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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 result of the explosive eruption of basaltic-to-andesitic magmas, mostly as pyroclastic density currents representing in total a bulk volume of the order of 90 km3. Caldera collapse occurred rapidly along a polygonal structural network consisting of several pre-existing major normal faults. These faults, which originated as a result of regional tectonics, controlled pre- and post-caldera volcanism on the island. The formation of the caldera generated a very active geothermal system inside its depression, which is responsible for most of the present-day seismic activity and may also have a significant influence on the observed surface deformation. Our results do not support the hypothesis that there is a large but shallow, active magma chamber beneath the current caldera; instead we suggest that recent eruptions have been fed by small batches of deeper-sourced magmas. The intrusive remains of these eruptions and probably of other minor intrusions that have not reached the surface provide the main heat source that sustains the current geothermal system.
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... It is a composite volcano, with a substantial collapse caldera measuring c. 8.5-10 km in diameter ( Fig. 1a and b). The caldera-forming eruption, with 30-60 km 3 of ejected magma, has been estimated to be comparable in size to some of the largest eruptions occurring on Earth over the past several millennia (e.g., 1883 eruption of Krakatoa) (Martí et al., 2013). ...
... Deception Island magmas range from basaltic to trachydacitic and rhyolitic compositions, defining a distinctive differentiation trend of increasing alkalinity produced by uncommonly high Na 2 O contents (mainly >4 wt% even in basalts; varying between 2 and 8 wt% overall, Fig. 1c) (e.g., Aparicio et al., 1997;Smellie, 2002b;Geyer et al., 2019). The pre-caldera phase was characterized by the construction of a volcanic shield and is represented by the Basaltic Shield Formation (Fig. 1b), in which most of the units correspond to lava flows, Strombolian deposits and palagonitized hyaloclastite breccias (e.g., Smellie, 2001Smellie, , 2002bMartí et al., 2013). The widespread Outer Coast Tuff Formation, formed during the caldera-forming eruption, comprises a thick sequence of massive dense pyroclastic density current deposits, several tens of meters thick and forms an almost continuous outcrop that encircles most of the island (e.g., Smellie, 2001Smellie, , 2002aSmellie, , 2002bMartí et al., 2013) (Fig. 1b). ...
... The pre-caldera phase was characterized by the construction of a volcanic shield and is represented by the Basaltic Shield Formation (Fig. 1b), in which most of the units correspond to lava flows, Strombolian deposits and palagonitized hyaloclastite breccias (e.g., Smellie, 2001Smellie, , 2002bMartí et al., 2013). The widespread Outer Coast Tuff Formation, formed during the caldera-forming eruption, comprises a thick sequence of massive dense pyroclastic density current deposits, several tens of meters thick and forms an almost continuous outcrop that encircles most of the island (e.g., Smellie, 2001Smellie, , 2002aSmellie, , 2002bMartí et al., 2013) (Fig. 1b). The post-caldera phase, which includes the more recent historical eruptions , includes at least 70 dispersed eruptive vents inside the caldera and around the rim (e.g., Baker et al., 1975;Smellie, 2002c;Smellie and López-Martínez, 2002;Martí et al., 2013;Pedrazzi et al., 2020). ...
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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 few centuries. Recent eruptions (1967, 1969, and 1970) and volcanic unrest episodes (1992, 1999, and 2014–2015) demonstrate that volcanic activity will likely occur in the future. Despite this, there has been a considerable increase in the number of scientific bases, tourist activities and air and vessel traffic in the region during the last several decades. The escalation in interest has increased the amount of infrastructure and population numbers exposed to a future eruption. Thus, there is an urgent need to develop an accurate long-term assessment of the volcanic hazard of the island. However, past attempts have always been limited by the incompleteness of the eruptive record. Volcanic ash layers found in marine and lacustrine sediment cores and glaciers outside Deception Island are a fundamental source of information for reconstructing the explosive eruptive record of the volcano. The spatial distribution of the tephra layers, as well as their physicochemical analysis are invaluable for determining the size and explosiveness of past eruptive events, as well as for assessing the extent and impact of their related hazards (e.g., ash fall out). In order to overcome the dispersion of existing data among numerous publications and to facilitate the analysis of available information on tephra layers sourced in Deception Island, we present the DecTephra (Deception Island Tephra Record) database. The current database version contains 362 tephra layers (including cryptotephras) located at sites up to 3115 km distant from the island. For each tephra layer, the database includes: (i) the location and simple description of the sampling site; and (ii) the key petrologic and geochemical features of each tephra layer. A preliminary analysis of the information contained in the DecTephra database (e.g., magma composition, explosiveness, eruptive recurrence, etc.), validates it as a key tool for evaluating past explosive activity of the volcano. In addition, it can function as a valuable resource for paleoenvironmental and paleoclimatic studies requiring tephrostratigraphical and tephrochronological control at local and regional scales. DecTephra also has the potential to help to assess the contribution of volcanic forcing to Holocene climate variability in the Southern Hemisphere.
