burst inward; collapse inward as if crushed by external pressure
If a submarine plunges to too great a depth, there is a danger that the water pressure may cause it to implode.
in (into, in, on, upon)#plaudere (to applaud) (Latin)
ex-'out'+plode-'burst'. so im-'in, inwards'+plode-'burst'. so implode means burst inwards