Last two days of the Dyatlov group: 3. Blast wave – a possible timeline

[Arjan]

Part three of a possible timeline of the last two days of the Dyatlov group is drafted, assuming: 
1.   The map below reflects the situation.
2.   No outsiders have entered the map until the arrival of the first search party.
3.   The members of the Dyatlov group have acted as ‘may be expected’.
4.   No internal violence within the group.
5.   No manipulation with the photos from the search parties and from the mortuary.
6.   The information in the autopsy reports reflects the professional findings of the coroner.



1 February 1959

Around 15:30 pm
The Dyatlov group had been abruptly forced to end the usual preparations for the night, because:
•   Around 1 second, Lyudmila, Semyon and Thibo had been ‘enveloped’ by a blast wave, that had caused a fatal chest injury for Lyudmila, a life-threatening chest injury for Semyon and a life-threatening head injury for Thibo.
•   Around one second later, the tent and the 6/7 group members at the tent site had been ‘enveloped’ for 1 second by a similar – considerably diminished – blast wave.

Remark: This kind of blast waves travel with a speed well above 500 m/s (1800 km/h).

The timeline for this kind of ‘moderate’ blast wave is:

Time zero (Around 15:30 pm on Feb 1st for the Dyatlov group):
Being hit by the shock front of the blast wave in its simplest form described as ‘Friedlander waveform’, see as example the graph below.



Few milliseconds later
Being fully enveloped by the overpressure/compression of the blast wave: the overpressure will very quickly diminish.
During these few milliseconds:
•   Small particles will be accelerated to high speeds.
•   The shock front is too brief to provide a considerable accelerate of ‘massive’ objects (like stones and human bodies): the displacement of massive objects is very limited.
•   Solid parts of the body (filled with water) can withstand this kind of moderate pressure waves rather well.
•   ‘Closed’ cavities – ribcages – will be uniformly compressed by this ‘moderate’ high pressure, causing so-called butterfly fractures in the ribs.





•   This kind of butterfly fracture is hard to imitate (in ribcages) by applying other kinds of trauma. See further: ‘Rib butterfly fractures as a possible indicator of blast trauma’, a study by Angi M Christensen and Victoria A Smith (summary available via: https://pubmed.ncbi.nlm.nih.gov/23126284/ ).
•   Eardrums will often rupture.
•   Blood vessels in legs and arms may get coagulated and/or remain filled with blood. This may be an explanation for the photos of the underarms of Yuri Dor in the mortuary, and for the statement in Zinaida’s autopsy report: ‘There is a very pronounced venous system on the legs and feet’ while nothing of a ‘pronounced venous system on the legs’ is visible on an earlier photo of Zinaida in swimming suit.
•   Yuri Dor. may have developed a so-called blast lung: he had been found with ‘around the right cheek, the soft tissue is covered with a layer of foamy grey fluid. Grey fluid traces are also visible around the opening of the mouth’. Cough (productive with frothy sputum) may be one of the symptoms of a blast lung. See:   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4919801/
•   The shape of the tent will get compressed.
•   The (top layer of) snow will be compressed and start to melt.

Around 100 milliseconds later
The pressure is normal again for a few milliseconds.

Between 100 and 1000 milliseconds later
The overpressure is followed by decompression (under pressure)
During these 900 milliseconds:
•   Lyudmila, Semyon and Thibo had lost consciousness and they had started to collaps.
•   The ribcages of Lyudmila, Semyon and Thibo had expanded (uniformly) beyond the normal volume. The photo of Lyudmila in the mortuary shows no outside damage to her ribcage and hardly any deformation of her ribcage. Very probably Semyon’s ribcage had been indented/deformed – as visible on the photo in the mortuary – later: e.g.: during a fall or when he had been transported/placed by other group members to the den or he had been placed near/in the creek by other group members.
•   Small particles had injured the eyes of Lyudmila and Semyon.
•   This decompression had probably caused the condensation of water vapour in the air: this may result in a so-called ‘white-out’ until the mist will evaporate again in the dry cold air.
•   The tent had been ‘inflated’ by the under pressure.
•   Depending on the level of pressure followed by under pressure, hollow parts of bamboo ski poles may crack as visible on a photo made by the first seach party.





See also internet: ‘Exploding Bamboo: The Origins of the Firecracker’. 

Remark: One cannot hide for this kind of blast wave behind a wall/object of in a ditch/trench/cave.

