We ask three questions to researchers at the Department of Civil, Environmental and Natural Resources Engineering at Luleå University of Technology on causes and effects from a quake of this size.
What caused the earthquake?
– Earthquakes in Sweden often depends on the elevation of the land where the bedrock is slowly pushed upward after the last ice age, which depressed the bedrock. Crustal outer part consists of solving tectonic plates that change of heating and cooling the Earth's crust. This causes the continental plates to move and deform. A pressure can be built up between the two plates which then generates an earthquake when the voltage gets too high, and parts of the bedrock breaks, says Olof Martinsson, researcher in Ore geology at The Division of Geosciences and Environmental Engineering.
How safe is our infrastructure when earthquakes of this magnitude occur?
– In the design of our infrastructure we are using a factors of safety against unknown and known actions. This factor of safety covers also rare loads like those from earthquakes of lower magnitude. If displacements occur they are very small for dams and other engineered slopes. They are in the order of millimeters for the types of earthquakes to be expected and will not endanger any dam safety, says Jan Laue, professor in Soil Mechanics at The Division of Mining and Geotechnical Engineering.
There is a risk of earthquakes of the magnitude we have seen in Haiti and China, even in Sweden?
– You can not say that there will never occur a major earthquake in Sweden, but the research and measurements show that our part of the world has a very stable bedrock. The earth is divided into larger and smaller so-called tectonic plates and it is between these plates the high risk areas for earthquakes are located. Scandinavia is very stable, seen from a geological perspective, says Pär Weihed, Professor of Ore Geology.
Below a link to a European-seismic map where the most vulnerable areas are shown in red. It is clear that Northern Sweden is not a high risk area for major earthquakes: