USGS Data on the Lebanon Blast
earthquake.usgs.gov
earthquake.usgs.gov
1) Can nation-states spy like this on every location on the planet?
2) Can you view the live feed of any location and follow vehicles(for example)?
3) Is there anything a country can do to prevent other's from spying on your country from satellites?
2) Well, I can't, but the capability exists.
3) Dig.
following vehicles is near impossible commercially (resolutions are too low)
2. Live feed is a bit tricky, and that's where governments have an advantage - they own their own satellites, and can task them to follow a specific target. But you have to know where the target is at the start of the window, they don't have real-time video of the whole planet, and unless you've got a very big fleet you won't always have a satellite overhead when you want to look at your target.
3. Keeping track of the times of satellite passes overhead, hiding stuff underground, putting your aircraft in covered hangars and only moving them at night, putting a roof on your military docks, using upwards-facing camouflage, etc. Same methods that have been used for a hundred years to hide from air surveillance.
I would really not be surprised to see the NRO go the Planet Labs / Starlink route at some point in the future and put 20 satellites in a dozen orbital planes to provide coverage everywhere at less than 60 degrees latitude 24/7/365. Sure, maybe you need the big KH-11s for the extremely high resolution shots - but 3m resolution isn't exactly trash either.
Starlink
"Planet Labs ... photographs the whole globe once per day..."
In the theoretical world where every inch of the earth was photographed every day things like losing MH-17 likely wouldn't have happened.
ETA: Planet claims "entire landmass" every day but I find that claim extremely suspect, but it does not even claim the entire globe.
I think you mean MH370 instead of MH-17.
So you can’t like fly a 3D orbit, fly at same altitude but different angular velocity, or change course without expelling significant amounts of mass. You play by those rules.
All the diff is to be atrributed to this blast? Am I missing anything obvious here?
The structure to the far left on parents before picture is apparently removed before the explosion.
[ps. The frequency shift is definitely reflecting vehicle direction - right side of highway is BGR, the other side is RGB. Delays in the sequence of 3 filtered captures?]
[1] https://directory.eoportal.org/documents/163813/5615117/SkyS...
https://blogs.ei.columbia.edu/2016/02/04/the-earth-shook-but...
Should this be interpreted to mean that the blast had more force than a 3.3 earthquake?
Yes. While "force" might not be the right word, your intuition is correct.
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.
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.
Image from the BBC showing the location of the blast on a satellite image:
https://ichef.bbci.co.uk/live-experience/cps/624/cpsprodpb/v...
It looks like the crater (crater! wow this was huge) was almost exactly where USGS plotted it to be, like down to a couple of meters.
Are the earthquake sensors that are in use really this so specifically accurate?
Right at the top of the page.
It's really hard to make big efficient explosions by accident.
All that is to say, this was probably closer to 200 tons of TNT, very roughly speaking.
https://en.m.wikipedia.org/wiki/Largest_artificial_non-nucle...
Was there some other factor that caused the Texas City to have a bigger blast?
Ammonium ion is the fuel when pure ammonium nitrate explodes.
Adding fuel oil increases the power for a couple reasons - 1) fuel oil adds additional fuel 2) ammonium nitrate absorbs water from the atmosphere and makes it much less sensitive. The fuel oil “waterproofs” the ammonium nitrate.
No, because ammonium nitrate isn't equivalent to TNT. Various sources give the REF of Ammonium Nitrate as 0.42, so at most it should, by itself, be equivalent to 1134 tons of TNT, but the actual explosion could be less because of inefficient ignition, or more if it set off something else that added to the explosion.
https://news.ycombinator.com/item?id=24053732
Nuclear weapons span a huge range of yields. The W54 yield was as low as 10 tons, about as energetic as a daisy cutter conventional bomb.
News reports state the explosion was caused by 2750 tons of ammonium nitrate which is roughly equivalent to 1100 tons of TNT.
You see the blast, then the building shakes within a second, then the atmospheric shockwave arrives a few seconds later.
Gives you a sense of the power - to violently shake the ground from over 1km away.
Just curious because those instruments must pick up a lot of things that aren’t earthquakes.
Source: friend works as an explosives expert at a quarry
Before 9/11, this was literally a cash and carry business in many States. You could back up a truck and fill it with explosives as long as you had a placard for your truck and a non-sparking liner. It simply isn't practical to track usage in many cases, even today.
I didn't need any permit. I needed: 1) to prove that I was not a felon, so that it was legal for me to have access to the explosives, 2) permission from the landowner, and 3) to inform the fire department in advance (that was exactly the "booms will be here" list).
Note that this was pre-9/11. Current rules are likely more restrictive.
https://www.atf.gov/explosives/binary-explosives
> Mixing binary components together constitutes manufacturing explosives. Persons manufacturing explosives for their own personal, non-business use only (e.g., personal target practice) are not required to have a Federal explosives license or permit.
You might need to find a more remote location than a suburban backyard, however, as local authorities may have some objections too.
However, tectonic earthquakes are rapid sliding movements of the crust along a fault that is a quasi-planar surface. This leads to patterns in the seismic waves, where half of them, two quadrants, show a compressional push away from the source and the other two quadrants have the first motion as tensile, or a pull towards the source. By looking at the geographic locations of the seismic instruments and seeing which show a pull and which show a push, seismologists fit planes separating the quadrants which correspond to the azimuth and inclination of the fault that caused the earthquake.
(edit: deleted ascii art which did not render correctly.
Interestingly, the orientation of the fault and the quadrants of push and pull reflect the directions of the stress field in the crust caused by plate tectonic motions, as well as secondary sources of stress such as gravitational loading of the crust from high topography, or the expansion and contraction of magma chambers under volcanoes. In the 60s through the 80s, geophysicists used this information to put together the first models of the rates and directions of different tectonic plates, but we now mostly use GPS for this.
Until we find a way to alter that incentive structure, mutually-assured destruction remains one of our best-available options for tenuous stability and peace.
On the latter subject, I offer the advice of Gandalf:
Gandalf: "You cannot offer me this Ring!"
Frodo: "I'm giving it to you!"
Gandalf: "Don't tempt me Frodo! I dare not take it. Not even to keep it safe. Understand Frodo, I would use this Ring from a desire to do good. But through me, it would wield a power too great and terrible to imagine."
The point of the fellowship was not to study the ring, make their own, and keep the peace in Middle Earth with a mutual assured destruction. Instead they had the fellowship take the ring back to Mordor where it would be destroyed.
Tolken does not seem to share your belief that: “mutually-assured destruction remains one of our best-available options for tenuous stability and peace”.
EDIT: And neither does the United Nations. I encourage you to read the Treaty on the prohibition of nuclear weapons (and subsequently ask your government to sign it if they haven’t already) and see why the presence of nuclear weapons among our nation states is a terrifying and dangerous endeavor.
But yeah, in a sense it's like we're storing AN in a warehouse beside a city. Seemingly stable, but bad if not. Unless we're not storing AN, but just sawdust. But who knows really?
an even more stable situation would be to have every country convinced they have a mutually assured destruction but then for there to be some higher power that can prevent that. so we don't start a war because we believe mad is true but even if we do there's a fallback. but who knows?