On 06/08/2020 09:58, Andy Burns wrote:
Martin Brown wrote:

Previous such events have been recorded as an initial primary
explosion followed a fraction of a second later by a massive secondary.

This would also be consistent with people close to the blast saying
they lost their hearing and then later saw the glass go flying in shards.

One of the newspaper correspondents was initially convinced there had
been one blast *in* the city centre (it knocked him off his feet inside
his flat) followed by a separate blast at the docks.

The crater is immediately adjacent to those grain silos, which could
have acted as a blast wall, reflecting a second pressure wave after the
initial bang from the 'fertiliser'.

Andrew wrote:

The crater is immediately adjacent to those grain silos which could
have acted as a blast wall
Pretty good before after shots

https://i.guim.co.uk/img/media/fabdf9932a25b67c2213d456132d42f9f7745ab5/0_0_2560_1536/master/2560.jpg?width=1900&quality=45&auto=format&fit=max &dpr=2&s=bbcfc824a7eca967881bcc824a02c12a

warehouse buildings are likely to be pretty lightweight (steel frame
with corrugated roof/sides?) but still ...

Or go to The Guardian for mouse-slidy overlaid versions

On 06/08/2020 14:51, Andrew wrote:
On 06/08/2020 09:58, Andy Burns wrote:
Martin Brown wrote:

Previous such events have been recorded as an initial primary
explosion followed a fraction of a second later by a massive secondary.

This would also be consistent with people close to the blast saying
they lost their hearing and then later saw the glass go flying in
shards.

One of the newspaper correspondents was initially convinced there had
been one blast *in* the city centre (it knocked him off his feet
inside his flat) followed by a separate blast at the docks.

The crater is immediately adjacent to those grain silos, which could
have acted as a blast wall, reflecting a second pressure wave after the
initial bang from the 'fertiliser'.


Different mediums create different waves in different moments for the
same force.

I find pre explosion evidence interesting. One of the videos shows
clearly, a reaction taking place before a visual explosion of the NA pile.

For Brian, camera looks onto pile of NA in the far distance and below
the camera. Though not obvious, the view is over the edge of a smooth
rounded ridge that drops below camera view revealing the NA pile.

The ridge takes up full width of the view.

The last 3 screen captures show no change in the time stamp of Youtube.
It happens within the second I begin the captures.

Pic 01 shows the state during countdown.
Pic 02 shows a white dot appear on the ridge a fair way left of camera.
Pic 03 Shows this white dot disperse very quickly into what seemed like
a low dust cloud that clings close to the ridge. It dispersed to the
right of where the dot was.
Pic 04 Shows the pile explode, spraying outward and up, a red orange
cone. No obvious shock wave. However, the 'cloud' on the ridge appears
to grow outward along the ridge. It increases in density and further
along the ridge as the explosion grows. This might be a lensing effect
disturbed by a pre explosive force.


Explosion
01 - Pre Explosion Environment
http://prnt.sc/tv54vv
02 - Pre Explosion with white dot on hill ridge
http://prnt.sc/tv55f2
03 - Pre Explosion. White dot dispersion
http://prnt.sc/tv55rw
04 - Explosion
http://prnt.sc/tv568f