Reflection of the Blast Wave at a Surface

When the incident blast wave from an explosion in air (Fig. 9.3) strikes a more dense medium, such as the Earth s surface, either land or water, it is reflected. 

When such reflection occurs, an object precisely at the surface will experience a pressure increase, since the reflected wave is formed instantaneously the value of the overpressure thus experienced at the surface is generally considered to be entirely a reflected pressure. In the region near ground zero, this total reflected overpressure will be more than twice the value of the peak overpressure of incident blast wave. 

There are two important destructive aspects of the blast wave involved 

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