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If the sand is water-saturated, as I imagine it is in many places in India, it can start to behave like a liquid. Liquefaction has a couple of consequences for shaking : some of the potentially damaging shaking gets absorbed, which can be a good thing, but if the ground beneath a structure starts behaving like a liquid, the structure no longer has a solid foundation. It's like it's sitting on quicksand. Even a well-built building can just tip over.