Sorry to piss on the chips but...
Glaciologist Dr Richard Hodgkins - who has studied the Svalbard glacier - said the area was a sensitive location and an early indicator of climatic changes.
So, not long then, in fact pretty instantaneous, rather like a chunk of ice falling on the deck when you're a few feet from an iceberg
Steward: "Would sir like ice with that?" ...... C-R-A-S-H
Passenger: "Ferrrrrrrkin' 'ell! ... that was quick"