Contemporary technogenic movements of the earth's crust

Technogenic movements, caused by Man's activities, are subdivided on the basis of their causative factors, which are: changes in hydrodynamic and hydrostatic conditions at depth during the process of withdrawal and injection of fluids, the effect of static pressure during mining operations, the redistribution of static loads on the surface, and dynamic interactions during explosions. During the removal of fluids and solid rocks from below, downwarping of near-surface portions of the sedimentary shell and crust takes place, which cannot for the most part be regarded as tectonic.

The creation of additional loads during the construction of large cities and the building of large reservoirs cause downwarping of the crust on the order of a few tens of centimeters with a velocity on the order of 1 cm/yr, and also earthquakes of magnitude up to 5-6. The patterns of manifestation of this type of movement are considered on the basis of three major dams: North America (Lake Mead), Africa (Kariba), and India (Koyna).

During underground nuclear explosions in Nevada, substantial faults were engendered over an extent of hundreds of meters up to kilometers for a distance of up to 6 km from the point of detonation.

Technogenic movements may embrace not only the sedimentary shell, but also the consolidated crust. In their characteristics, and also the areas and depths of the sectors of the crust involved, the technogenic movements in a number of cases cannot be distinguished from present-day natural tectonic movements, in every case local. —Authors.