Highlighting or the corresponding reduction in the mean Geosciences a vertical movement in connection with endogenous forces of the earth - for example in the formation of mountains - and goes to underground movements ( mantle , volcanic ) or wedge back -Effects as well as isostatic , the force balance of the land masses over the liquid mantle of the earth. Raising and lowering effects are part of bradyseism , the slow movement of the earth.
The Geodynamics has various causes for raising or corresponding reductions:
- within the framework of plate tectonics , through thrust or under thrust ( subduction )
- due to transverse forces in connection with folding during the formation of fold mountains
- Postglacial land uplift as a late consequence of the Holocene glaciation
- Uplifts above filling magma chambers , also corresponding subsidence after their emptying after an eruption
- Spontaneous increases and decreases after earthquakes
- large-scale uplifts over plumes in the interior of the earth
- local movements caused by swellable rocks in the subsoil such as swelling clays or anhydrites during the transformation into gypsum
- local or regional movements through open-cast lignite or mining , for example hard coal mining .
The growth of the Alps , as well as other young fold mountains of the Alpine formation phase, for example, is made up of the effects of the post-glacial uplift, the underlying folding and the counteracting erosion . Overall, there is an average uplift of one to two centimeters per century with local fluctuations. The slopes of the Alps are therefore permanently on the verge of an unstable steepness. In connection with the rise of the permafrost limit, this effect is responsible for landslides in the Alps and is important for the identification of danger zones in the danger mapping for settlement areas. In the most active phases of mountain formation, the uplift is probably in the range of several mm / year.
The spontaneous uplifts and subsidence after severe earthquakes lead to large-scale faults in the rock layers. These reach by far the highest speeds, several meters in a few seconds. These earth movements show particularly devastating effects in deep sea areas, where they transfer large amounts of energy due to the displacement of water during large-scale uplifts and are the cause of tsunamis . The December 26, 2004 event was caused by a floe tipping over with elevations of up to a dozen meters.
In the Phlegraean Fields on Vesuvius, the coastline has sunk 8 m in the last 2000 years, numerous Roman palaces and villas , as well as ancient port facilities, are here below today's sea level . In addition to well-known, traditional examples, the extent of uplift movements in historical times was only recognized in the last few decades, and has made underwater archeology an important field of research. Her more significant successes include the discovery of ancient Herakleion (Egypt) including the presumed foundations of the Pharos of Alexandria in 2000/2001, which today are almost ten meters below sea level. These enormous subsidence are only partly a result of the global warming since then and the increase in volume of the water, but partly a compensatory movement between the Alpine elevation and the - subsequently explained - African plum, and many more discoveries in the eastern Mediterranean are to be hoped for.
The rise / fall of the sea level , in which the regional elevation of the sea floor relative to normal water level plays a role, plays a decisive role in both the emergence and disappearance of land bridges in both animal migration and plant spread .
In Fennoscandia be heave 1-2 cm / yr, similar orders of magnitude and also be measured elsewhere. This is hardly noticeable to humans, but the higher geodesy has to track its reference model, the geoid , to the changing geoid undulations ( dynamic topography )
- Dieter Richter: General Geology. 4th edition, Walter de Gruyter, Berlin - New York 1992.
- Karl Vogt: Textbook of Geology and Petrefactenkunde. Volume 2, second edition, printed and published by Friedrich Vieweg and Son, Braunschweig 1854.