Lateglacial and postglacial faulting in Denmark

The Danish area is divided by the Fennoscandian Border Zone into a north-eastern part, which is generally tectonically stable with low seismicity marginally related to well-known fault zones, and the south-western non-shield part, with close to no seismicity. Stress measurements show that lithospheric plate motion is generally responsible for the modern stress pattern. However, stress changes induced by weight relief from the ice sheets during the Pleistocene appear to have created tectonic instability with maximum intensity at the time of deglaciation. The Danish area is generally covered by thick successions of unconsolidated sediments, and therefore it is often difficult to observe unambiguous examples of glacially induced faults. Nevertheless, a number of examples indicate that faults in major fault zones appear to have experienced short periods of reactivation in Lateglacial and early postglacial times. In this chapter we present an updated map of historic earthquakes in the Danish area, selected examples of Quaternary deformation of the terrain and near-surface sediments, and suggestions for intensified future monitoring, investigations and research.