Salt caverns are undergroundcavity formed by drilling and water circular melting salt in underground salt layer.
盐穴就是在地下盐层中通过钻井,利用水循环的方法,将盐层溶解,最终形成一个体积较大的空洞。
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Heavy rains from tropical storm Agatha may also have overloaded underground sewage or drainage pipes, leading to a growing cavity that eventually collapsed, Bonis speculated.
Natural sinkholes generally form when heavy, water-saturated soil causes the roof of an underground limestone cavity to collapse, or when water widens a natural fracture in limestone bedrock.