Zone of weakness
A tectonic weak zone is usually a steep structure of the earth's crust that is less stable than the surrounding area.
Typical areas of weakness are:
- the edges of the continental plates (mostly global phenomena); see plate tectonics
- the rifts (large-scale phenomena); see e.g. B. Great African Rift Valley or Upper Rhine Rift
- Geological faults (regional to local); see also mountain formation and sedimentary basins .
The recent - d. H. Weakness zones that are still active today are usually noticeable through movements of the crustal parts, which can be verified geologically, through geophysical phenomena and through geodetic surveying networks. Typical movement rates are a few mm per year, which can occur at sharp fault lines even at a distance of a few meters.
Flat areas of weakness are often the cause of extensive subsidence areas in the earth's crust, which can also be traced back to the history of the earth.