Research Projects

In 1996 the personnel of the Geophysics Division of the Science Institute included six research scientists and three technicians supported by the Institute budget. The Division also provides research facilities for two of the teaching staff at the Faculty of Science of the University. Several other scientists, engineers and research assistants were employed at the Division during the year, either full-time or part-time. These positions were funded through grants, collaborative projects or consulting work.

The research projects of the Geophysics Division reflect to a considerable extent the unique geographical and geological position of Iceland, especially with regard to its active volcanism and glaciers. They may be classified roughly as follows:

• Seismology of tectonic and volcanic earthquakes; horizontal and vertical crustal movements; studies of crustal structure by natural and man-made seismic waves as well as by gravity and magnetic methods; studies of mantle inhomogeneity.

• Research in glaciology including measurements of ice cap surface and bedrock topography, glacier mass balance, hydrology of glacial rivers, surges and other glacier movements, glacier-volcano interaction, climate effects, and many related topics.

• Geomagnetism, including the operation of a geomagnetic observatory and three Japanese auroral observatories by a separate Upper Atmosphere Section of the Division. Paleomagnetic measurements on basalt lavas are also carried out at the Division.

• Research on groundwater and glacier ice through measurements of hydrogen and oxygen isotope ratios by the Division's mass spectrometer. This research includes participation in multinational drilling projects on the Greenland ice cap which have yielded much information on atmospheric conditions in the Late Quaternary. The Division is also taking part in various studies involving radiocarbon dating.

The following research projects were active in the year 1996:

Įrny Erla Sveinbjörnsdóttir

• Groundwater
  Isotopic measurements (18O, D, 13C, 14C) are used to trace groundwater flow, map drainage areas and groundwater systems and for age estimations. Isotopic measurements on geothermal water give valuable information on processes within the systems.

• Age determination by 14C (AMS)
  Sample preparation and the 13C/12C measurements are performed at Science Institute (SI), whereas the 14C concentration is measured at the AMS laboratory in Aarhus, Denmark. Emphasis has been put on research involving late glacial time and the beginning of Holocene, the eruption history of the country and groundwater.
• Paleoclimate
  International research on deep ice cores from Greenland to study paleoclimate in the North Atlantic. Stable isotopes of oxygen and deuterium are measured at the SI, especially in samples that need precision, e.g. when the deuterium excess is determined and when annual variations are studied.

• The crustal thickness of Iceland
  Recent refraction measurements, using 3-component, digital seismographs deployed on longer and denser profiles than before have generated a new image of the crustal structure of Iceland which prompted reinterpretation of older data. The crust is thickest (35 km) beneath the Tertiary provinces and thins towards the volcanic zones, where it is 19-22 km thick. An increase in crustal thickness is also observed towards the center of the Iceland hot spot, beneath Vatnajökull. This project is carried out in cooperation with numerous Icelandic and foreign scientists. The results are of interest to those studying mantle plumes and oceanic ridges.
• Locating magma chambers within active central volcanoes
  Magma chambers play an important role in the evolution of individual volcanic systems and crustal formation. Mapping crustal magma chambers within the 30 active volcanic systems of Iceland is a fundamental prerequisite to hazard assessment of these volcanoes.

• Glacier mapping
  Detailed mapping of the ice surface and bedrock topography of ice caps and glaciers using radio-echo sounding. The maps are used for research on ice movement, definition of ice and water drainage basins, subglacial volcanism and geomorphology. Carried out in cooperation with the National Power Company and the Public Roads Administration.

  Radio echo soundings are also being employed in studies of the internal structure of ice caps, e.g. by mapping tephra layers in the ice (used in modelling of the ice flow regime), and by mapping the thermal regime of glaciers in Spitzbergen (in collaboration with the Universities in Bergen and Oslo).

