I'm seeing Ammonium Nitrate being tossed around as a potential cause. May have also been a place that stored fireworks from things i've read.

(EDIT)
Replaced original video (https://youtu.be/wqKn_3iJOP4) to the one currently embedded. It has all the videos in the previous embed plus many more.
(EDIT)
All the below videos are now included In the current embedded video.

Here is a list of different angles someone posted on reddit
Angle #1 https://streamable.com/xmmoa7
Angle #3 https://streamable.com/zbjj5f
Angle #4 https://streamable.com/saoafz
Angle #6 https://streamable.com/lmivb2
Angle #7 https://streamable.com/mcy82f
Angle #8 (in above video) https://streamable.com/zg9oal
Angle #9 (in above video) https://streamable.com/zykkj6
Aftermath https://streamable.com/4ga1vb

It's Tetsuo

Thought you said Tiësto. My bad.

https://www.youtube.com/watch?v=kzUqhw_yymM

Easy mistake, he is the bomb!

*wtf *news *fire *death

Adding video to channels (Death, Fire, News, Wtf) - requested by ant.

I saw a video on Twitter of the carnage pretty close to ground zero. The ground was covered with that gray dust like the kind that coated NYC after 9/11; a total moonscape. The person taking the video showed that there were bodies and parts of bodies everywhere.

Also, 2.7kt is pretty damned impressive, considering Ft Man was like 12kt.

*fear

Adding video to channels (Fear) - requested by Zawash.

Latest reports indicated those confiscated Ammonium Nitrate been sitting there for 6 years. WTF?

Apparently a lot of it didn't combust and was expelled by the blast. I saw an estimate of 1kt equivalent which is still massive.

I believe it did all go up, the explosion was about 1.1kt (TNT equivalent) because Ammonium Nitrate is about 0.4 times the explosive power of TNT.

The large, windowless square structure is grain storage. It blocked some of the blast but represents a large fraction of Lebanon's grain supply.

More details from https://www.moonofalabama.org/2020/08/beirut-blast-wrap-up.html#more

-------------------------%<--------------------------------%<------------------------------ RFERL spoke with the captain of the ship that had unintentionally brought the ammonium nitrate to Lebanon. He confirms the ship's arrest. It also reports the cause of the incident:

Lebanon's LBCI-TV reported on August 5 that, according to preliminary information, the fire that set off the explosion was started accidentally by welders who were closing off a gap that allowed unauthorized entry into the warehouse.

LBCI said sparks from a welder's torch are thought to have ignited fireworks stored in a warehouse, which in turn detonated the nearby cargo of ammonium nitrate that had been unloaded from the MV Rhosus years earlier.

Independent experts say orange clouds that followed the massive blast on August 4 were likely from toxic nitrogen dioxide gas that is released after an explosion involving nitrates.

There is a short video of firefighters at the initial fire. Reportedly none survived when the fireworks fire set off the ammonium nitrate. Another video shows the initial fire caused by welding. It burns a while and then sets off fireworks in a first explosion. This takes the roof off the warehouse. A few minutes later the fireworks cause the huge explosion of the ammonium nitrate.

Reuters provides another detail:

The source said a fire had started at port warehouse 9 on Tuesday and spread to warehouse 12, where the ammonium nitrate was stored.

That the ammonium nitrate was stored for seven years was not the responsibility of the port management but was caused by some judicial quarrel:

The head of Beirut port and the head of customs both said on Wednesday that several letters were sent to the judiciary asking for the dangerous material be removed, but no action was taken.

Port General Manager Hassan Koraytem told OTV the material had been put in a warehouse on a court order, adding that they knew then the material was dangerous but “not to this degree”.

“We requested that it be re-exported but that did not happen. We leave it to the experts and those concerned to determine why,” Badri Daher, director general of Lebanese Customs, told broadcaster LBCI.

Two documents seen by Reuters showed Lebanese Customs had asked the judiciary in 2016 and 2017 to request that the “concerned maritime agency” re-export or approve the sale of the ammonium nitrate, which had been removed from cargo vessel Rhosus and deposited in warehouse 12, to ensure port safety.

The colour of the plume apparently indicates a lot of unexploded nitrates. Ammonium Nitrate needs to be mixed with other things for an efficient reaction. Once the explosion started the reaction couldn't continue efficiently and the excess was expelled into the plume.

Ammonimum nitrate does require a sensitizer in order to be explosive, however this stuff was intended for blasting, so it presumably already had something mixed in with it. The other requirement is a low explosive detonator, eg blasting caps. In this case it was probably a random accident, so not as efficient as a deliberate blasting setup.

Various bomb experts have mentioned that the plume would be black if it was ANFO or similar meaning it wasn't mixed.

It was Ammonium Nitrate and the rumor is--Hezbollah wanted access to the 2500 tons to use...in bombs/IEDs, etc.