The geological phenomenon of subsidence is the process by which a part of the Earth's surface lowers or sinks compared to the surrounding areas. This can happen for various reasons and can affect areas of varying sizes, from a few square meters to entire regions.
One of the most common causes of subsidence is the extraction of water, oil, or natural gas from the pores of the underlying rocks. When these fluids are removed, the ground loses some of the support it had and can collapse or compact, leading to a lowering of the surface.
Some types of soil, especially those rich in clay, can naturally compact over time under their own weight, especially if they are water-saturated. This compaction process can lead to the subsidence of the surface above them.
The phenomenon can also be caused by movements of the tectonic plates beneath the Earth's surface. For example, if one plate moves downward relative to another, this can cause a gradual lowering of the surface.
One of the most famous cities affected by subsidence is Venice, which has experienced a progressive lowering of the ground and the foundations of buildings due to excessive extraction of groundwater and the natural compaction of the sandy and clayey soils on which it is built.
The effects of subsidence can cause the lowering of the ground, which can lead to cracks and damage to buildings, roads, bridges, and other infrastructure, and alter the natural water flow, causing drainage problems and increasing the risk of flooding.
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