A. Geyer

Spanish National Research Council | CSIC · Institute of Earth Sciences Jaume Almera

Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica, with more than 20 explosive eruptive events registered over the past two centuries. Recent eruptions (1967, 1969, and 1970) and volcanic unrest episodes (1992, 1999, and 2014–2015) demonstrate that volcanic activity is likely occurring in the future. This i...

Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica, with more than 15 explosive eruptive events registered over the past two centuries. Recent eruptions (1967, 1969 and 1970) and volcanic unrest episodes in 1992, 1999 and 2014–15 demonstrate that the occurrence of future volcanic activity is a valid and pres...

The North Atlantic Oscillation (NAO) is the major atmospheric mode that controls winter European climate variability because its strength and phase determine regional temperature, precipitation and storm tracks. The NAO spatial structure and associated climatic impacts over Europe are not stationary making it crucial to understanding its past evolu...

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...

Antarctica and Zealandia were once-adjacent blocks of Gondwana with a shared magmatic history during the Mesozoic and earlier. This is preserved in (a) shared Palaeozoic and Mesozoic Gondwana plutonism; (b) magmatism associated with syn-Gondwana breakup, including Jurassic-aged dolerite rocks of the Ferrar large igneous province, and igneous intrus...

Geochemistry of volatiles in active volcanoes provides insights into the magmatic processes and evolution at depth, such as magma evolution and degassing, which can be implemented into volcanic hazards assessment. Deception Island is one of the most active volcanoes in Antarctica, with more than twenty explosive eruptions documented over the past t...

Geochemistry of volatiles in active volcanoes provides insights into the magmatic processes and evolution at depth, such as magma evolution and degassing, which can be implemented into volcanic hazards assessment. Deception Island is one of the most active volcanoes in Antarctica, with more than twenty explosive eruptions documented over the past t...

The North Atlantic Oscillation (NAO) is the major atmospheric mode ruling European climate variability during winter and its significance is underpinned by the number of recent studies aimed at reconstructing past NAO variability across different time scales and temporal resolutions. We present a new 2000-year multi-annual, proxy-based, local NAO i...

Deception Island is one of the most active volcanoes in Antarctica, with more than twenty explosive eruptions documented over the past two centuries. Volatiles can provide insights into the magmatic processes and evolution of active volcanoes, which can be implemented into volcanic hazards assessment. Stable isotopes (hydrogen and oxygen) on trappe...

Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica. In the 1988–1989 austral summer, after the most recent eruptive process on the island (1967–1970), monitoring of volcanic activity through geophysical and geodetic techniques was resumed by Spanish and Argentinean scientists. In order to monitor the island'...

Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica, with more than 20 explosive eruptive events registered over the past two centuries. Recent eruptions (1967, 1969, and 1970) and the volcanic unrest episodes that happened in 1992, 1999, and 2014–2015 demonstrate that the occurrence of future volcanic activi...

Abstract The caldera collapse of Deception Island Volcano, Antarctica, was comparable in scale to some of the largest eruptions on Earth over the last several millennia. Despite its magnitude and potential for far-reaching environmental effects, the age of this event has never been established, with estimates ranging from the late Pleistocene to 33...

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. Desp...

Pacific islands are spread over thousands of kilometres of the Pacific Basin and are characterised by similar ecological features but very diverse geologic origins, from steep volcanoes to flat coral atolls. Several climatic phases have been shared across the region within the last 1,000 years. Numerous and abrupt societal and cultural changes duri...

Ash emitted during explosive volcanic eruptions may disperse over vast areas of the globe posing a threat to human health and infrastructures and causing significant disruption to air traffic. In Antarctica, at least five volcanoes have reported historic activity. However, no attention has been paid to the potential socio-economic and environmental...

Conducting long-term hazard assessment in active volcanic areas is of primary importance for land-use planning and defining emergency plans able to be applied in case of a crisis. A definition of scenario hazard maps helps to mitigate the consequences of future eruptions by anticipating the events that may occur. Lanzarote is an active volcanic isl...

EPOS (European Plate Observation System) (https://www.epos-ip.org/) is now established as the only European multidisciplinary and global research infrastructure in Earth Sciences. It integrates several hundred national observatories for the observation and measurement of the internal and dynamic structure of the planet, and in particular in Europe,...

Dykes at the Vicuña Pampa Volcanic Complex, which are mostly basaltic (trachy)-andesite and (trachy)-andesite, are exposed at the base and along the walls of a large depression resulting from intense degradation. Dykes intruding stiff layers (lavas, plugs and necks) are thin, mostly dip>60° and have coherent textures, whereas dykes intruding more c...

Deep-water corals growing in close proximity to the 2011 submarine eruption at Tagoro (El Hierro Island; Canary Archipielago, Spain) have revealed their ability to record the magmatic helium (³He) signal during a period of months prior to the eruption with magmatic ³He/⁴He ratios of 3.6–5.0 RA This is similar to the range of He isotope values (3–10...

