So. CNN reports that the Secretary-General of the Kataeb political party, name of Nazar Najarian, died from injuries sustained in the explosion. He was in his office.

Google tells me that's almost 900 meters from the blast's epicenter.

1 PSI overpressure shatters glass. 5 PSI overpressure levels wooden-frame residential buildings.

Doesn't look terribly heavy, but it's not wood-frame, either. Hollow block, most likely, esp. given the insulation needs in that part of the world.

The Internet seems to agree that 3.5 PSI is a good medium value for where serious injury can be expected. So let's see what's up. Values under 1kt are simply scaled down from known 1kt explosions, but it's still good for a ballpark estimate.

So, yeah.

Yeah, that's... big.

So! 2,750 tons of ANFO that's been sitting around for years due to legal disputes.

Wikipedia's handy-dandy TNT equivalents page tells me ANFO's relative effectiveness ratio is .74. So that's... about 2,035 tons TNT equivalent.

2 kilotons. https://twitter.com/BalooganCamp/status/1290742004117204992

"...there have been a number of instances when it has spontaneously exploded, at great risk to life and property.... Another is the presence of naturally high temperatures in the ore body..."

7 years in a warehouse.

In Beirut.

https://www.sciencedirect.com/science/article/pii/S2213343717306425

Multiple internet sources state that even 2 PSI over-pressure can shatter hollow cinderblock walls. Shatter. With that in mind...

... this is obviously all the ballparkiest of SWAGS but I'm having a hard time seeing this as anywhere south of 1KT based on what little we know now.

ANFO is typically 94% ammonium nitrate (the oxidizer.) The FO is "fuel oil," 6%. Your average explosive is 25% fuel, 75% oxidizer.

Obviously they don't go mixing the fuel oil into it until they want to use it. But 6% fuel content isn't a whole lot, is it?

Due to this it's unlikely the AN would realize the full explosive power of an actual deliberate ANFO mix; but given how much diesel fuel is typically present in and around a port - to say nothing of other flammable bulk cargo - one might expect a significant fraction.

This is why you see initial explosions precede massive secondaries so often; they tear open containers, disperse fuel into the air, and generally just stir the pot to generate the really bad explosive mix.

We clearly saw that here.

It was VERY fast, though.

My SWAG is definitely on at least 1KT worth of boom because son of a bitch.

In before CNN updates and states that the Secretary-General fell down some stairs from the blast and bumped his head and throws all this off.

If there's anything to those reports of fireworks, that'd definitely explain the fuel source. The pretty pretty colors in those are provided by lots of aluminum foil strips. And they come with their own dispersion charge, even! https://twitter.com/omriceren/status/1290748514184695815