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If one plans to build a survival structure below ground then certain pressure can be expected when liquefaction takes place during the near 
continuous shaking at the time of a pole shift.
Different kinds of sand have different densities; however 2.3 g/ml is a typical value. Water has a density of 1 g/ml. The following chart can be used 
to predict the amount of pressure on a container or survival quarters at a given depth below the surface of the ground. 

The following can be used to convert pounds per square foot (PSF) to pounds per square inch (PSI). 

Offered by Mike.