Silvana Hidalgo

Escuela Politécnica Nacional | EPN · Instituto Geofísico

The unusually high number of volcanoes in the Ecuadorian Arc, located in the deformation zone of the continental North Andean Sliver, coincides with the projection of the major oceanic structures observed in the Nazca Plate, such as the Carnegie Ridge and the Grijalva fracture zone. Although the relationship between this tectonic setting and volcan...

Identifying the sources of distal tephra in marine sediments or polar ice provides clues on the dynamic and large-scale impact of major volcanic eruptions. However, determination of the volcanic source of distal tephra is challenging due to size-dependent fractionation during atmospheric transport that modifies the mineral, chemical and even isotop...

Pese a los múltiples esfuerzos por comprender la evolución temporal del Arco Volcánico Ecuatoriano, la historia evolutiva de los edificios volcánicos más antiguos permaneció poco estudiada. La Universidad Paris-Saclay, el Instituto Geofísico de la Escuela Politécnica Nacional y el Instituto de Investigación para el Desarrollo de Francia llevaron a...

Arc volcanism arises from the release of fluids from the descending slab, which enables melting in the mantle wedge by lowering the solidus temperature. Metasomatism—compositional alteration by fluids—of the mantle is known to have an important role in magma production in volcanic arcs over long spatial and temporal scales. However, the episodic er...

On 2 December, 2021 we recorded a sequence of drumbeat seismic events at Sangay volcano. This sequence lasted several hours and resulted in two explosive emissions whose eruptive columns reached 9 km above crater. Unexpectedly, these explosions did not produce any ash fallout in the inhabited areas around the volcano. This drumbeat sequence was pro...

Tephra layers preserved in marine sediments are strong tools to study the frequency, magnitude and source of past major explosive eruptions. Thirty‐seven volcanoes from the Ecuadorian and Colombian arc, in the northern Andes, experienced at least one eruption during the Holocene. The volcanic hazard is therefore particularly high for the populated...

Volcanic ash is a hazard to human health and activities. Accurate and timely forecasts coupled with effective communication about the dispersion and fallout of volcanic ash during explosive events are essential to reduce impacts on local communities and limit economic losses. In this study, we present the first detailed description of an eruptive p...

Since the VEI 4 eruption of November 2002, El Reventador volcano (Ecuador) has been the site of persistent open-vent activity characterized by frequent (hourly) Vulcanian—strombolian explosions and occasional (every few years) effusion of lava flows. The conduit processes that sustain this continuous eruptive activity are still poorly understood. H...

The monitoring of the frequency, intensity/magnitude and dynamics of explosive events at volcanoes in a state of unrest is key to surveying and forecasting their activity. Thermal and visual video observations of eruptive phenomena, and their correlation with data from deformation and seismic networks, are often limited by technical constraints inc...

In Ecuador, a country with several active volcanoes and with four eruptions in the last decade in the continental arc, it is very likely that high-voltage transmission lines cross volcanic hazard zones on their routes. Here, we quantify the impact of fresh volcanic ash from the hydromagmatic Cotopaxi-2015 and the magmatic Tungurahua-2016 eruptions...

The volcanoes of Galápagos, Ecuador, are among the most active in the world, with an average of five eruptions per decade. Monitoring and communication of their activity are essential for timely management of events. In this context, the Instituto Geofísico de la Escuela Politécnica Nacional carries out constant surveillance of Galápagos volcanoes...

Pyroclastic currents (PCs) and tephra fallout are among the major volcanic hazards at explosive volcanoes and have been widely studied over the past decades in order to model the physical processes controlling them. The aim of such efforts is using numerical models for producing probabilistic hazard maps, and complementing such maps with a quantifi...

We analyzed changes in the long-term vegetation cover and in fire activity over the past 5,000 years in the Ecuadorian páramo using a sediment core from Papallacta (Ecuador). The chronology is constrained by three tephra layers and 32 AMS 14C ages, and 168 samples yielded a high-resolution record of environmental changes. We estimated the upslope w...

