RD&D-Programme 2004 - SKB

Another goal of the project “Basal conditions and hydrology of continental ice sheets” is
to describe the ice sheet’s subglacial hydrology and the hydrological features of subglacial
channels and their importance for pressures and flows, as well as to study how they are formed.
Numerical modelling is combined with field studies in the project. The field studies include
measurements on Storglaciären /21-20, 21-21/. The possibilities of utilizing the Greenland Ice
Sheet as an analogue are also being explored. Scandinavian glacial land forms also reveal a
great deal about subglacial conditions, in particular during deglaciation. A compilation of paleogeohydrological
data was started in 2003 and is planned to be completed during 2004. These
data, combined with the results of ice sheet modelling, should result in a better understanding of
subglacial hydrology. An example is co-interpretation of esker orientations and modelled basal
meltwater flows, ice thickness and ice movement.
The ice sheet varies greatly in size during a glaciation. This means that the extent of areas with
warm-based conditions, and thereby an active subglacial hydrology, will also vary to a high
degree. Up to now, very little has been done to examine these temporal and spatial variations
during the most recent ice age. Another goal of the project is therefore to devise a wellcalibrated
model simulation of the Weichselian ice sheet, based on our geological knowledge
of the most recent ice age. With the aid of better input data, calibration data and validation data
compared with previous studies, useful information will be obtained on the basal thermal and
hydrological conditions of the ice sheet.
The well-calibrated Weichselian scenario can then form the basis for modelling previous ice
sheets, preliminarily their basal conditions, as well as for studying the consequences of extreme
climatic conditions. Such experiments provide bounds for the possible span in conditions that
could conceivably occur.
Simulations on a large scale using the ice sheet model (e.g. northern Europe) can provide input
data for simulations on a smaller scale. This means that local conditions, including both input
data (for example topography, geothermal flow) and output data (for example temperature, basal
meltwater) for the ice sheet model, can be evaluated site-specifically. Data obtained from the
site investigations can thereby simultaneously support the ice sheet project and be interpreted
against the background of the project’s results.
The results of the ice sheet modelling will be stored – together with geological input, calibration
and validation data – in a Gis database. The main analysis work is also done here. Data can be
freely extracted from the Gis database to be used in other projects.
Stress states in the earth’s crust
A project aimed at understanding the mechanisms that lie behind postglacial earthquakes was
commenced in 2003 and is planned to continue for three years. The project will apply finite
element modelling. In an initial phase, basic studies will be conducted with simple earth and
ice models to obtain a good understanding of the physical relationships and the most important
parameters. Since postglacial faults in the Arctic area of Scandinavia are well-known and
investigated, a simulation of the evolution in this area will then be performed. The simulation
will make use of the above-mentioned ice sheet model and also include pore pressure variations,
so the ice sheet’s basal conditions are important here as well. Sensitivity analysis and validation
against available stress and land uplift data will be carried out. As a final step, modelling will be
done for the two candidate sites based on then-available information to indicate whether, and if
so where, postglacial quakes may occur.
Shoreline displacement
In order to be able to describe changes in the shoreline over a glacial cycle and for different
scenarios, a research project is planned where GIA (Global Isostatic Adjustment) modelling
plays a central role. The goal of the project is to identify the factors and processes that influence
the Scandinavian coastline in a 100 to 100,000 year perspective and to develop an isostatic
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