US warns residents before testing 'massive' bomb

The US air force is due to test a 21,000lb bomb and is warning Florida residents that they can expect to hear it for miles around.

Officials at Eglin air force base in Florida say the volume of the 'massive ordnance air burst' bomb or MOAB, will depend on the wind, and some people may not hear it at all.

But people living in communities around the western half of Eglin have been told to be ready for an explosion that sounds like thunder or a slamming door.

Officials say the test will be conducted only under the best weather conditions for minimising the sound, and inside a buffer zone to keep a shock wave and debris from the blast inside the base's boundaries.

The MOAB is similar to, but 40% heavier than, the BLU-82 - billed as the world's most powerful non-nuclear bomb and known to send up a mushroom cloud similar to a nuclear weapon.