Sangay is one of the most active volcanoes in Ecuador, as it has been almost continuously erupting at least since the seventeenth century. However, because of its remote location and low associated risk to human population, little is known about its eruptions. Here we summarize Sangay’s volcanic activity from January 2001 to May 2020, based on grou...

The International Symposium on Andean Geodynamics (ISAG) is an international conference that was held, on average, every 3–4 years in different European cities between 1990 (Grenoble) and 2008 (Nice). These symposia usually offer an opportunity for researchers from Latin American countries and Europe as well as other countries to review the state o...

Plain Language Summary Magmatic gas released by intraplate, hot‐spot related volcanism can offer insight into the abundance and distribution of volatiles in the Earth's upper mantle. Unfortunately however, the available data set for hot spot magmatic gases is sparse and incomplete, due to relatively infrequent eruptions and the remote location of m...

Tephra fallout hazard assessment is undertaken with probabilistic maps that rely on numerical models. Regarding maps production, the input parameters of the model (including atmospheric conditions), the physical approximations of the numerical simulations, and the probabilities of occurrence of different eruption types in specific time frames are a...

The youngest volcanism of the Ecuadorian Volcanic Front (Western Cordillera) is mainly dominated by highly explosive events, including the growth and violent destruction of lava domes, and the formation of thick pyroclastic sequences. Deposits associated with such eruptive dynamics have been identified at Iliniza, a compound volcano located in the...

Noventa y ocho volcanes cuaternarios han sido identificados en los Andes ecuatorianos y Galápagos de los cualesnueve han experimentado erupciones al menos una vez en los últimos veinte años. Adicionalmente, alrededor del35 % de la población ecuatoriana vive en zonas que podrían ser afectadas durante futuras erupciones. El InstitutoGeofísico de la E...

Ninety-eight Quaternary volcanoes have been identified in the Ecuadorian Andes and the Galápagos Islands, from them, nine experienced at least one eruption in the last twenty years. Additionally, about 35 % of the Ecuadorian population live in areas that could be affected by future volcanic eruptions. The Instituto Geofísico of the Escuela Politécn...

The Billecocha plateau (4000 m a.s.l.) lies in the high elevation Ecuadorian Andes volcanic arc. It overhangs by 2000 m above the interandean valley. Both the plateau and surrounding volcanoes are heavily affected by active faulting characterized by straight, sharp and discontinuous scarps within a 6 km wide and 24 km long corridor. Contrasting int...

Future occurrence of explosive eruptive activity at Cotopaxi and Guagua Pichincha volcanoes, Ecuador, is assessed probabilistically, utilizing expert elicitation. Eight eruption types were considered for each volcano. Type event probabilities were evaluated for the next eruption at each volcano and for at least one of each type within the next 100...

During the last two decades, Sangay has been one of the most active Ecuadorian volcanoes. However, because of its remote location and logistically difficult access, monitoring Sangay is a challenging task. The IG-EPN tackled this problem by expanding its terrestrial monitoring network and complementing it with the available satellite data. On 7th M...

The Northern Andes of Ecuador contain some of the most active volcanic systems in the Andes and extend over a broad region from the Western Cordillera to the Subandean Zone. While it is known that the arc straddles a range of basement compositions, from accreted mafic oceanic terranes in the west to silicic continental terranes in the east, the det...

The use of numerical models aimed at producing probabilistic maps is becoming more and more a common practice for tephra fallout hazard assessment. However, it is important to complement such maps with a quantification of the major sources of aleatoric/epistemic uncertainties, to help stakeholders and decisionmakers in taking informed decisions. In...

Based on manually analyzed waveforms recorded by the permanent Ecuadorian network and our large aftershock deployment installed after the Pedernales earthquake, we derive three‐dimensional Vp and Vp/Vs structures and earthquake locations for central coastal Ecuador using local earthquake tomography. Images highlight the features in the subducting a...

Volcanic plumes are common and far-reaching manifestations of volcanic activity during and between eruptions. Observations of the rate of emission and composition of volcanic plumes are essential to recognize and, in some cases, predict the state of volcanic activity. Measurements of the size and location of the plumes are important to assess the i...