Ash emitted during explosive volcanic eruptions can be dispersed over massive areas of the globe, posing a threat to both human health and infrastructures, such as the air traffic. Some of the last eruptions occurred during this decade (e.g. 14/04/2010 - Eyjafjallajökull, Iceland; 24/05/2011-Grímsvötn, Iceland; 05/06/2011-Puyehue-Cordón Caulle, Chi...

Ignimbrites are pyroclastic density current deposits common in explosive volcanism involving intermediate and silicic magmas and in less abundance in eruptions of basaltic central and shield volcanoes. However, they are not widely described in association with monogenetic volcanism, where typical products include lava flows, scoria and lapilli fall...

Conducting long-term hazard assessment in active volcanic areas is of primordial importance for land planning and to define emergency plans able to be applied in case of a crisis. Definition of scenario hazard maps helps to mitigate the consequences of future eruptions by anticipating to the events that may occur. Lanzarote is an active volcanic is...

Understanding how monogenetic volcanic systems work requires full comprehension of the local and regional stresses that govern magma migration inside them and why/how they seem to change from one eruption to another. During the 2011–2012 El Hierro eruption (Canary Islands) the characteristics of unrest, including a continuous change in the location...

The factors controlling the preparation of volcanic eruptions in monogenetic fields are still poorly understood. The fact that in monogenetic volcanism each eruption has a different vent suggests that volcanic susceptibility has a high degree of randomness, so that accurate forecasting is subjected to a very high uncertainty. Recent studies on mono...

BCN Rocks is an application (App) for personal mobile devices (Android and iOS versions) suitable for secondary and high school students as well as people without background in Earth Sciences. The main objective of this App is to learn geology using the city facades and pavements of two emblematic spaces of the city of Barcelona, the Passeig de Grà...

In volcanic areas, the existing stress field is a key parameter controlling magma generation, location and geometry of the magmatic plumbing systems and the distribution of the resulting volcanism at surface. Therefore, knowing the stress configuration in the lithosphere at any scale (i.e. local, regional and plate-scale) is fundamental to understa...

Field exposures of magma chambers tend to reveal contact metamorphic aureoles in the surrounding crust, which width varies from few centimeters to kilometers. The igneous accumulation not only increases the temperature around it, but also weaks its surrounding country rock beyond the brittle-ductile transition temperature. The formation of a ductil...

[EN] Barcelona Rocks is an application for personal mobile devices (Android and iOS versions) suitable for secondary and high school students as well as people without background in Earth Sciences. The main objective of this App is to learn geology using the city facades and pavings of two emblematic spaces of the city of Barcelona, the Passeig de...

Ground deformation has been demonstrated to be one of the most common signals of volcanic unrest. Although volcanoes are commonly associated with significant topographic relief, most analytical models assume the Earth’s surface as flat. However, it has been confirmed that this approximation can lead to important misinterpretations of the recorded s...

Within the context of magma transport processes in a dyke, this paper integrates petrography and thermodynamic modelling together with fluid dynamics to model the melting of the wall rock in three magma dykes at crustal depths from 8 to 19 km. Using this combination we explore the interaction between thermal and mechanical processes during silicic...

Erosional processes (natural or anthropogenic) may partly destroy the relatively small-sized volcanic edifices characteristic of monogenetic volcanic zones, leaving their internal structure well exposed. Nevertheless, the study of these out-crops may be extremely challenging due to restricted accessibility or safety issues. Digital representations...

The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical, and experimental studies. Nonetheless, even...

In the southern winter of 1970, a phreatomagmatic eruption occurred in the northern part of Deception Island (South Shetland Archipelago, Antarctic Peninsula). The eruption, with no eye-witnesses to the event, occurred in the same general area as the 1967 eruption, but with new, more widely distributed vents. Two contrasting groups of craters were...

Deception Island is the most active volcano in the South Shetland Islands and has been the scene of more than twenty identified eruptions over the past two centuries. In this contribution we present the first comprehensive long-term volcanic hazard assessment for this volcanic island. The research is based on the use of probabilistic methods and st...

We report new geophysical observations on the distribution of subsurface structures associated with monoge-netic volcanism in the Garrotxa volcanic field (Northern Spain). As part of the Catalan Volcanic Zone, this Quaternary volcanic field is associated with the European rifts system. It contains the most recent and best preserved volcanic edifice...

Determining the link between shallow structure and volcanism is a topic of interest in Volcanology. We carried out a geophysical study devoted to the characterization of the major structural limits influencing volcanic hydrothermal activity and underground meteoric circulations in La Palma (Canary Islands). Since 1 Ma volcanic activity concentrates...

Morphometry-based dating provides a first-order estimate of the temporal evolution of monogenetic volcanic edifices located within an intraplate monogenetic volcanic field or on the flanks of a polygenetic volcano. Two widely used morphometric parameters, namely cone height/width ratio (H max/W co) and slope angle, were applied to extract chronolog...

The tuff cone of El Golfo on the western coast of Lanzarote (Canary Islands) is a typical hydrovolcanic edifice. Along with other edifices of the same age, it was constructed along a fracture oriented NEE–SWW that coincides with the main structural trend of recent volcanism in this part of the island. We conducted a detailed stratigraphic study of...

