Engineering Geological Map of Lower Saxony 1 : 50 000 - Earth-hazardous areas
Description
Subrosion is the subterranean leaching and transport of mostly easily soluble rock. Subrodable are chemical sediments, such as the easily soluble chlorides rock salt and potash salt, sulphate rocks such as gypsum and anhydrite (sulfate karst) and also the heavier soluble carbonate rocks, e.g. limestone (carbonate karst). Most of the damage in Lower Saxony is due to the leaching of sulphate rocks.
In the case of subrosion, a distinction must be made between regular and irregular leaching. Regular leaching takes place on the surface of the subrodable rock and leads to wide-span, usually small subsidences of the terrain. Irregular leaching focuses on a small-scale, narrowly confined area and can lead to the formation of caves, slofts or clots. It progresses in solid rock, especially along crevices or joints in the rock. Therefore, loosened mountain areas in tectonic fault zones are usually areas of intensive subrosion.
If the limiting load-bearing capacity of the mountain over a cavity is exceeded, this cavity can collapse and break through to the earth's surface (earthfall). The layer thickness of the soluble rock and thus the possible size of a cavity are decisive for the size of the burglary on the surface of the terrain. About 50 percent of the earth falls in Lower Saxony have a diameter of up to two meters and at about 40 percent the diameter is between two and five meters. Although these diameters seem quite small, the impact on structures can be very large.
The map IEG50 shows areas in which there is an area-wide danger from earthfalls.
The information presented in the map does not replace a soil survey in accordance with DIN EN 1997-2 (DIN 4020).
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https://nibis.lbeg.de/net3/public/ogc.ashx?NodeId=195&Service=WMS&Request=GetCapabilities& |
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