Surveys on environmental tectonics

Abstract

Until now, research on neotectonics and related seismicity has mostly focused on active plate boundaries characterized by generally high earthquake activity. Current seismic hazard estimates for intraplate areas are commonly based on probabilistic analyses of historical and instrumental earthquake data. The accuracy of these hazard estimates is limited by the nature of the data (e.g. ambiguous historical sources) and by the restriction of available earthquake catalogues to time scales of only few hundred years, which are geologically insignificant and not suitable to describe the tectonic processes causing earthquakes. This is especially relevant to intraplate regions where faults show slow slip rates resulting in long average recurrence times for large earthquakes (10 3–10 6 yr). The Alpine orogen and intraplate sedimentary basins and rifts of its northern foreland are associated with a much higher level of neotectonic activity than hitherto assumed. Seismicity and stress indicator data, combined with geodetic and geomorphologic observations, demonstrate that the northern Alpine foreland is being actively deformed. This has major implications for the assessment of their natural hazards and environmental degradation. The NW European lithosphere has undergone a polyphase evolution with an intensive interplay of upper mantle thermal perturbations and stress-induced intraplate deformation. A number of recent findings point to an important role of lithospheric folding in thermally weakened lithosphere of the northwestern European foreland. The EU funded interdisciplinary ENvironmental TECtonics research network (ENTEC) addresses relationships between deeper lithospheric processes, neotectonics and surface processes in the northern Alpine foreland. Its objectives are to quantify the effects of ongoing Alpine collision on NW European Foreland intraplate deformation and its impact on surface geomorphology and natural hazards. Three natural laboratories have been selected: (1) the Lower Rhine Graben (LRG), (2) the Upper Rhine Graben (URG), and (3) the Vienna Basin (VB). These three areas record the manifestation of neotectonics within the Alpine orogen (VB), at its front (URG) and in the far field area (LRG).