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What natural hazard occurs in areas underlain by limestone?
Sinkholes
Sinkholes are common in areas underlain by limestone.
Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground.
Why does ground subsidence occur?
Subsidence caused by withdrawal of ground water, oil, and gas has been observed and studied for more than 100 years (Poland and Davis, 1969; Strehle, 1989). Subsidence often occurs due to man’s need for fresh water, oil, and gas to satisfy domestic, industrial, and agricultural demands.
What steps can be taken to mitigate subsidence hazard?
Adjusting the level of groundwater exploitation and rationally controlling the mining time can effectively control land subsidence. For coastal cities, preventive measures should also be taken to reinforce the seawall, and build dikes to prevent flooding and seawater intrusion.
Where does land subsidence occur?
Subsidence is a problem everywhere In many areas of the arid Southwest, and in more humid areas underlain by soluble rocks such as limestone, gypsum, or salt, land subsidence is an often-overlooked environmental consequence of our land- and water-use practices.
What is a sinkhole caused by?
Sinkholes are formed when the land surface above collapses or sinks into the cavities or when surface material is carried downward into the voids. Drought, along with resulting high groundwater withdrawals, can make conditions favorable for sinkholes to form.
What are some examples of areas that have been affected by subsidence?
Land subsidence caused by man-induced depressuring of underground reservoirs has occurred in at least nine urban areas in the United States. Significant efforts to control it have been made in three areas: Long Beach, California; Houston-Galveston, Texas; and Santa Clara Valley, California.