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Thesis University of Iceland > Verkfræði- og náttúruvísindasvið > Meistaraprófsritgerðir - Verkfræði- og náttúruvísindasvið >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/5569

Title: 
  • is Crustal conductivity and distribution of melt beneath the Krafla caldera, N-Iceland inferred from magnetotelluric data
Other Titles: 
  • is Rafleiðni jarðskorpunnar og kvika undir Kröfluöskjunni á norðanverðu Íslandi samkvæmt magnetótellúrískum mælingum
Abstract: 
  • is

    Subsurface resistivity structure across the divergent plate boundary of Iceland is
    characterized by thin, intermittent near-surface high conductivity layers associated with
    geothermal alteration and a thick, mid-crustal conductor deepening away from the plate
    boundary. In addition, one-dimensional magnetotelluric (MT) models of the Krafla central
    volcano have revealed two anomalous, updoming zones of high conductivity beneath the
    Krafla caldera overlapping partly shear wave shadow zones interpreted as areas of melt
    accumulation during the 1974-1989 rifting episode. To further constrain the extent of the
    updoming conductors and elucidate their relationship with the lower crustal conductor as
    well as near surface anomalies two-dimensional magnetotelluric inversions were
    conducted along two east-west profiles across the Krafla caldera. The northern profile
    which crosses both shear-wave shadow zones reveals a single updoming conductor within
    the western zone suggesting that the northern boundary of the eastern zone is located just
    south of the profile. Sensitivity tests indicate that the dimensions of the updoming
    conductor (0.5 – 2 km wide and 4 – 5 km high) are in a good agreement with seismic and
    geodetic data. The conductive dome connects with a near-surface conductive layer, at less
    than 500 m, which correlates with surface geothermal manifestations and the mid crustal
    connector, at 6-16 km depth. The top of the deeper conductor correlates fairly well with the
    brittle-ductile crustal boundary. Although joint interpretation of magnetotelluric data with
    other geophysical data further illuminates the geometrics of the shallow magma system of
    Krafla the percentage of partial melt within the mid-crustal conductor remains unknown.

Accepted: 
  • Jun 8, 2010
URI: 
  • http://hdl.handle.net/1946/5569


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