Deception Island has been interpreted variously as a classical ring fault caldera, as a tectonically controlled collapse caldera or as a tectonic depression. Review of previous studies combined with new fieldwork has allowed us to obtain a more precise model of the formation and internal structure of the Deception Island caldera. It formed as a res...

Hierro eruption started on 10 October 2011 after an unrest episode that initiated on 17 July 2011. This is the first eruption in the Canary Islands that has been tracked in real time. Although being submarine and not directly observable, the data recorded allowed its reconstruction and to identify its causes and mechanisms. Seismicity, surface defo...

The International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) Commission on Collapse Calderas organized its fourth workshop in the Vulsini Calderas District, Italy (http://www.gvb-csic.es/CCC.htm). Vulsini includes the Bolsena and Latera calderas, formed in the past 0.6 million years. It is a famous type locality where...

Export Date: 21 June 2013, Source: Scopus, Article in Press, :doi 10.1007/s00445-013-0734-1, Language of Original Document: English, Correspondence Address: Kereszturi, G.; Volcanic Risk Solutions, Massey University, Private Bag 11 222, Palmerston North, New Zealand; email: kereszturi_g@yahoo.com

Negatively buoyant jets consist in a dense fluid injected vertically upward into a lighter ambient fluid. The numerical simulation of this kind of buoyancy-driven flows is challenging as it involves multiple fluids with different physical properties. In the case of immiscible fluids, it requires, in addition, to track the motion of the interface be...

The Garrotxa Volcanic Field (northern Spain) is part of the Catalan Volcanic Zone, of the Quaternary volcanic provinces associated with the European rift system. It contains the most recent and better preserved volcanic edifices of the Catalan Volcanic Zone, with 38 monogenetic volcanoes identified in the Garrotxa Natural Park. As in many other mon...

The El Golfo tuff cone is an example of phreatomagmatic edifice, developed in the western coast of Lanzarote (Canary Islands). El Golfo, together with other edifices of the same age, is aligned along a fracture oriented NEE-SWW coinciding with the main lineation of the historic volcanism in this part of the island. In this contribution we present a...

Deception Island is the most active volcano of the South Shetland Islands (Antarctica) with more than twenty eruptions recognised over the past two centuries. The island was formed on the expansion axis of the Central Bransfield Strait and its evolution consists of constructive and destructive phases. A first a shield phase was followed by the cons...

The Benford's Law predicts that the distribution of first digits of real world observations is not uniform, but instead the lower digits (1, 2, and 3) are expected to occur more frequently than the higher digits (....,8,9). It has been shown that the use of Benford's Law may help as an authenticity and validity check on databases and that the first...

Terra Nova, 23, 220–224, 2011AbstractThe Teide–Pico Viejo stratovolcanoes constitute one of the major potentially active volcanic complexes in Europe but have traditionally been considered to be non-explosive and not to represent a significant threat to the island of Tenerife. However, the reconstruction of their eruptive record is still far from c...

The Catalan Volcanic Zone (CVZ), at the NE of the Iberian peninsula, is one of the Quaternary alkaline volcanic provinces of the European rifts system. The CVZ has been active during the last 12Ma. Despite the fact that this volcanism is significant in extension and volume, and that eruptions have also occurred in Holocene times, it is mostly unkno...

It has been suggested that deglaciations have influenced volcanism in several areas around the world increasing productivity of mantle melting and eruptions from crustal magma chambers. However, the connection between glaciations and increased volcanism is not straightforward. Investigation of Ar–Ar, U–Pb, and 14 C ages of caldera-forming eruptions...

Roughly circular depressions known as calderas are distinctive features in volcanic areas (see Figure 1). Current views explain a caldera as the surface expression of a magma chamber's collapsed roof after magma drains elsewhere. Although not all calderas are associated with explosive activity, most major eruptions (i.e., those with a volcanic expl...

Collapse calderas are one of the most important volcanic structures because of their hazard implications, but also because of their high energy potential and their association with mineral deposits of high economic interest. The worldwide Collapse Caldera Database (CCDB) [22], (http://www.GVB-csic.es/CCDB.htm), currently formed by 473 calderas and...

Polygenetic, silicic collapse calderas are common in the central Andes. Here we describe in detail the Cerro Aguas Calientes caldera in NW Argentina, which comprises two caldera-forming episodes that occurred at 17.15 Ma and 10.3 Ma. We analyse the significance of its structural setting, composition, size and the subsidence style of both caldera ep...

Collapse calderas have been analyzed through field studies, analogue models and numerical simulations. Whereas caldera morphology and structure yield information on subsidence mechanisms and geometry of the associated magma chamber, studies of eruptive products address aspects of magma composition and eruption dynamics. During the last decades, gre...

Ignimbrites are common products of explosive volcanism of intermediate and silicic magmas. They also occur in eruptions of composite basaltic volcanoes. However, they have not been described associated with monogentic volcanism yet. Commonly, monogenetic volcanism tends to generate lava flows, scoria and lapilli deposits, and different kinds of PDC...