measured in hundreds of newtons per sq m (thousandths of a kilogram-force per sq cm). At great distances the blast wave is a sound wave(or an elastic wave in a solid medium).
Sound waves in the atmosphere (or elastic waves in the earth’s crust) caused by explosions of sufficiently great energy can be recorded by special devices (microbiological, seismographs, and so on) at great distances. For example, for explosions with energies on the order of 1013 joules (several thousand tons of TNT), waves are recorded at distances of several thousand kilometers; for explosive energies of 1016 joules (several million tons of TNT), waves are recorded at almost any point on earth. At such great distances a blast wave is a long sequence of extremely low-frequency oscillations of atmospheric pressure (or ground tremors in the case of underground explosions). (See Figure 2.)