
USGS Data on the Lebanon Blast - browsergap
https://earthquake.usgs.gov/earthquakes/eventpage/us6000b9bx/executive
======
afvictory
Roscosmos has shared before & after satellite imagery for anyone interested:
[https://twitter.com/roscosmos/status/1291023063404994560/pho...](https://twitter.com/roscosmos/status/1291023063404994560/photo/1)

~~~
deadalus
Regarding the satellite image, a few questions :

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?

~~~
azernik
1\. Yes. Not just state actors - Planet Labs
([https://www.planet.com/](https://www.planet.com/)) in San Francisco, for
example, is a commercial satellite company that photographs the whole globe
once per day and sells that imagery online.

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.

~~~
JamisonM

      "Planet Labs ... photographs the whole globe once per day..."
    

This is not an accurate representation of Planet Labs capabilities. I can
attest to this as a Farmer's Edge customer.

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.

~~~
azernik
What is your experience of the frequency of Planet's reimaging? And at what
resolution?

~~~
JamisonM
Somewhere between weekly and every 3 days, occasionally worse. I do not know
the exact resolutions involved but they have "good" and "bad" NVDI images and
the "bad" ones are fairly useless for agricultural applications.

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082349872349872
Somewhat related, the face when you solve for epicentre from seismic station
data and get a location at negative depth:

[https://blogs.ei.columbia.edu/2016/02/04/the-earth-shook-
but...](https://blogs.ei.columbia.edu/2016/02/04/the-earth-shook-but-it-wasnt-
an-earthquake/)

------
eCa
”The reported magnitude is not directly comparable to an earthquake of similar
size because the explosion occurred at the surface where seismic waves are not
as efficiently generated.”

Should this be interpreted to mean that the blast had more force than a 3.3
earthquake?

~~~
me_me_me
I think they mean its different.

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.

~~~
dredmorbius
_...the number of victims seams small ..._

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.

[https://en.wikipedia.org/wiki/Halifax_Explosion](https://en.wikipedia.org/wiki/Halifax_Explosion)

~~~
t-writescode
It does not. The Halifax explosion was calculated at around 2200ktons. Ish.
I’m not looking at numbers right now.

Calculations (not maximum estimations) of this explosion put it at < 500 tons.

~~~
dredmorbius
Halifax involved 2,653 tons of picric acid, a figure not mentioned in the main
Wikipedia article, but noted here:
[https://en.wikipedia.org/wiki/Largest_artificial_non-
nuclear...](https://en.wikipedia.org/wiki/Largest_artificial_non-
nuclear_explosions)

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.

~~~
Aengeuad
>To my mind these are roughly equivilent amounts of raw explosive agent.

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](https://www.icheme.org/media/12120/xi-paper-13.pdf)

[1]
[https://en.wikipedia.org/wiki/TNT_equivalent#Relative_effect...](https://en.wikipedia.org/wiki/TNT_equivalent#Relative_effectiveness_factor)

~~~
dredmorbius
That's specifically not an argument I'm making, but thanks.

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mattlondon
I was looking at the maps for this on the USGS site and thought that the
location of the blast cant be that accurate surely?

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...](https://ichef.bbci.co.uk/live-
experience/cps/624/cpsprodpb/vivo/live/images/2020/8/5/24402a28-1228-4d18-b373-3b3c7e6821d5.png)

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?

~~~
caymanjim
> To remove uncertainties in the location associated with seismic methods, we
> fix the location to the location seen in videos of the blast.

Right at the top of the page.

------
sandworm101
If this involved 2700 tons of ammonium nitrate, does that mean it was the
equivalent to 2700 tons of TNT? A 2.7 kiloton bomb? That would put it at the
smaller end of nuclear weapon yields, but not at the bottom.

~~~
throwaway0a5e
ANFO is only ~3/4 as powerful as TNT per kilogram and this was just amonium
nitrate, not much fuel for it to combust (hence the nice brown smoke).
Additionally, "pile of junk in a warehouse" is second only to "pile of junk
not in a building" when it comes to having the least efficient yield for a
given amount of explosives. Doubtful this is over a kiloton.

It's really hard to make big efficient explosions by accident.

