"Implosion is a process in which objects are destroyed by collapsing (or being squeezed in) on themselves. The opposite of explosion, implosion concentrates matter and energy. True implosion usually involves a difference between internal (lower) and external (higher) pressure, or inward and outward forces, that is so large that the structure collapses inward into itself. An example of implosion is a submarine being crushed from the outside by the hydrostatic pressure of the surrounding water. Also, it is helpful to note that due to the processes that cause an implosion, the object reacts from the inside out." From Wikipedia: Implosion (mechanical process).
To be continued.