Which class/division explosions generally cause severe structural damage to adjacent objects?

Class 1.1 explosives are characterized by their capability to produce a mass explosion, which is defined as the detonation of a substantial quantity of explosive material. This type of explosion can cause severe structural damage to nearby objects because the energy released is vast and affects a significant area. Such explosions typically involve large quantities of high explosives and pose a serious risk not only to proximity personnel and equipment but also to the surrounding environment due to the blast wave, heat, and fragmentation.

In contrast, Class 1.2 and 1.3 explosives do not have the same potential for mass explosion; they may produce non-mass explosions or a series of smaller explosions. Class 1.4 explosives present a lower hazard and are designed in such a way that they do not pose a significant risk of mass detonation, primarily affecting only the container or the immediate area without causing extensive collateral damage.

Therefore, the severity of damage associated with Class 1.1 explosives, due to their mass explosion potential, is why they are identified in this context as causing acute structural damage to adjacent objects.