What is Implosion?
Implosion is a process of destruction by collapsing inwards the object itself.
Where explosion expands, implosion contracts.
In the case of the Titan Submergible. the Implosion was caused due to very high hydrostatic pressure of the surrounding water, which happen within a fraction of a millisecond, as shown in the animation.
At the depth the Titanic rests, there is around 5600 pounds per square inch of pressure.
That's almost 400 times the pressure we experience on the surface.
As the submersible is deep in the ocean, it experiences the force on its surface due to the water pressure.
When this force becomes larger than the force hull can withstand, the vessel implodes violently.
But why did this Implosion happen to the Titan Submersible.
(Existing technology is based on) Current hull materials used are steel, titanium, and aluminium. These are what kept other submarines from being Crushed.
But the Titan has had an experimental design. It used mostly carbon fibres, which have the advantage of being lighter than titanium or steel.
The properties of carbon fibres for deep sea applications are, however, not that well understood. It can crack and break suddenly.