Should this be interpreted to mean that the blast had more force than a 3.3 earthquake?
The seismic wave it way more devastating to the infrastructure. Leading to collapsing buildings, ripped gas pipes etc.
Explosion like this one move most of the energy into the heat and air displacement. The immediate area is shattered but the building outside have only windows smashed.
The explosion look terrifyingly massive but the number of victims seams small in comparison.
In large-scale disasters, a low initial casualty count can be quite deceptive. It often means victims simply cannot be reached, identified, or tallied. In amount of explosive material (not necessarily yield), the Beirut blast compares with the Halifax Explosion of 1917, with 1,950 dead in that incident.
Circumstances, construction, and crowd response (the burning Mont-Blanc had attracted a large shoreside crowd) differ. But beware premature assessment.
Calculations (not maximum estimations) of this explosion put it at < 500 tons.
I'm not sure how AN compares to TNT, but there were reportedly 2700 tons of AN, some fraction of which exploded.
In any case, it looks like the same order of magnitude, or at max one order, rather than 3 or 4.
ETA: the linked USGS actually says 1.1 Kt, but that assumes all the AN participated.
Beirut 2020 involved 2,750 tonnes of ammonium nitrate, same page.
To my mind these are roughly equivilent amounts of raw explosive agent. Some might even argue persuasively that there is slightly more explosive noted in the second.
As I've already conceeded, blast yield TNT estimates may vary, but by whatever specific measure both the Halifax and Beirut explosions were large.
And, to my initial point: damage and casualty estimates may not be instantly available.
Perhaps, but in terms of TNT equivalence picric acid is much more effective at 96% compared to 56% of ammonium nitrate[0] with other estimates being even wider[1] i.e., 1.17x for picric acid to 0.74x for ANFO and 0.42x for ammonium nitrate, and some other figures are placing ammonium nitrate as low as 20% as effective. With the estimates ranging from a low 500 tonnes, ~1.2 kilotonnes for a reasonable estimate up to about a maximum ~2.2 kilotonnes based on 2,750 tonnes of ANFO it's looking like the two explosions aren't that comparable. But I do agree, early estimates of loss of life can be troublesome and both explosions were devastatingly large.
[0] https://www.icheme.org/media/12120/xi-paper-13.pdf
[1] https://en.wikipedia.org/wiki/TNT_equivalent#Relative_effect...
AN tends to deflagrate. It has a positive oxygen balance and therefore is treated as a component in mixtures, which is to say that it is a low-explosive. And just like all other low-explosives, it needs to be confined in order to achieve a proper detonation (i.e. supersonic burn front, which generates a brisant shock front). Alternately, you can supply a shock front from a smaller detonating charge. This hardly means AN is weak, it's very much a workhorse explosive, but some work is required to extract energy from it. This is also why it's safer to work with than most actual high explosives.
Picric acid may not be especially powerful as a military explosive, but its unstable nature has been known for some time. Picric acid achieves a detonation on its own.
What this all means is that if you have an accidental explosion involving picric acid (which is a true high-explosive), you will consume all of it. If you have an accidental explosion involving unmixed AN, it likely won't be fully consumed in a way that contributes to a highly-brisant shock front. If you don't have a brisant shock front, then you more or less have a big fire – scary enough but not an explosion. You get something closer to the fire that destroyed all the crab traps in SF's pier fire, than the Halifax disaster.
Watching video, the possibility that Beirut's grain silo absorbed or reflected much of the blast also occurs. The vapour cloud showed a gap immediately above the structure in initial moments.
I was amazed that the silos were still standing after. Obviously well built - the explosion was right up against it.
Something like a 20-storey Hesco.
Most regular buildings, and quayside warehouses in particular, are surprisingly lightweight and contain comparatively little material, as the remnants of a demolition will frequently attest.
Yes. While "force" might not be the right word, your intuition is correct.
Explosions do not generate transverse side-to-side motions, which are caused by shear forces. For earthquakes, these are known as S-waves, or secondary waves, because they travel slower and arrive at distant locations later. The S-waves usually cause more damage to buildings in an earthquake, because they last longer and induce a shaking or swaying motion.