In laboratory and open ocean combustion tests, there have been no documented cases of LNG BLEVEs. It is a theory that has never been capable of being produced and has been tested several times.
LNG SAFETY MYTHS and LEGENDS
http://www.netl.doe.gov/publications/proceedings/02/ngt/Quillen.pdf
Here's a youtube video putting out an LNG fire:
“LNG put to the test”
http://www.youtube.com/watch?v=C75-J09Ld8A&feature=channel_page
I've been an LNG proponent for some time. We are in the process of getting an LNG terminal here in Oregon.
(Northern Star, Bradwood Landing site)
It's still not a done deal, but FERC has passed it. The local loonies are fighting it tooth and nail, however.
The latest hurdle is that the terminal is in a salmon estuary.