~~~
CLETMP
Furthermore, this wasn't ANFO, just ammonium nitrate. So, no fuel--only
oxidizer. Some analysis has suggested that the efficiency of a detonation here
would only be .15. Furthermore, probably a low-order detonation (only part of
the material detonating). Even actual ANFO typically needs an intermediate
booster explosive to achieve a good high-order detonation. For example,
instead of just having a detonator on its own a blaster might add a PETN
booster charge to make sure the ANFO all detonates. Without that you typically
see pellets of undetonated ANFO scattering around the explosion. Hell, even
with a booster you still tend to see ANFO pellets lying around the blast area.

All that is to say, this was probably closer to 200 tons of TNT, very roughly
speaking.

~~~
sandworm101
Even 200, 0.2kt, is literally on par with the lowest tested nuke.

~~~
penagwin
It’s relatively small compared to similar incidents-

[https://en.m.wikipedia.org/wiki/Largest_artificial_non-
nucle...](https://en.m.wikipedia.org/wiki/Largest_artificial_non-
nuclear_explosions)

~~~
runarberg
According to Wikipedia the Texas City disaster had just over 2000 tonnes of
ammonium nitrate explode (as opposed to 2700 in Beirut) which they claim to be
“one of history's largest non-nuclear explosions”.

Was there some other factor that caused the Texas City to have a bigger blast?

~~~
Jtsummers
If I'm reading it right, the Texas City disaster had 2300 tons on the
Grandcamp, and 961 tons on a nearby ship, the High Flyer. That second ship
exploded later in the day. There was also a chemical plant that was caught in
the blast and a warehouse with fertilizer.

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mytailorisrich
BBC is reporting that people in Eastern Cyprus, ~250km away, felt the blast
and interpreted it as an earthquake. Quite a blast.

~~~
refurb
What the videos capture well is the ground wave.

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.

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m0zg
That's 25 times the yield of the largest conventional munition (Russia's FOAB,
44T yield). The videos look unreal.

------
refurb
I’m assuming that USGS picks up lots of ground movement, for example, large
blasts from mining operations. They must filter those out based on
characteristics? Do companies give advance warning?

Just curious because those instruments must pick up a lot of things that
aren’t earthquakes.

~~~
LinuxBender
USGS eventually learn of rock quarries, mines and other things that cause
regular earth movements and they tune them out of their reporting. A rock
quarry near me used to generated 3.4's a few times a week. I do not know if
there is regular correspondence or schedules relayed however.

~~~
giantrobot
I'm pretty sure blasting requires some permits. In a sane world I'd imagine
blasting permits get automatically funneled into a "booms will be here" list
at least at state levels. But then we don't necessarily live in a same world.

~~~
ajsnigrutin
I'm not from usa, but EU. Here, mining operations, quarries, etc. get "booms
will be here" licences, with limits (when (usually only daytime), where
(quarry/mine limits and how strong the 'booms' are). So for those (rutine,
standard blasts), our enviromental (earthquake) agencies don't get the data
for each blast (they eg. get data, that company XYZ is allowed to do blasts up
to ABC power (KJ or whatever) in location DEF, from 1. jan 2020 to 31. dec
2020 when they have to renew their licence).

Source: friend works as an explosives expert at a quarry

~~~
giantrobot
That level of permitting at least let's environmental agencies get data after
the fact. If they can get the place and time range of blasts they can filter
that out of their measurements. It's probably some poor intern's job. Go
through a stack of permits and mark measurements likely covered by the
permitted blasting.

------
dreamcompiler
So about 1/15 the energy of the Hiroshima nuclear bomb then.

~~~
mrep
And about 1/270 the energy of a single w87 thermonuclear warhead and a single
ICBM can carry up to 10 of those.

~~~
runarberg
That is insane... Makes you wonder why on earth people think its a good idea
to have weapons that can cause 100s of times the damage then this horrible
event.

~~~
ISL
Once one person has one, they can tell everyone else what to do unless other
people have them, too.

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.

~~~
coronadisaster
Why are people so evil...

~~~
ISL
Perhaps some are, but most people are not.

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."

~~~
runarberg
I was always under the impression that the one ring—a weapon so powerful it
will corrupt and destroy everything good in Middle Earth—was an obvious
allegory for the Bomb.

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.

[https://www.un.org/disarmament/wmd/nuclear/tpnw/](https://www.un.org/disarmament/wmd/nuclear/tpnw/)

~~~
browsergap
Agree. But some people will see lack of weapons as weakness to exploit. It's
easier and higher ROI for 1 to arm, while rest disarm, than for all to remain
disarmed, so it will happen. Making the current undesirable state where we
have this fantasy of nuclear slugfest, paradoxically more stable.

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?

