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Timely acquisition of ash cloud heights is crucial for aviation safety and forecasting volcanic ash dispersion and fallout. Since visual observations are not always available, we assess the suitability of retrieving ash cloud heights from brightness temperature and plume direction observed in GOES-16 satellite imagery, VOLCAT solutions, and Washington-VAAC advisories during the 2022–2023 eruption of Cotopaxi volcano, Ecuador. We find that these satellite-derived height estimates consistently yield lower values than visual cameras. While the plume direction method and Washington-VAAC advisories produce the closest approximations, they also exhibit significant deviations. Remarkably, the brightness temperature method, despite producing the lowest height values, shows the best linear regression with visual observations. Near-real-time retrieval of ash cloud height from GOES-16 imagery is a promising alternative to direct visual observation, particularly at night, in adverse weather, or for remote volcanoes, especially if improvements, such as incorporating high-resolution local meteorological models, are introduced.

Volcanic debris flows (lahars) are highly destructive volcanic phenomena and present significant challenges in numerical simulation. This manuscript tackles the three fundamental requirements for modelling gravitational flows: determining plausible source configurations; selecting suitable topographic data; and employing appropriate mathematical models to assess the current hazard posed by long-distance lahars at Cotopaxi volcano. After incorporating these elements, we successfully simulated the characteristics of a future 1877-type lahar under current conditions, accounting for glacier size and topography. For the source conditions, or “scenario”, we identified 27 equidistant source locations along the lower edge of the current glacier’s extent. Each source was assigned a hydrograph based on the weighted volume of water available on Cotopaxi’s current glacier. Additionally, we introduced a methodology for quantifying channel width when high-resolution digital elevation models (DEMs) are available. This method enabled us to determine the minimum pixel size required for accurate representation of ravine shapes. While higher resolution DEMs demand robust computational resources and extended computational timeframes, we upscaled Cotopaxi’s DEM from 3 m to 15 m to balance accuracy and efficiency, as a 15-m DEM capture over 90% of the topography and reduces computing time significantly. Optimizing DEM selection is crucial, especially when contemplating future ensemble approaches. After employing the dynamic-based model Kestrel, parameterised for large lahars, we obtained predictions closely aligned with field observations, historical flow conditions inferred for the 1877 lahar-event, and results from previous simulation studies. Notably, we observed higher depths and speeds in canyons compared to plains, consistent with historical reports and previous studies. Minor discrepancies in the inundation area, when compared with existing hazard maps, emphasize the importance of understanding flow dynamics and lahar trajectories for effective hazard assessment and mitigation strategies. Furthermore, our results contribute valuable information to current hazard maps and can aid in damage quantification and cost/benefit analyses, particularly when planning the construction of mitigation infrastructure.

Abstract 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 on the dielectric characteristics of ANSI 52–3 suspension insulators made of porcelain and glass, under moist conditions. The experiments include two methodologies to measure the performance of the insulators in real-time: the minimum insulator flashover voltage (FOVmin) and the dielectric loss factor angle. Both allow quantifying i) the critical voltage that the insulators can withstand prior to flashover occurrence and, ii) the strong fluctuating behavior that the insulators undergo in an ashy environment. Based on six contamination scenarios, we found that there is a higher chance of flashover if the insulators are completely blanketed (top and bottom) even with a fine ash layer (1 mm), than if they are covered just at the top. Our results further show that the ash of Cotopaxi-2015 eruption has a higher chance of leading to insulator failure because of its higher conductivity (i.e. higher leachate content) than that of Tungurahua-2016. Additionally, we identify two critical voltages prior to electrical flashover on the insulators of 28.25 kV and 17.01 kV for the 230 kV and 138 kV Ecuadorian transmission lines, respectively. Finally, we present a simple impact evaluation for the main Ecuadorian transmission lines based on the outcomes of this research and the official volcanic hazard maps for Cotopaxi and Tungurahua volcanoes.

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 using geophysical monitoring, remote sensing, and field campaigns with the support of the Dirección del Parque Nacional Galápagos. Collaborations with national emergency agencies and international scientists have been key to ensuring the protection of the population, economic activities, and endemic fauna of Galápagos. Since 2010, there have been numerous changes in the way volcanic unrest and eruptions are detected and communicated to decision-makers and the general public. This paper summarizes six eruptions and one period of unrest from different Galápagos volcanoes that occurred in the last decade to illustrate and discuss the evolution of surveillance and hazard communication.

Volcanic debris flows (lahars) are highly destructive volcanic phenomena and present significant challenges in numerical simulation. This manuscript tackles the three fundamental requirements for modelling gravitational flows: determining plausible source configurations; selecting suitable topographic data; and employing appropriate mathematical models to assess the current hazard posed by long-distance lahars at Cotopaxi volcano. After incorporating these elements, we successfully simulated the characteristics of a future 1877- type lahar under current conditions, accounting for glacier size and topography. For the source conditions, or "scenario", we identified 27 equidistant source locations along the lower edge of the current glacier's extent. Each source was assigned a hydrograph based on the weighted volume of water available on Cotopaxi's current glacier. Additionally, we introduced a methodology for quantifying channel width when high-resolution digital elevation models (DEMs) are available. This method enabled us to determine the minimum pixel size required for accurate representation of ravine shapes. While higher resolution DEMs demand robust computational resources and extended computational timeframes, we upscaled Cotopaxi's DEM from 3 m to 15 m to balance accuracy and efficiency, as a 15-m DEM capture over 90% of the topography and reduces computing time significantly. Optimizing DEM selection is crucial, especially when contemplating future ensemble approaches. After employing the dynamic-based model Kestrel, parameterised for large lahars, we obtained predictions closely aligned with field observations, historical flow conditions inferred for the 1877 lahar-event, and results from previous simulation studies. Notably, we observed higher depths and speeds in canyons compared to plains, consistent with historical reports and previous studies. Minor discrepancies in the inundation area, when compared with existing hazard maps, emphasize the importance of understanding flow dynamics and lahar trajectories for effective hazard assessment and mitigation strategies. Furthermore, our results contribute valuable information to current hazard maps and can aid in damage quantification and cost/benefit analyses, particularly when planning the construction of mitigation infrastructure. [ABSTRACT FROM AUTHOR]

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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 ground-based data, satellite-derived observations and chemical analysis of its erupted products. During the analyzed period, Sangay's activity changed from continuous to episodic, as revealed by seismic, thermal and ash emission data. We identified three main eruptive periods: the first, from 2001 to 2013, extruded a cumulative volume of 100 ± 50 million m3 of lava through long-lived activity; the second emitted 54 ± 27 million m3 in four short-lived episodes, which occurred once every year from 2015 to 2018; and finally, a third period since 2019, which has continuous but fluctuating intensity, and shows a significant increase in the extruded lava volume (172 ± 86 million m3 until May 31, 2020). Our results show a marked change in the eruption frequency and a significant increase in average discharge rate over time, although surface activity remained similar, with lava flows, small explosions and ash venting. We propose that three magmatic processes acted to explain the observed changes: between 2001 and 2013 the long-living low-intensity eruptions were promoted by buoyancy, while since 2019 similar but more intense activity was triggered by mass injections. In contrast, the episodic activity in between probably resulted from volatile exsolution due to crystallization (second boiling). Transitions between these three regimes are presumably the result of varying mass inflow rates. Our results provide insights into eruptive style transitions commonly observed at volcanoes of intermediate composition, such as Sangay, over a timescale of several years. [ABSTRACT FROM AUTHOR]