This is somewhat drifting off topic as other Henry points out, but brief on
methodology:
http://www.nuclearweaponarchive.org/Nwfaq/Nfaq5.html
Sec 5.6.2 on blast damage and injuries.
The first good video of the aftermath was from inside a building quickly
geolocated as highrise on Berberi St between that and the ring road Charles
Helou, 630 meters from the centerpoint of the blast in the warehouse
(Fabian Hinz @ MIIS geolocated it while I was trying to). We had a good up
close look at the damage inside the building, with the frame standing ok
but windows blasted out on all sides and window frames bent inwards,
concrete block side walls cracked and broken inwards, etc.
Merely breaking glass is a minimum of around 1 PSI blast overpressure. 5
PSI and you expect buildings like that and other standard construction to
start collapsing; 10 PSI and everything along that road would have
collapsed. So we had limiting cases of around 2 PSI to 5 PSI with reason
to think in the middle (2-3 PSI) as we had no evidence at the time of any
buildings south of harles Helou collapsed (have since).
The blast equations in NWFAQ are approximate but accurate enough. R_blast
= y^0.33 x constant_bl at pressure point. R_blast in kilometers, y in
kilotons TNT equivalent, constant_bl see below (and please don't scream
about dimensional analysis...)
For 3 PSI for example the constant is 1.0, for 1 PSI it's 2.2, for 5 PSI
it's 0.7 . Unofficially for 2 PSI it's 1.5
Working backwards from 630 meters and those bounding and likely pressure
levels, we could find Y that would give that pressure at that distance.
That ended up with extreme estimates between 70 tons ( 2 PSI) 240 tons (3
PSI) and 665 tons (5 PSI). Again, tons energy TNT equivalent not raw tons
of material.
Note that this was before we had any data on material or amount, though the
red cloud suggested AN decomposition.
The rule of thumb for AN not mixed with fuels is 10% of weight equivalent,
but it varies 3% to 30% (median range 10-15%). Using the smoke color for
material and 10% equivalence I was getting something like 2400 tons of AN
early on and thinking that was ridiculous, who'd store 2,400 tons of AN
that close to inhabited parts of a city...
An alternate method starts with the methods in Paul Cooper's "Explosives
Engineering" air blast effects chapter rather than the NW FAQ methods but
they're essentially equivalent for these ranges and energies.
We're currently gathering sources to try to measure local (100-500 meter)
shockwave intensity based on the degree of damage to the thin metal panel
thick metal frame warehouses in the port. We have a variety of damage to
those ranging from even the frame collapsed to frame intact but all the
panels blasted off to panels bowed inwards but still attached to panels
damaged but not all collapsed inwards. Also looking for more details of
what collapsed where in the city proper.
Last time something like this came up it was because of the fuel and
warheads explosion in a bunker under a mountain in Yemen's capital
Sa'naa during Saudi bombing, which came out around a kiloton or two
equivalent. Jeffrey Lewis and I originally met over both trying to
independently analyze the damage when Iran's solid fuel rocket program base
Bidganneh detonated in 2011 in a weapon handling accident.
-george
On Wed, Aug 5, 2020 at 5:51 PM Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx>
wrote:
On 8/5/2020 5:35 PM, George Herbert wrote:
On Aug 5, 2020, at 12:48 PM, Peter Fairbrother <peter@xxxxxxxxxx>
<peter@xxxxxxxxxx> wrote:
Last point, some observation-based calculations suggest that the explosion
had a power of about 200 tons TNT (not my calculations, I know I often get
numbers wrong here but these are from the pros). The grain silo
absorbed/deflected much of that, protecting the city quite a bit.
Hello. I’m right here ...
-George
Presumably Peter was avoiding outing you as a courtesy. But since you do
seem to want credit, got any more details on that 200-ton yield estimate
you can share?
Henry