Trace volatile elements like He are key for understanding the mantle source signature of magmas and to better constrain the relative roles of subduction and crustal processes to the variability of along-arc chemical and isotopic signatures of magmatic fluids. Here we report on noble gas abundances and isotopic data of Fluid Inclusions (FIs) in erup...

Cuicocha Caldera is the youngest eruptive center of Cotacachi-Cuicocha Volcanic Complex, located at the north of Ecuador. The caldera contains a lake of 3.95 km2 surface, and a maximum depth of 148 m. Cuicocha Lake is characterized by the presence of CO2 gaseous diffuse emissions, perceptible as bubbling zones. Since 2011, CO2 diffuse flux measurem...

Volcanic plumes are common and far-reaching manifestations of volcanic activity during and between eruptions. Observations of the rate of emission and composition of volcanic plumes are essential to recognize, and in some cases predict, the state of volcanic activity. Measurements of the size and location of the plumes are important to assess the i...

New K-Ar ages obtained on juvenile pumice glass shards indicate that the Chalupas ignimbrite, one of the main Pleistocene tephra markers of the Ecuadorian arc, was emplaced at 216 ± 5 ka. Morphology and major and trace element contents of the glass shards are similar to those of ash layers from deep-sea cores and allow correlation between continent...

Numerical modeling of tephra dispersal and deposition is essential for evaluation of volcanic hazards. Many models consider reasonable physical approximations in order to reduce computational times, but this may introduce a certain degree of uncertainty in the simulation outputs. The important step of uncertainty quantification is dealt in this pap...

In the northern Andes, the Ecuadorian arc presents a large number of Quaternary volcanoes, spread over a rather restricted area. The origin of this volcanic clustering is not well understood, and only a few chronological data older than the Holocene are available in northern Ecuador to document the arc development stages. In this study, we present...

Previous studies demonstrated the existence of a marked temporal geochemical variation of several long-lived volcanoes of the Ecuadorian arc (e.g. Cayambe, Mojanda-Fuya Fuya, Pichincha, Atacazo-Ninahuilca), that includes an evolution from typical calk-alcaline arc magmas present at the older edifices to adakite-like compositions in the younger edif...

Hazard maps constitute a guiding tool for land use planning and emergency response. Quito, the capital of Ecuador, is surrounded by several active and potential active volcanoes, such as AtacazoNinahuilca Volcanic Complex (ANVC). The geological record indicates that Plinian eruptions at ANVC have an average Frequency of one event every 2513±193 yea...

Recent long-term observations of the bromine monoxide (BrO) to sulphur dioxide (SO2) molar ratio in volcanic plumes have suggested a link between changes in the BrO/SO2 ratio and the volcanic activity. Nevertheless, understanding of the mechanisms determining this link is still limited due to the lack of studies on volcanic bromine release from the...

Continental arc lavas display geochemical signatures that reflect both mantle metasomatism by slab fluids or melts and extensive differentiation of magmas within crustal reservoirs. The relative effect of source and crustal processes are difficult to disentangle based on whole-rock compositions. This issue is critical in Ecuador where volcanism occ...

Eruption style and dynamics are controlled by various parameters including magma supply rate, magma viscosity, volatile content, and the permeability of the conduit. Rapid changes of these parameters can significantly modify the hazards associated to the eruption processes and understanding their relationship with multiparametric geophysical monito...

The 1982 and 2015 eruptions were the first at Wolf volcano, Galápagos Archipelago, with eyewitness accounts and satellite imagery. Both eruptions were characterized by a rapid and intense initial phase, with multiple eruptive vents, leading to the formation of large ‘a‘ā lava fields and scarce pāhoehoe mostly associated with the waning phases. The...

This study focuses on the construction and evolution through time of volcanic edifices located in the southern part of the Ecuadorian arc, with the objective to contribute to a better understanding of the interactions between magmatism, slab geometry and the activity of tectonic faults. Our new groundmass K-Ar ages obtained for a dozen volcanoes fr...

The 1982 and 2015 eruptions are the first at Wolf volcano, Galápagos Archipelago, with eyewitness accounts and satellite imagery. Both eruptions are characterized by a rapid, intense initial phase and multiple eruptive vents leading to the formation of large ‘a‘ā lava fields with scarce pāhoehoe deposits, mostly associated with the waning phases. T...