• Surges
  Research on glacier surges: measurements to define surge type glaciers in Iceland; the effect of surges on ice movement and water flow in glaciers. Cooperation with the National Power Company.
• Jökulhlaups
  Research on jökulhlaups from subglacial lakes of geothermal and volcanic origin. The jökulhlaup from Grimsvötn (Vatnajökull) in 1996. Cooperation with the Public Roads Administration.
• Glacier mass balance
  Studies on the mass balance, ice movement and runoff from glaciers. Connections between mass balance and meteorological variables; the effect of climate change on mass balance. Funded by the European Union and carried out in collaboration with Prof. J. Oerlemans of Utrecht University and Prof. M. Kuhn, University of Innsbruck as well as with the National Power Company.
• Models
  Model calculations of the flow regime of the Vatnajökull ice cap. Collaboration with Dr. R. Hindmarsh, British Antarctic Survey, Campbridge.

• Structure of the crust and mantle under Iceland
  Velocity structure of the crust and upper mantle are mapped with explosion and earthquake seismology. The velocity structure can be transposed (with some uncertainty) into thermal structure, constraining an image of the slowest and hottest region under Iceland, the mantle plume. We look for the hottest region within the plume and under the volcanic zones, where the mantle partially melts. They correspond to the furnace where all primary crustal material that makes up Iceland is produced.
• Mantle anisotropy
  We measure splitting of teleseismic SKS-waves recorded in Iceland. The source of splitting is interpreted to be anisotropic upper mantle under Iceland. The anisotropy is interpreted to be caused by mantle flow, from the plume and/or large scale plate tectonics.
• Relation between volcanism and seimecity in the Vatnajökull region
  The status and development of the seismicity of the Vatnajökull region casts light on the volcanism of the area. The monotoring and analysis of the seismicity of the area can reveal precursors to volcanic eruptions, as well as being one of the best methods to monitor subglacial eruptions.

• Paleomagnetism
  Research on magnetic remanence directions in Icelandic Neogene basalt lava sequences. The results are of use in local stratigraphic mapping and in recording the history of the geomagnetic field.
• Aeromagnetic surveys
  Processing and geological interpretation of magnetic field measurements from aircraft, carried out over parts of the shelf area south and west of Iceland in 1990-1992, and over the Reykjavik region in 1993.
• History of science in Iceland
  Collection of historical material on foreign expeditions to Iceland, especially in the late 19th century, and on other aspects of the development of research and teaching of natural sciences in the 20th century.

• Subglacial volcanism
  Physical nature of subglacial volcanism, in particular the interaction of volcanoes and the overlying glaciers using data from the 1996 eruption in Vatnajökull and earlier eruptions. Heat transfer between magma and ice, effects on ice flow, effects of the glacier on the form of volcanic structures.
• Structure of volcanoes
  Studies of the structure and thermal state of volcanic centres and geothermal areas using gravimetry and magnetics. Size and structure of volcanoes and their relationship with crustal thickness and thermal state. Data from surveys on the volcanoes Grķmsvötn, Mżrdalsjökull, Bįršarbunga and Öręfajökull.
• Effects of surges on runoff from glaciers
  During glacier surges the surface becomes heavily crevassed and the contact area between ice and air increases. This may cause increased melting due to meteorological processes. Data on river discharge and glacier topography for the surge of Brśarjökull in 1963-64 are used in the study. Cooperation with the National Power Company.

• Crustal movements and geodynamics
  Direct measurements of the movements of the Earth's crust are used to constrain models of physical properties and processes within the Earth. Several measuring techniques are used to determine the movements, s.a. GPS-geodesy, satellite radar (SAR) interferometry, sea-level monitoring, and electromagnetic distance measurements.
• Earthquakes and tectonism
  The source processes of earthquakes are studied by investigating the waves they produce and the surface manifestation of the causative faults. The focal mechanisms of earthquakes are determined as well as parameters s.a. the magnitude and the seismic moment. The area of study is the seismic belt of the Mid-Atlantic Ridge, including the active tectonic zones of Iceland. The results are of fundamental importance for estimates of seismic risk.
• Internal structure and dynamics of volcanoes
  Seismographs are used to give information on the structure and activity of volcanoes. Seismic activity in the roots of a volcano gives an indication of its physical state, magma pressure and magma movements. Earthquake sources show where the crust is brittle, and seismic waves carry information on magma chambers and molten material.