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  • 1
    Online Resource
    Online Resource
    Spatial and temporal volcanotectonic evolution of Santorini volcano, Greece
    Springer Science and Business Media LLC ; 2022
    In:  Bulletin of Volcanology Vol. 84, No. 6 ( 2022-06)
    Details
    In: Bulletin of Volcanology, Springer Science and Business Media LLC, Vol. 84, No. 6 ( 2022-06)
    Abstract: Volcanic and tectonic activities in the Aegean region have controlled the evolution of Santorini volcano, including changes in the shape and size of the island through time. Previous studies associate much of the island’s volcanic activity with the presence of regional faults, but a comprehensive volcanotectonic study that clarifies the relationship between dyking and faulting in the island has not been made. Here we present a detailed structural analysis focused on the northern caldera wall of Santorini, where numerous dykes and faults outcrop and can be studied in the mesoscale. To augment our discussion of dyke and fault interactions, we combine previous volcanological and geophysical observations with our structural analysis to report the volcanotectonic evolution of the northern part of the island and design a conceptual spatial-temporal model. We mapped 91 dyke segments and 15 faults and classified the latter, where possible, with respect to their observed or recorded kinematics, their size, and the active stress field under which they were formed based on prior geophysical data. We relate our observations to a mechanical unconformity within the northern caldera wall. Our field observations, coupled with previous numerical, geophysical, and volcanological studies, offer insights on the interaction between dykes and faults and indicate the conditions under which the faults facilitated magma emplacement, or not, during the volcano’s activity. Our analysis attempts to answer an essential question: under what conditions do crustal faults facilitate or inhibit magma propagation to the surface, with application to the island of Santorini.
    Type of Medium: Online Resource
    ISSN: 1432-0819
    URL: Article
    DOI: 10.1007/s00445-022-01566-4
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 1458483-9
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  • 2
    Online Resource
    Online Resource
    Historical accounts provide insight on the geological evolution of the 20th century eruptions at Santorini volcano, Greece
    Springer Science and Business Media LLC ; 2023
    In:  Bulletin of Volcanology Vol. 85, No. 12 ( 2023-11-04)
    Details
    In: Bulletin of Volcanology, Springer Science and Business Media LLC, Vol. 85, No. 12 ( 2023-11-04)
    Abstract: The 20th century eruptions of the Santorini volcano in Greece are the most recent activity of the volcano’s long lifespan. While the different eruptions taking place between 1925 and 1950 have traditionally been considered to exhibit similar eruptive styles, aspects of their evolution and precise information related to the individual eruption dynamics were poorly constrained. This study collates field reports and historical accounts, mainly from the Greek national scientific committee, which was assigned to study the volcanic activity in Nea Kameni Island with recent field campaigns. This analysis provides further insight into these eruptions and attempts to unravel the timing and style of explosive and effusive episodes that took place. Reconstruction of the recent geological evolution and of the eruptive history allow a more complete description of the eruption dynamics and associated unrest. These include fumarolic behaviour, explosion intensity, direction and volume of the lava flows, eruption duration, vent morphological changes (such as craters, domes, and horseshoe ramparts), textural characteristics and lava morphologies, as well as surface fracturing. Specific features related to first-hand accounts of the eruptions and associated products, in conjunction with our in situ post-eruptive geological study, allow an improved reconstruction of activity, both prior to and during the historical eruptions, which contributes to understanding the development of the eruption and enhances the forecast of potential future eruptions from patterns of precursory activity.
