All 5 dead in deep-sea sub implosion

Hidden killer: Incredible force at depth of 3,800 meters

A "catastrophic implosion", such as that believed to have destroyed the Titan submersible, would have happened with incredible force and speed given the crushing water pressure on the floor of the ocean.

The remains of the Titanic rest on the seabed in the North Atlantic at a depth of some 3,800 meters.

At sea level, atmospheric pressure is 14.7 pounds per square inch, or psi, which equals 101.3 kilopascal.

Water pressure at the depth where the ocean liner lies is equivalent to around 400 atmospheres, nearly 6,000 psi.

As a comparison, the bite of a large great white shark exerts a force of nearly 4,000 psi, according to Scientific American.

In an implosion caused by a defect in the hull or for some other reason, the submersible would collapse in on itself in milliseconds, crushed by the immense water pressure.

Roderick Smith, an engineering professor at Imperial College, London, said the accident was likely due to a "failure of the pressure hull", but debris will need to be recovered to carry out a full investigation.

And even then, it may be difficult to pinpoint the cause. "The violence of the implosion means that it may be very difficult to determine the sequence of events," Smith said.

AGENCIES VIA XINHUA