The lowering of the Earth's crust due to loss of support from beneath the ground is known as which of the following?

Land subsidence refers to the gradual sinking or settling of the Earth's surface due to the removal of subsurface support, typically as a result of factors such as the extraction of groundwater, oil, or minerals. When these materials are extracted, the weight that was previously held by them is no longer supported, leading to voids that can cause the overlying ground to compress and subsist.

This process can happen over varying time scales, from years to decades, and may result in significant changes to the landscape, including the collapse of structures and the alteration of water drainage patterns. It is a critical factor to consider in urban planning and environmental management, especially in areas prone to excessive resource extraction, as it poses risks to infrastructure and can lead to ecological disturbances.

The other options mentioned do not accurately describe this phenomenon. Crust disintegration may imply a breaking down of rock materials rather than sinking. Earth fall could suggest sudden rockfalls rather than the gradual process of subsidence. Sudden valley is not a recognized geological term that relates to the sinking of land. Thus, land subsidence is the most appropriate term in this context.