Map of Geohazards in Lower Saxony — Mass Movements (WMS Service)

The State Office for Mining Energy and Geology (LBEG) publishes in scale 1: 50 000 and 1: 25,000 Geohazards in Lower Saxony. These hazard information maps present the natural hazards of subrosion and mass movement by individual objects (earthfall, mass movement) or the demarcation of endangered areas (earth-risk area, salt stock elevation). Mass movements are geomorphological processes in which rock or loose stone, under the influence of gravity, move downhill in periods from seconds to years. Natural causes such as an unfavorable inclination of geological layers or weathering of rock sections favor the formation of mass movements. Ultimately, triggers of a mass movement can be both natural (downfall, etc.) as well as anthropogenic (construction measures, traffic, etc.) influences. Mass movements cause serious damage to buildings, roads, railways or waterways due to spilling with rock or loose rocks and deep terrain breaks. Sliding, fall and flow processes are distinguished as superordinate movement processes of mass movements. The motion mechanisms tilting and drifting are no longer differentiated and are assigned to one of the higher-level processes. • Sliding processes are downhill, sliding movements of fixed and/or loose rocks on discrete sliding surfaces. During movement, the slip compound on the sliding surface largely maintains contact with the solid surface. Slides are classified by the shape of the sliding surface, so that it is necessary to distinguish between translation and rotation slides or a combined sliding surface shape. • In a fall process such as a rockfall or a rock fall, the falling masses temporarily lose contact with the solid ground. Boulders or rock masses fall, jump or roll downhill following gravity. Fall processes are classified according to the volume of the collapsed rock material. • Flowing processes such as earth/shoe/block currents, murmuring and creep movements of all kinds have no defined sliding surfaces. In contrast to the slipping process, the water content of the flowing masses is usually significantly increased. The movement is comparable to a highly viscous liquid. Flow processes are classified according to their speed of movement. The basis of the map of geohazards in Lower Saxony — mass movements — with a representation of the individual objects — is an event cadastre based on information from topographic, geological and engineering geological maps, reports and literature. In one case, a high-resolution, digital terrain model from laser scan images (LIDAR) could be evaluated. The mass movements hazard statement map is geared to the needs of spatial planning, not parcel-sharp and does not replace object-related geotechnical examination. The map representation documents the current state of knowledge in the LBEG, but cannot guarantee the completeness of the phenomena. It serves ministries, specialised authorities, district and local governments as well as business enterprises and citizens as the first basis for risk assessment with the aim of preventing or minimising damage caused by predictive planning. Areas adjacent directly to the designated areas may also be affected. The intensity and probability of a possible event cannot be derived from the map. Local circumstances (e.g. protective measures, renovations, topographical features) must be taken into account in further investigations.