... It consists of a composite volcano, whose central part is occupied by a c. 8.5 × 10 km collapse caldera, elongated in NW-SE direction (Fig. 1a). The caldera-forming eruption, with 30-60 km 3 of erupted magma (dense rock equivalent), has been estimated to be comparable in size to some of the largest eruptions occurring on Earth over the past several millennia (e.g., 1883 Krakatoa eruption) (Martí et al., 2013). Port Foster, the sea-flooded part of the caldera depression, has smaller dimensions (c. ...
... Previous to the caldera collapse, volcanic activity led to the formation of multiple shoaling seamounts and a main subaerial volcanic edifice (Fig. 2b). During the caldera-forming event, a several tens of meters thick sequence of pyroclastic density current deposits, known as the Outer Coast Tuff Formation (OCTF) was emplaced (Martí et al., 2013;Smellie, 2001 (Fig. 2a and b). Post-caldera eruptive events, predominantly located along the structural borders of the caldera and the interior of Port Foster (Fig. 1b), have mainly consisted of hydromagmatic eruptions with variable intensity and explosivity degree mostly depending on the amount and provenance of water (i.e., aquifer, sea, and/or ice/snow melting) that interacted with the rising or erupting magma (e.g., Baker et al., 1975;Pedrazzi et al., 2014Pedrazzi et al., , 2018Pedrazzi et al., , 2020Smellie, 2002b). ...
... The basin infilling comprises three seismic units A, B, and C, from older to younger (Rey et al., 1995(Rey et al., , 1997, separated by unconformities interpreted to be individual deformation events that disturbed the geometry of the sedimentary materials ( Fig. 3d and e) (Kowalewski et al., 1990;López-Martínez and Serrano, 2002;Rey et al., 1995Rey et al., , 1997. Unit A is interpreted as the intra-caldera facies of the OCTF deposited during the caldera-forming eruption (e.g., Martí et al., 2013;Rey et al., 2002). It gently dips to the south-west and is overlain by two major post-caldera sedimentary units B and C, both divided into several sub-units ( Fig. 3d and e). ...
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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 is of special concern for scientists, logistic personnel, and tourists, since the South Shetland Islands are an important tourist destination and host numerous year-round and seasonal scientific stations and base camps. Significant efforts have been made to understand the complex magmatic and volcanic evolution of Deception Island with special interest on its subaerial part. However, studies on submerged volcanic cones within Port Foster, the sea-flooded part of Deception Island's caldera depression, are comparatively scarce. Here, we provide a full characterization of Stanley Patch volcano, the largest of these volcanic edifices. Estimated morphometric parameters based on new multibeam bathymetric data, supported by petrographic and chemical observations from rock samples collected on the crater rim, reveal that Stanley Patch volcano grew in a subaerial environment. This result, combined with previous findings and new sedimentological evidence from our ultra-high resolution seismic profiles, allow to further detail the island's geologic evolution since the caldera collapse. We conclude that the complete flooding of Port Foster could have only occurred after the formation of Stanley Patch volcano, i.e. during the last ~2000 years, and in a time period of a few days or less.
... The Deception Island lavas are moderately to highly porphyritic and only some of the mafic lavas are aphyric. Olivine and augite are common in the basaltic rocks, whereas plagioclase, orthopyroxene and augite dominate in the andesites and dacites (Weaver et al. 1979;Martí et al. 2013). In Deception Island lavas, olivine with forsterite (Fo) contents ranging from 36 to 85 occurs in basalts, andesites and dacites (Weaver et al. 1979;Martí et al. 2013). ...
... Olivine and augite are common in the basaltic rocks, whereas plagioclase, orthopyroxene and augite dominate in the andesites and dacites (Weaver et al. 1979;Martí et al. 2013). In Deception Island lavas, olivine with forsterite (Fo) contents ranging from 36 to 85 occurs in basalts, andesites and dacites (Weaver et al. 1979;Martí et al. 2013). Plagioclase compositions with anorthite (An) contents ranging from 23 to 43 were determined in the Deception Island lavas, and glass compositions range from basaltic to andesitic (Martí et al. 2013). ...
... In Deception Island lavas, olivine with forsterite (Fo) contents ranging from 36 to 85 occurs in basalts, andesites and dacites (Weaver et al. 1979;Martí et al. 2013). Plagioclase compositions with anorthite (An) contents ranging from 23 to 43 were determined in the Deception Island lavas, and glass compositions range from basaltic to andesitic (Martí et al. 2013). Clinopyroxene-glass barometry suggests crystallization pressures of 150-200 MPa, which corresponds to a depth of 4-6 km (Martí et al. 2013). ...
