Detonative Phase Transformations and Earthquakes

IN detonation, the energy liberated supports a shock front the impact of which on as yet unreacted material induces further energy release progressively. Elementary hydrodynamic theory suggests that it should be possible for a wide variety of physico-chemical reactions to be propagated in this way, at their characteristic detonation rates. But in practice detonation has been observed only for comparatively very few systems. The main reason for the (fortunate) rarity of detonations in physico-chemical reactions is that unless its liberation is very rapid, most of the energy of reaction can be dissipated sideways, instead of contributing to the hydrodynamic propagation of the shock front, the impact of which has in turn to trigger transformation in unreacted material ahead of it. Normally as a result of lateral energy losses, only very intense reactions can establish a detonation front with sufficient stability to be identifiable as such in the laboratory, or on the ordinary technological scale.