    Type of Medium: Online Resource
    ISSN: 1432-0819
    URL: Article
    DOI: 10.1007/s00445-023-01681-w
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 1458483-9
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  • 3
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    Online Resource
    Dyke to sill deflection in the shallow heterogeneous crust during glacier retreat: part I
    Springer Science and Business Media LLC ; 2023
    In:  Bulletin of Volcanology Vol. 85, No. 12 ( 2023-11-27)
    Details
    In: Bulletin of Volcanology, Springer Science and Business Media LLC, Vol. 85, No. 12 ( 2023-11-27)
    Abstract: Dykes and sills occupy Mode I (extension), Mode II (shear), or hybrid mode fractures and most of the time transport and store magma from deep reservoirs to the surface. Subject to their successful propagation, they feed volcanic eruptions. Yet, dykes and sills can also stall and become arrested as a result of the crust’s heterogeneous and anisotropic characteristics. Dykes can become deflected at mechanical discontinuities to form sills, and vice versa. Although several studies have examined dyke propagation in heterogeneous and anisotropic crustal segments before, the conditions under which dykes propagate in glacial-volcanotectonic regimes remain unclear. Here, we coupled field observations with 2D FEM numerical modelling to explore the mechanical conditions that encourage (or not) dyke-sill transitions in volcanotectonic or glacial settings. We used as a field example the Stardalur cone sheet-laccolith system, which lies on the Esja peninsula, close to the western rift zone, NW of the southern part of the Icelandic rift. The laccolith is composed of several vertical dykes that transition into sills and form a unique stacked sill ‘flower’ structure. Here, we investigate whether the Stardalur laccolith was formed under the influence of stresses caused by glacial retreat due to thickness variations (0–1 km) in addition to regional and local tectonic stresses (1–3 MPa extension or compression) and varied magma overpressure (1–30 MPa), as well as the influence of the mechanical properties of the lava/hyaloclastite contact. Our results show that the observed field structure in non-glacial regimes was formed as a result of either the mechanical (Young’s modulus) contrast of the lava/hyaloclastite contact or a compressional regime due to pre-existing dykes or faulting. In the glacial domain, the extensional stress field below the ice cap encouraged the formation of the laccolith as the glacier became thinner (subject to a lower vertical load). In all cases, the local stress field influenced dyke to sill deflection in both volcanotectonic regimes.
    Type of Medium: Online Resource
    ISSN: 1432-0819
    URL: Article
    DOI: 10.1007/s00445-023-01684-7
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 1458483-9
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  • 4
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    Online Resource
    Forecasting magma-chamber rupture at Santorini volcano, Greece
    Springer Science and Business Media LLC ; 2015
    In:  Scientific Reports Vol. 5, No. 1 ( 2015-10-28)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 5, No. 1 ( 2015-10-28)
    Abstract: How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily cause an eruption but produces a net volume change that can be measured geodetically by inversion techniques. Using continuum-mechanics and fracture-mechanics principles, we calculate the amount of magma contained at shallow depth beneath Santorini volcano, Greece. We demonstrate through structural analysis of dykes exposed within the Santorini caldera, previously published data on the volume of recent eruptions and geodetic measurements of the 2011–2012 unrest period, that the measured 0.02% increase in volume of Santorini’s shallow magma chamber was associated with magmatic excess pressure increase of around 1.1 MPa. This excess pressure was high enough to bring the chamber roof close to rupture and dyke injection. For volcanoes with known typical extrusion and intrusion (dyke) volumes, the new methodology presented here makes it possible to forecast the conditions for magma-chamber failure and dyke injection at any geodetically well-monitored volcano.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/srep15785
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2015
    detail.hit.zdb_id: 2615211-3
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  • 5
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    Online Resource
    Volcanotectonics: the tectonics and physics of volcanoes and their eruption mechanics
    Springer Science and Business Media LLC ; 2022
    In:  Bulletin of Volcanology Vol. 84, No. 8 ( 2022-07-08)
    Details
    In: Bulletin of Volcanology, Springer Science and Business Media LLC, Vol. 84, No. 8 ( 2022-07-08)
    Abstract: The physical processes that operate within, and beneath, a volcano control the frequency, duration, location and size of volcanic eruptions. Volcanotectonics focuses on such processes, combining techniques, data, and ideas from structural geology, tectonics, volcano deformation, physical volcanology, seismology, petrology, rock and fracture mechanics and classical physics. A central aim of volcanotectonics is to provide sufficient understanding of the internal processes in volcanoes so that, when combined with monitoring data, reliable forecasting of eruptions, vertical (caldera) and lateral (landslide) collapses and related events becomes possible. To gain such an understanding requires knowledge of the material properties of the magma and the crustal rocks, as well as the associated stress fields, and their evolution. The local stress field depends on the properties of the layers that constitute the volcano and, in particular, the geometric development of its shallow magma chamber. During this decade an increasing use of data from InSAR, pixel offset and structure-from-motion, as well as dense, portable seismic networks will provide further details on the mechanisms of volcanic unrest, magma-chamber rupture, the propagation of magma-filled fractures (dikes, inclined sheets and sills) and lateral and vertical collapse. Additionally, more use will be made of accurate quantitative data from fossil and active volcanoes, combined with realistic numerical, analytical and machine-learning studies, so as to provide reliable models on volcano behaviour and eruption forecasting.
    Type of Medium: Online Resource
    ISSN: 1432-0819
    URL: Article
    DOI: 10.1007/s00445-022-01582-4
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 1458483-9
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