... 3D geological formation using RGB camera. Deception Island is a complex volcanic system formed as a result of the explosive eruption of basaltic-to-andesitic magmas 21 . Among its multiple structures and stratigraphy, we surveyed the Murature formation, a consolidated andesitic lapilli tuff 22 . ...
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Antarctica plays a fundamental role in the Earth's climate, oceanic circulation and global ecosystem. It is a priority and a scientific challenge to understand its functioning and responses under different scenarios of global warming. However, extreme environmental conditions, seasonality and isolation hampers the efforts to achieve a comprehensive understanding of the physical, biological, chemical and geological processes taking place in Antarctica. Here we present unmanned aerial vehicles (UAVs) as feasible, rapid and accurate tools for environmental and wildlife research in Antarctica. UAV surveys were carried out on Deception Island (South Shetland Islands) using visible, multispectral and thermal sensors, and a water sampling device to develop precise thematic ecological maps, detect anomalous thermal zones, identify and census wildlife, build 3D images of geometrically complex geological formations, and sample dissolved chemicals (< 0.22 µm) waters from inaccessible or protected areas.
... The 58 samples from Bransfield Strait are dominantly subalkaline basalt, basaltic andesite, and basaltic trachyandesite, with a smaller number of alkaline basalt and tephrite samples restricted to the eastern portion of the basin (Figure 4; Fretzdorff et al., 2004;Keller et al., 2002;Martí et al., 2013). A subset of samples are depleted in LREE and other highly incompatible elements and lack a negative Nb-Ta anomaly, causing them to plot near the 3Tb apex on the Th-3Tb-2Ta diagram within the region occupied by D-MORB. ...
... Port Foster bay, which opens onto the sea through the narrow strait of Neptunes Bellows, occupies the central part of the island and corresponds to the sea-flooded part of the caldera depression. Volcanic activity occurring after the caldera-forming event, which includes the recent historical eruptions ( Fig. 1), comprises several tens of scattered eruptive vents across the whole island (e.g., Martí et al., 2013). Within Port Foster, a submarine volcanic axis composed of several volcanic cones can be distinguished (Rey et al., 1995;Somoza et al., 2004). ...
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Deception Island is amongst the most active volcanoes in the Southern Ocean, with over 20 explosive eruptions in the last ca. 200 years. The eruption that formed the caldera at Deception Island occurred 3980 ± 125 calendar years Before Present, and it is the largest eruptive event documented in Antarctica during Holocene. Since then, post-caldera volcanic activity has comprised many scattered eruptive vents across the island. Mortality of benthic organisms has been reported during the most recent eruptions occurred on the island, in 1967, 1969, and 1970 Common Era (CE), with very low abundances of organisms during the 1967–1973 CE period. Within the sea-flooded part of the caldera depression, named Port Foster, a submarine volcanic axis with several volcanic cones is observed. An interdisciplinary team sampled the best morphologically preserved volcanic edifice within Port Foster, the so-called Stanley Patch. Geophysical data traced the volcano and characterized its morphology and inner structure. Underwater scuba sampling allowed to acquire sediment and rock samples, photographs and video images of the benthic organisms and seascape. Morphology of Stanley Patch cone and textural characteristics of the collected pyroclastic rocks indicate that the volcanic edifice was originated during an explosive eruption. Furthermore, the lack of palagonitization, quenched pyroclast margins, and hyaloclastite deposits indicate that this cone has formed on-land, before the caldera floor became inundated by the seawater, highlighting the complex intra-caldera evolution of Deception Island. A sediment core from the crater was collected for sedimentological, and geochemical analysis. Antarctic climate and seasonal sea ice, together with organic degradation due to high sedimentation rates, explain the low total organic carbon data measured. The volcanic history of the island has probably avoided the development of a stable benthic community over time, similar to other Antarctic shallow communities. Moreover, the current geomorphological conditions still shape different benthic communities than in the surrounding coastal ecosystems. Stanley Patch, and the whole Port Foster, provide a natural laboratory for benchmarking the reestablishment of benthic communities on a volcanic-influenced shallow marine environment, offering relevant data for future studies evaluating global climate change effects on the Antarctic seabed.
