Breaking news

Theory seems to be a 180,000 (pound or gallon, reports vary) propane tank blew. The explosion was felt 10 or 15 miles away.

If it was propane the most likely cause was a propane leek that filled the facility with gas before it got ignited. Propane tanks rarely burst because of their multiple pressure relief valves, however reporters, and most laymen don't know this, and believe the tank exploded.

That, or a small fire at the tank caused it to burst (BLEV).

Dave

A small leak explosion could potentially set off the tank via propagation wave explosion ie a high order type. Looks to be what might have happened given the damage.

ED

I like how they emergency professionals are telling commuters to avoid the area.

People have jobs!!

You do whatever it takes to not get fired!

If you have to drive through a danger zone to make it to work then oh well!!

Executives don't care, why should you?

Again although it is theoretically possible to make a propane tank explode standard design practice on large tanks is to assume a large fire is built around the tank when it is full, and one of the three or more pressure relive valves is defective. Under these conditions the other relive valves must be able to vent the gas into the air fast enough to prevent over pressurizing the tank.

I do not know the work schedules at this facility, but if the workers were in the process of entering the facility to start work at 9:00 AM one of them could have done something that ignited gas that had leaked into part of the facility during the night.

Just saw a photos of the tanks and they looked intact, but what a disasters . Looks like a war zone.

ED