Consistency of postglacial geodynamics for the Kattegat region, southern Scandinavia, based on seismological, geological and geodetic data

摘要

Te earthquake map of Denmark is constantly being improved. Together with data from western Sweden and southern Norway it shows more and more convincingly a gradual,scattered earthquake activity across the Kattegat region fromlow activity in the Precambrian basement of Scandinavia tolack of earthquakes in south-western Denmark and northern Germany. Te activity is only partly connected withmapped geological features. Te three most recently feltearthquakes in Denmark augment and support this patternwith two or three activity concentrations in the seas aroundDenmark (Fig. 1). T e smoothness and irregularities of thispicture must in some way be related to the geological structure as well as to the geodynamic pattern of postglacial uplifmapped from geology and geodesy. Since the dominant stressfeld, from the lithospheric plate motion is smooth (Gregersen & Voss 2010), a natural question is whether the picture of postglacial uplif, seen from the geological and geodeticperspective shows local irregularities? Te broad-scale uplifpattern in Denmark since the last Ice Age has been knownsince the review published by Mertz (1924). All later papershave referred to this general pattern of uplif towards thenorth-east and subsidence towards the south-west with reference to the present sea level. Te present paper relates theregional seismological pattern to the smooth and consistentpatterns in postglacial geology and geodesy, as well as to theexisting local investigations on geodynamics. Interpretationsof the measured uplif of shorelines on L?s?, in the middleof the Kattegat (Fig. 2), have given rise to opposing views onregularity versus irregularity between the present authorsand Hansen et al. (2012). Te measurements show that theelevation of the oldest postglacial shorelines on L?s? ft inthe regional pattern with regard to elevation, but not withregard to time. In this paper we propose that the time di?erence is only apparent.