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Deception Island (South Shetland Islands, Antarctica) is an active volcano characterized by a moderate level of seismic activity, dominated by long-period seismicity related to hydrothermal processes in a shallow aquifer. Nevertheless, in the last few decades the volcano has undergone at least three episodes of seismic unrest, in 1992, 1999, and 2015. During these episodes, the pattern of seismicity changed, and swarms of volcano-tectonic earthquakes with hundreds of events in time spans of a few months were detected. These episodes are interpreted as consequences of magmatic intrusions. However, the seismic series display significant differences that lead us to think that the processes initiating the series are not exactly the same in all cases. The 1999 series comprised mostly small-magnitude earthquakes, produced regularly during 1.5 months, and located at shallow depths (<4 km) within the caldera, mostly along a WSW-ENE trend that parallels the Bransfield rift. No precursory seismic activity was reported, and a few months after the series onset the seismicity was back to normal levels. The 2015 series included earthquakes with larger magnitudes, occurring during 5 months in temporal clusters separated by aseismic periods. They were located at deeper levels (<10 km) with epicenters distributed all around Deception Island, at distances up to 30 km. Additionally, distal (~35 km) VT seismicity was reported SE of Livingston Island months before the 2015 series onset, and the seismicity at Deception Island remained anomalously high during a few years. Taking into account the limited data available for the 1992 unrest, we conclude that the 1992 and 1999 series were produced by shallow, short-lived, small-volume (~4·10⁴ m³) intrusions that affected the shallowmost part of the volcanic edifice. On the contrary, the 2015 series was consequence of a deep, long-lasting intrusion that involved a larger volume of ~5·10⁶ m³ (in the range of a VEI 2 eruption) and modified the stress field of the whole volcanic edifice.
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The Deception Island (Archipelago of the Shetland of the South, Antártida) is an active seismo-volcanic area in the Antarctic continent. The last and recent eruptive period in 1967, 1969, 1970, and the high frequency of low magnitude earthquakes demonstrate it. The island is in a complex geodynamic setting that establishes SO-NE and NNO-SSE the more important directions of tectonic control, however is not known how the complex geometric organization of fracture networks and faults affects in the distribution of the volcanism and the seismicity in the island. In order to study such effect, in this work a 1:25000 map of the morphologic lineaments is prepared, from a bibliographical synthesis, morphometric analysis of the relief and aerial image processing. The result is validated by means of comparison with a fracturation model of the island. In order to find an structure in the lineament patterns on this map their fractal aggregation and occurrence have been analyzed. The aggregation has been characterized according to a model of Levy-Lee with exponent D, detecting three behaviours in the azimuthal distribution of the fractal dimension: D<1,5, D = 1,5, and D> 1.5, that allow to differentiate six sectors on the island. The space occupation of the fractures has been characterized by means of the estimation of the fractal covering dimension Do which allowed to distinguish the areas in which these tend to distribute uniformly (greater values of Do = 1,62 in NE of the island) or clustered (lower values of Do = 1,39 in zone SW). The joint evaluation of geographic disposition of the zones with similar fractal aggregation and occurrence characteristics has allowed establishing a subdivision in zones where the morphology of the lineament patterns bucket of similar way. The comparison of this zoning with the volcanism typology and/or recent activity allows to establish a possible relation between the type of volcanic activity and the complexity of the pattern in which it happens.
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This paper reviews the recent seismic studies carried out at Deception Island, South Shetland Islands, Antarctica, which was monitored by the Argentinean and Spanish Antarctic Programs since 1986. Several types of seismic network have been deployed temporarily during each Antarctic summer. These networks have consisted of a variety of instruments, including radio-telemetered stations, autonomous digital seismic stations, broadband seismometers, and seismic arrays. We have identified two main types of seismic signals generated by the volcano, namely pure seismo-volcanic signals, such as volcanic tremor and long-period (LP) events, and volcano-tectonic (VT) earthquakes. Their temporal distributions are far from homogeneous. Volcanic tremors and LP events usually occur in seismic swarms lasting from a few hours to some days. The number of LP events in these swarms is highly variable, from a background level of less than 30/day to a peak activity of about 100 events/h. The occurrence of VT earthquakes is even more irregular. Most VT earthquakes at Deception Island have been recorded during two intense seismic crises, in 1992 and 1999, respectively. Some of these VT earthquakes were large enough to be felt by researchers working on the island. Analyses of both types of seismic events have allowed us to derive source locations, establish seismic source models, analyze seismic attenuation, calculate the energy and stress drop of the seismic sources, and relate the occurrence of seismicity to the volcanic activity. Pure seismo-volcanic signals are modelled as the consequence of hydrothermal interactions between a shallow aquifer and deeper hot materials, resulting in the resonance of fluid-filled fractures. VT earthquakes constitute the brittle response to changes in the distribution of stress in the volcanic edifice. The two VT seismic series are probably related to uplift episodes due to deep injections of magma that did not reach the surface. This evidence, however, indicates the high potential for future volcanic eruptions at Deception Island.
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