Deception Island is one of the most active volcanoes in Antarctica, with more than 20 monogenetic eruptions during the Holocene. The latest episodes of 1967, 1969, and 1970 have shown that volcanic ...activity on Deception Island can become a concern for tourists, scientists, and military personnel working on or near the island.
The objective of this work is to identify eruptive processes and the geomorphic evolution of post-caldera monogenetic volcanic edifices at Deception Island by morphometric analyses, supported by field observations. Morphometric analysis has been used since the 1970s to analyse scoria cones, but it has rarely been applied to other monogenetic volcanoes, such as tuff cones and tuff rings. Tuff cones and tuff rings represent the most common landforms during Deception Island's recent geological past, with over 70 scattered eruptive vents inside and along the caldera rim. These volcanic landforms have been studied based on field observations and later, Digital Elevation Model analyses. Their geometry ranges from 10 to 100 m in height, and diameters vary between 300 and 2500 m. The morphometric data suggest that tuff cones have a more circular crater than tuff rings, with a significant separation between the two landforms using the height (Hco) and basal width (Wco) parameters. Tuff cones have Hco/Wco ratios with values between 0.04 and 0.16 and outer slopes between 7° and 34°. Tuff rings have lower Hco/Wco ratios that are between 0.01 and 0.04 and lower outer slopes between 3° and 21°.
This study shows that basic shape parameters in combination with slope angle analysis can be used to discriminate among different types of monogenetic volcanoes. The initial eruptive-related morphometric diversity, however prevents correlation of eruption ages with morphometric parameters, or constructing a relative chronology of the monogenetic eruptions. This work provides a better comprehension of the potential evolution of a future eruption and a broader understanding of volcanic hazards on Deception Island.
•Explosive hydromagmatic eruptions represent the main type of post-caldera activity at Deception Island.•Tuff cones and tuff rings were the main type of morphologies recognised.•Shift of hydromagmatic activity due to spatial changes within an actively evolving collapse caldera.•Morphometric analysis and field observations provide a valuable tool for hazard assessment.
The Tierra Blanca Joven (TBJ) eruption from Ilopango volcano deposited thick ash over much of El Salvador when it was inhabited by the Maya, and rendered all areas within at least 80 km of the ...volcano uninhabitable for years to decades after the eruption. Nonetheless, the more widespread environmental and climatic impacts of this large eruption are not well known because the eruption magnitude and date are not well constrained. In this multifaceted study we have resolved the date of the eruption to 431 ± 2 CE by identifying the ash layer in a well-dated, high-resolution Greenland ice-core record that is >7,000 km from Ilopango; and calculated that between 37 and 82 km³ of magma was dispersed from an eruption coignimbrite column that rose to ∼45 km by modeling the deposit thickness using state-of-the-art tephra dispersal methods. Sulfate records from an array of ice cores suggest stratospheric injection of 14 ± 2 Tg S associated with the TBJ eruption, exceeding those of the historic eruption of Pinatubo in 1991. Based on these estimates it is likely that the TBJ eruption produced a cooling of around 0.5 °C for a few years after the eruption. The modeled dispersal and higher sulfate concentrations recorded in Antarctic ice cores imply that the cooling would have been more pronounced in the Southern Hemisphere. The new date confirms the eruption occurred within the Early Classic phase when Maya expanded across Central America.
