Thermochemistry plays a huge role in explosions. Thermochemistry can help figure out exactly how much energy is released or absorbed in reactions. All chemical reactions should be exothermic reactions releasing more energy than absorbed. Other wise the explosion is useless, and this would be endothermic reactions. Enthalpy is usually used to find the exact output of energy in a reaction. Enthalpy is the energy of products subtracted by the energy of reactants.
Being able to know how much energy is released in reactions is crucial. For example 47% of all explosions in the United States is used for coal mining. Scientist must know the exact output of explosions so they create enough vibrations to break rock, but not so much as too destroy everything else. That is why thermochemistry is crucial in explosions. It tells you how much energy is released in a precise form.