After eight years of quiescence, Fernandina volcano experienced two short-lived eruptions, on 4 September 2017 and 16 June 2018. The eruptions were characterized by very short periods of unrest that started a few hours before the initiation of the eruptive activity. On the other hand, Sierra Negra volcano (Isabela Island) began a new eruptive perio...

Constraining arc magma sources at continental arc settings is a delicate task, because chemical signatures from crustal processes obscure the slab and mantle signatures. Here, we present major, trace, and volatile element compositions of olivine-hosted melt inclusions (Fo82–89) selected from the most primitive lavas (Mg# > 60) from two Ecuadorian v...

Ecuador’s last severe volcanic disaster occurred 141 years ago when lahars from Cotopaxi destroyed several villages and part of Latacunga causing thousands of victims. 24 volcanoes in Continental Ecuador and 13 volcanoes in Galápagos are considered as potentially active. Since 1983, the IG-EPN works to create a monitoring network able to detect vol...

After eight years of quiescence, Fernandina volcano experienced two short-lived eruptions, on 4 September 2017 and 16 June 2018. The eruptions were characterized by very short periods of unrest that started a few hours before the initiation of the eruptive activity. On the other hand, Sierra Negra volcano (Isabela Island) began a new eruptive perio...

Through integration of multiple data streams to monitor volcanic unrest scientists are able to make more robust eruption forecast and to obtain a more holistic interpretation of volcanic systems. We examined gas emission and gas geochemistry and seismic and petrologic data recorded during the 2015 unrest of Cotopaxi (Ecuador) in order to decipher t...

Recent geophysical evidence for large-scale regional crustal inflation and localized crustal magma intrusion has made Lastarria volcano (northern Chile) the target of numerous geological, geophysical, and geochemical studies. The chemical composition of volcanic gases sampled during discrete campaigns from Lastarria volcano indicated a well-develop...

Satellite remote sensing is a valuable method for detecting and quantifying sulfur dioxide (SO2) emissions at volcanoes. The use of ultra‐violet satellite instruments for monitoring purposes has been assessed in numerous studies, but there are advantages to using infrared measurements, including that they can operate at night and during high latitu...

This study investigated a new direction for improving the decision making of populations at risk in the context of uncertain environmental events, such as volcanic hazards. According to the risk as feelings theory and dual process models, situations with certain outcomes do not necessarily require the use of affect heuristics (e.g., experienced fee...

We evaluated NOVAC (Network for Observation of Volcanic and Atmospheric Change) gas emission data from the 2015 eruption of the Cotopaxi volcano (Ecuador) for BrO∕SO2 molar ratios. The BrO∕SO2 molar ratios were very small prior to the phreatomagmatic explosions in August 2015, significantly higher after the explosions, and continuously increasing u...

Volcanic eruptions of intermediary and silica-rich magmas (andesites, dacites and rhyolites) in convergent arc settings generate voluminous and explosive eruptions that can strongly affect human activity and have significant environmental impacts. It is therefore crucial to understand how these magmas are generated in order to anticipate their pote...

We evaluated NOVAC (Network for Observation of Volcanic and Atmospheric Change) gas emission data from the 2015 eruption of Cotopaxi volcano (Ecuador) for BrO/SO2 molar ratios. Statistical analysis of the data revealed a conspicuous periodic pattern with a periodicity of about two weeks in a three month time series. While the time series is too sho...

Submission 1256 The Cotopaxi 2015 eruptive phase: insights from gas and glass Cotopaxi volcano (5,897 m) is located 50 km south of Quito, the capital of Ecuador. In April 2015, a progressive increase in the amplitude of transient seismic events initiated volcanic unrest. Starting on May 20, an increase in SO2 emissions from ~500 t/d to ~3000 t/day...

Submission 617 Subduction dynamics, mantle and crustal processes at arc volcanoes, investigated by relative CO2/ST abundances and 3He/4He isotope signatures. The investigation of the relative abundance of volatiles allows for a better constrain of the origin and recycling efficiency of these elements via subduction. Here, we attempt to correlate al...