Hasandağ volcano (Central Anatolia, Turkey) has recently underwent an increase in local seismicity and fumarolic activity since 2013. In the past, this volcano has produced multiple large explosive ...eruptions during the last million years. The Belbaşhanı Pumice is the product of a sub-Plinian to Plinian eruption dated at ~ 417 ± 20.5 ka (
40
Ar/
39
Ar). Here, we present a complete volcanological study including stratigraphy, glass chemistry, pumice morphology, geochronology, and eruption source parameters with the associated uncertainties, to characterize the Belbaşhanı Pumice eruption. The eruption involved a column of 18–29 km in height, with the main dispersal axis towards the northeast. A pumice layer up to ~ 17-m-thick accumulated in proximal deposits along the Belbaşhanı path, and up to 2-m-thick in medial-distal areas (~ 18 km northeast from the vent). The high and tubular vesicularity of the pumice clasts indicates that the Belbaşhanı eruption was predominantly magmatic. The bulk volume of the Belbaşhanı Pumice fallout deposit has been estimated as 0.5 and 8 km
3
(with ~ 2 km
3
being the mean value), which corresponds to Volcanic Explosivity Index (VEI) of at least 4 and up to 6. Both isopach and isopleth maps indicate that the volcanic vent may have been located at the intersection of the Tuz Gölü fault and Ulukışla caldera, within the Hasandağ volcanic complex. The glass composition of Belbaşhanı Pumice confirms that the eruption belongs to the Hasandağ magmatic system. The reconstruction of the Belbaşhanı Pumice eruption represents an essential baseline in providing volcanological constraints for further investigations of tephra fallout hazard assessment in Central Anatolia, especially considering that a new Plinian eruption cannot be ruled out at Hasandağ volcano in the future. The chemical and geochronological datasets presented here could aid in refining tephrochronological correlations, with the goal of synchronizing paleoenvironmental and paleoclimatic records alongside archaeological sites.
The Ilopango caldera is the source of the large Tierra Blanca Joven (TBJ) eruption that occurred about 1.5 ka years ago, between ca. AD270 and AD535. The eruption dispersed volcanic ash over much of ...the present territory of El Salvador, and pyroclastic density currents (PDCs) extended 40 km from the volcano. In this study, we document the physical characteristics of the deposits from all over El Salvador to further constrain the eruption processes and the intensity and magnitude of the different phases of the eruption. The succession of deposits generated by the TBJ eruption is made of 8 units. The eruption started with PDCs of hydromagmatic origin (Unit A0), followed by fallout deposits (Units A and B) that are <15 cm thick and exposed in sections close to the Ilopango caldera (within 10–15 km). The eruption, then, transitioned into a regime that generated further PDCs (Units C–F), these range from dilute to dense and they filled the depressions near the Ilopango caldera with thicknesses up to 70 m. Deposits from the co-ignimbrite plume (Unit G) are the most widespread, the deposits are found in Guatemala, Honduras, Nicaragua, Costa Rica and the Pacific Ocean and cm-thick across El Salvador. Modelling of the deposits suggests that column heights were 29 km and 7 km for the first two fallout phases, and that the co-ignimbrite phoenix plume rose up to 49 km. Volumes estimated for the fallout units are 0.15, 0.8 and 16 km3 dense rock equivalent (DRE) for Unit A, B and G respectively. The PDCs deposits volumes were estimated to be ~0.5, ~3.3, ~0.3 and ~9.1 km3 DRE for Units C, D, E and F, respectively. The combined volume of TBJ deposits is ~30 km3 DRE (~58 km3 bulk rock), indicating that it was one of largest Holocene eruptions from Central America. This eruption occurred while Mayan populations were living in the region and it would have had a significant impact on the areas within tens of kilometres of the vent for many years to decades after the eruption.
•Detailed stratigraphy of the TBJ (Tierra Blanca Joven) eruption•Transport/depositional mechanisms, eruption dynamics and physical parameters•Modelling of the dispersion of products•Local and regional impact on Maya civilization
Deception Island (Antarctica) is the southernmost island of the South Shetland Archipelago in the South Atlantic. Volcanic activity since the eighteenth century, along with the latest volcanic unrest ...episodes in the twentieth and twenty-first centuries, demonstrates that the volcanic system is still active and that future eruptions are likely. Despite its remote location, the South Shetland Islands are an important touristic destination during the austral summer. In addition, they host several research stations and three summer field camps. Deception Island is characterised by a Quaternary caldera system with a post-caldera succession and is considered to be part of an active, dispersed (monogenetic), volcanic field. Historical post-caldera volcanism on Deception Island involves monogenetic small-volume (VEI 2–3) eruptions such forming cones and various types of hydrovolcanic edifices. The scientific stations on the island were destroyed, or severely damaged, during the eruptions in 1967, 1969, and 1970 mainly due to explosive activity triggered by the interaction of rising (or erupting) magma with surface water, shallow groundwater, and ice. We conducted a detailed revision (field petrology and geochemistry) of the historical hydrovolcanic post-caldera eruptions of Deception Island with the aim to understand the dynamics of magma-water interaction, as well as characterise the most likely eruptive scenarios from future eruptions. We specifically focused on the Crimson Hill (estimated age between 1825 and 1829), and Kroner Lake (estimated age between 1829 and 1912) eruptions and 1967, 1969, and 1970 events by describing the eruption mechanisms related to the island’s hydrovolcanic activity. Data suggest that the main hazards posed by volcanism on the island are due to fallout, ballistic blocks and bombs, and subordinate, dilute PDCs. In addition, Deception Island can be divided into five areas of expected activity due to magma-water interaction, providing additional data for correct hazard assessment on the island.
