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  • 1
    Publication Date: 2019-06-30
    Description: The Bransfield Strait is a seismically active extensional rift located between the Antarctic Peninsula and the South Shetland Islands that is forming in continental crust but may be near the transition to seafloor spreading. As part of the BRAVOSEIS project, an international effort focused on the seismological research of submarine volcanoes and rift dynamics in the Bransfield Strait, we deployed a nested, amphibious seismic network in the area. The regional network comprises 15 broadband land seismometers in the South Shetland Islands and the Antarctic Peninsula; 9 broadband OBSs deployed across the Central Bransfield Basin; and 6 hydrophone moorings spanning the rift. It covers an area of 200x100 km2, with an average inter-station distance of ~30 km. Additionally, 15 short-period OBSs were deployed in a tight cluster around Orca volcano, a submarine volcanic edifice south of King George Island. This local network has an aperture of 20 km, with an average inter-station distance of ~4 km. Eight land stations were deployed in February 2018, with the remainder deployed in January 2019. All instruments will be recovered in early 2020. The recorded seismicity will be analyzed using state-of-the-art techniques. The results may shed light on the crustal structure and tectonic regime in the South Shetlands region; elucidate among different theories on the origin of the Bransfield rift; image the location and extent of magma accumulation zones related to submarine volcanic structures; and assess the internal processes that occur in the submarine volcanoes of the Bransfield area.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 2
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    Springer
    In:  EPIC3Springer, 24 p., pp. 281-304, ISBN: 9783031455537
    Publication Date: 2024-01-08
    Description: Calving of iceberg at ice shelves and floating glacier tongues is a poorly understood process, hence a physically motivated calving law is not yet existing. The demands on developing appropriate models for calving is large, as calving rates are needed for large scale ice sheet models that simulate the evolution of ice sheets. Here, we present a new approach for simulating fracture in ice. Our model is based on a finite strain theory for a viscoelastic Maxwell material, as the large simulation time leads to high strains. The fracturing process is simulated using a fracture phase field model that takes into account the elastic strain energy. We conduct simulations for a typical calving front geometry, with ice rises governing the formation of cracks. To represent the stress state adequately, we first conduct a spin-up to allow the viscous contribution to develop before the fracture phase field is computed. The analysis comprises the assessment of the crack path in comparison to observations, the influence of the spin-up, as well as elastic versus viscous strain contributions based on Hencky strain. Additionally, an estimate of released energy based on high resolution optical imagery of a Greenlandic calving front is presented.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
    Format: application/pdf
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  • 3
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    Wiley
    In:  EPIC3PAMM, Wiley, 22(1), ISSN: 1617-7061
    Publication Date: 2023-10-24
    Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Ice shelves are large floating ice masses, that are formed when glaciers are becoming afloat at the margin of ice sheets. One dominating mass loss mechanism of ice shelves is calving, describing the detachment of icebergs at the front. Ice shelves stabilize inland ice glaciers due to buttressing. If the stabilizing effect of an ice shelf vanishes because of disintegration or thinning, the corresponding glacier accelerates resulting in sea level rise.〈/jats:p〉〈jats:p〉To describe calving and disintegration of ice shelves, it is important to investigate fracture propagation in ice. A powerful method in fracture mechanics is the phase field method which is based on Griffith's theory. It approximates cracks in a diffuse manner by using a continuous scalar field. We propose a phase field fracture model for ice considering its characteristic material properties. The material behavior of ice depends on the considered time scales. On short time scales it behaves like a solid and while it acts like a fluid on long time scales, which classifies it as a viscoelastic material of Maxwell type. This has been verified by observations. The phase field method allows us to simulate typical fracture situations of ice shelves in Antarctica and Greenland.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
    Format: application/pdf
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