolesini et al, 2013;Poland et al, 2017;Schaefer et al, 2019).…”

Section: Concluding Remarks and Future Researchmentioning

confidence: 99%

Volcanic Lateral Collapse Processes in Mafic Arc Edifices: A Review of Their Driving Processes, Types and Consequences

et al. 2021

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Volcanic cones are frequently near their gravitational stability limit, which can lead to lateral collapse of the edifice, causing extensive environmental impact, property damage, and loss of life. Here, we examine lateral collapses in mafic arc volcanoes, which are relatively structurally simple edifices dominated by a narrow compositional range from basalts to basaltic andesites. This still encompasses a broad range of volcano dimensions, but the magma types erupted in these systems represent the most abundant type of volcanism on Earth and rocky planets. Their often high magma output rates can result in rapid construction of gravitationally unstable edifices susceptible both to small landslides but also to much larger-scale catastrophic lateral collapses. Although recent studies of basaltic shield volcanoes provide insights on the largest subaerial lateral collapses on Earth, the occurrence of lateral collapses in mafic arc volcanoes lacks a systematic description, and the features that make such structures susceptible to failure has not been treated in depth. In this review, we address whether distinct characteristics lead to the failure of mafic arc volcanoes, or whether their propensity to collapse is no different to failures in volcanoes dominated by intermediate (i.e., andesitic-dacitic) or silicic (i.e., rhyolitic) compositions? We provide a general overview on the stability of mafic arc edifices, their potential for lateral collapse, and the overall impact of large-scale sector collapse processes on the development of mafic magmatic systems, eruptive style and the surrounding landscape. Both historical accounts and geological evidence provide convincing proofs of recurrent (and even repetitive) large-scale (>0.5 km3) lateral failure of mafic arc volcanoes. The main factors contributing to edifice instability in these volcanoes are: (1) frequent sheet-like intrusions accompanied by intense deformation and seismicity; (2) shallow hydrothermal systems weakening basaltic rocks and reducing their overall strength; (3) large edifices with slopes near the critical angle; (4) distribution along fault systems, especially in transtensional settings, and; (5) susceptibility to other external forces such as climate change. These factors are not exclusive of mafic volcanoes, but probably enhanced by the rapid building of such edifices.

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“…The most recent notable activity began with the eruptions of Tungurahua and Guagua Pichincha in September and October 1999, respectively, and since then three additional volcanoes (El Reventador, Cotopaxi, Sangay) have erupted in continental Ecuador [Hall and Mothes 2008;Robin et al 2008;Hidalgo et al 2018;Almeida et al 2019;Ortiz et al 2020;Valverde et al 2021]. These volcanoes showed different eruptive styles and eruption durations and led to different impacts on the population: Guagua Pichin-cha's eruption mainly resulted in ashfall on the capital city of Quito and the consequences (especially on the younger population) lasted for a few months [Naumova et al 2007]; Tungurahua's eruption lasted 16 years with explosions that occasionally caused significant ash emissions and pyroclastic density currents (PDC) that impacted local communities in various forms [Few et al 2017]; El Reventador and Sangay volcanoes continue to erupt almost without interruption to this day, with outbursts of explosions and small to medium PDCs and a relatively rapid landscape change [Ortiz et al 2021;Valverde et al 2021]; Cotopaxi volcano's brief reactivation in 2015 lasted for a few months with a paroxysm with a volcano explosivity index (VEI) of 2 and a lowlevel ash plume that caused social distress in nearby (∼14 km) communities [Hidalgo et al 2018;Gomez-Zapata et al 2021]. The high spatial density of active Holocene volcanoes and associated volcanic hazards has impacted pre-Columbian populations [Isaacson and Zeidler 1999;Hall and Mothes 2008;Vallego Vargas 2011;Le Pennec 2013] and continues to impact contemporary populations [Le Pennec et al 2008;Biass et al 2012;Le Pennec et al 2012] in the region.…”

Section: Geological Context Of Ecuadormentioning

confidence: 99%

Reviewing volcano hazard and risk communications in Ecuador: experiences from a fast-format workshop

et al. 2021

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Hazard and risk communication requires the design and dissemination of clear messages that enhance people’s actions before, during, and after volcanic crises. To create effective messages, the communication components such as message format and content, must be considered. Changes in technology are changing the way people communicate at an ever-increasing pace; thus, we propose revising the basic components of the communication process to improve the dialogue between scientists and the public. We describe communication issues during and outside volcanic crises in Ecuador and assess possible causes and consequences. These ideas were discussed during the short-duration “Volcano Geophysical Principles and Hazards Communications” Workshop in Baños, Ecuador in 2019. We review and propose communication strategies for volcanic hazards and risks that resulted from the workshop discussions and experiences of experts from the Instituto Geofísico (IG-EPN), local and international professors involved in volcano research and communication, and students from universities across Ecuador.

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Enormous and far-reaching debris avalanche deposits from Sangay volcano (Ecuador): Multidisciplinary study and modeling the 30 ka sector collapse

Cited by 18 publications

References 38 publications

Physical and morphological characterization of the 19 May 2021 ash cloud deposit at Stromboli (Italy)

Physical and morphological characterization of the 19 May 2021 ash cloud deposit at Stromboli (Italy)

Volcanic Lateral Collapse Processes in Mafic Arc Edifices: A Review of Their Driving Processes, Types and Consequences

Reviewing volcano hazard and risk communications in Ecuador: experiences from a fast-format workshop

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