Eruptive activity of individual monogenetic volcanoes usually lasts a few days or weeks. However, their short lifetime does not always mean that their dynamics and structure are simple. Monogenetic ...cones construction is rarely witnessed from the beginning to the end, and conditions for observing their internal structure are hardly reached. We provide high‐resolution electrical resistivity sections (10 m electrode spacing) of three monogenetic cones from northeastern Spain, comparing our results to geological observations to interpret their underground continuation. The 100 m maximum depth of exploration provides information on almost the entire edifices, highlighting the relationships between Strombolian and hydromagmatic deposits in two multiphase edifices. A main observation is a column of distinct resistivity centered on the Puig d'Adri volcano, which we interpret as the eruptive conduit. This method can provide valuable information on the past volcanic dynamics of monogenetic volcanic fields, which has real implications for the forecast of future activity.
Key Points
Electrical resistivity tomography was performed on monogenetic volcanoes
The eruptive conduit of a Strombolian cone was identified
ERT imaging contributes in volcanic forecasting by the identification of hazards
We applied self-potential (SP) and electrical resistivity tomography (ERT) to the exploration of the uppermost part of the substrate geology and shallow structure of La Garrotxa monogenetic volcanic ...field, part of the European Neogene–Quaternary volcanic province. The aim of the study was to improve knowledge of the shallowest part of the feeding system of these monogenetic volcanoes and of its relationship with the subsurface geology. This study complements previous geophysical studies carried out at a less detailed scale and aimed at identifying deeper structures, and together will constitute the basis to establish volcanic susceptibility in La Garrotxa. SP study complemented previous smaller-scale studies and targeted key areas where ERT could be conducted. The main new results include the generation of resistivity models identifying dykes and faults associated with several monogenetic cones. The combined results confirm that shallow tectonics controlling the distribution of the foci of eruptive activity in this volcanic zone mainly correspond to NNW–SSE and accessorily by NNE–SSW Neogene extensional fissures and faults and concretely show the associated magmatic intrusions. These structures coincide with the deeper ones identified in previous studies, and show that previous Alpine tectonic structures played no apparent role in controlling the loci of this volcanism. Moreover, the results obtained show that the changes in eruption dynamics occurring at different vents located at relatively short distances in this volcanic area are controlled by shallow stratigraphical, structural and hydrogeological differences underneath these monogenetic volcanoes.
The Puig de la Banya del Boc volcano is located in the southern sector of the Garrotxa Volcanic Field in the NE of the Iberian Peninsula and is part of the European Cenozoic Rift System. This ...monogenetic volcano was constructed on a hard basement of Paleozoic metamorphic rocks and shows a complex eruptive succession with phreatomagmatic, Strombolian, and effusive phases. Similar to other volcanoes of the same volcanic field, the succession of deposits of the Puig de la Banya del Boc volcano reveals the influence of the substrate, upon which the volcano forms, on eruption dynamics. In this case, the Paleozoic basement and its particular hydrodynamic properties controlled the way in which magma/water interactions occurred throughout the eruption. This volcano is coeval with the Clot de l'Omera, a small maar-type edifice that was emplaced on a conjugate fault, which belongs to the same fault system.
•This volcano is characterized by phreatomagmatic and Strombolian/Hawaiian phases.•The hard basement controlled the way in which magma/water interactions occurred.•The unpredictable behavior of these eruptions makes them of high risk.
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