One or two seconds later
The tent had started to take – more or less – its normal shape and it had collapsed on the 6/7/ group members who had been inside the tent at that time.
The tent cloth had fallen on the group members in the tent.
One or two group members (Yudi Dor and Yuri Kri?) had cut themselves in panic out of the tent downhill (see: case file 34).
Outside the tent the group members had been engulfed by:
•   heavy winds and
•   so-called ‘white-out’.

Several minutes later
The swirling heavy winds had settled and the ‘white-out’ had lifted.
The (top layer of) snow will start to turn into ice.

After recovery from the panic
One opening of the tent had been erected on one ski pole: this part of the tent had been intended as emergency bivouac to initiate the recovery from the panic.

The photo – made by the first search party – shows that part of the tent had been erected again on one ski pole.
This half-erected tent had provided an excellent emergency bivouac for 2/3 group members – one wounded, the other to guard and take care – during the cold night, that had been fatal for the other members in the den and near the cedar. 



Explanation of the effect of a pressure wave within the ravine

The image below shows schematically the argumentation why Lyudmila and Semyon both had been standing at the bottom of the ravine and why Thibo had been standing on the upper edge of the ravine.



The profile of this kind of ravine acts as a hollow mirror for the reflection of the blast wave on the ground.

In case around 40 % of the energy is reflected on flat ground, the profile of the ravine had increased/converted the pressure of the blast wave with around 100 % on the ribcage of Lyudmila/Semyon compared to the pressure on the ribcage of Thibo. This may well explain why Lyudmila and Semyon had been found with a broken ribcage as a primary injury caused by this kind of blast wave and Thibo not (on the edge of the ravine, the reflection had decreased/diverted the pressure considerably).

Very probably Thibo would have started to suffer from a so-called ‘blast lung injury’ in case he might have lived half a day longer.

Lyudmila and Semyon had been found with injuries to both eyes. These injuries may well have been initiated as secondary injury due to the reflection of the blast wave on the ground causing small particles from the ground hitting (with high speed and penetrating) the retina of their eyes.

The image below illustrates how Thibo may have been injured to his head as secondary injury due to the blast wave (in case he had been standing on the upper edge of the ravine): he had lost consciousness during the blast wave and he had started fallen sideways from the edge of the ravine: around 5 meters lower, the side of his head had hit a round stone at the bottom of the ravine with a speed around 10 m/s (or 36 km/u).



Basic general information about this kind of blast wave
1.   McNab, Chris & Keeter, Hunter, Tools of Violence. Wellingborough: Osprey, 2008, Chapter 2 ‘Perfect Destruction – Explosives’
2.   Wikipedia: https://en.wikipedia.org/wiki/Blast_wave , paragraphs: ‘Characteristics and properties’, ‘Mach stem formation’, ‘Damage’
3.   Christensen, Angi M & Smith Victoria A, ‘Rib butterfly fractures as a possible indicator of blast trauma’. See: https://pubmed.ncbi.nlm.nih.gov/23126284/

[GlennM]

Would such a blast affect the trees in the area? Would it affect the snow on the trees?

[Arjan]

Thank you for your question.

In case of an huge blast wave with extreme high pressure: trees, humans, water will fully evaporate.
A high pressure wave will cause broken skulls, broken eyeballs and cause heart failure. Use as keywords for the search: 'blast wave injury'   

Let's assume it is a moderate blast wave.

Water can withstand high pressure without much reduction of volume.
Air will be considerably compressed by high pressure.
Testing a pressure vessels to the limit by applying pressure is always done with fluids, and never with air.

For the snow on the ground and on the trees, this pressure wave will compress the snow (and raise the temperature of the snow) during 100 milliseconds.
The snow on the trees will melt and partly evaporate.
The snow on the ground will be compressed, melt and partly evaporate.

During the decompression stage (around a second) water vaper in the air will condensate to fog.
The top layer will cool down again: the water will slowly turn in ice.
If my memory serves me well, one member of the search party had said during in interview that the area of the stonerange between the tent and the ravine had been covered with an ice toplayer.

Trees and most parts of the human body can withstand this moderate blast wave rather well, but the hollow parts of trees and the human body are vulnerable; especially the mid ear and the lungs.
Rib cages will uniformly by compressed during 100 milliseconds and again inflated beyond its normal size during the decompression stage lasting 900 millisecond.

In trees and in bamboo, the hollow parts are vulnerable for weakening by compression to be damaged (split, explode) during the decompression.
Buildings are weakened by the uniform compression and will be damaged during the decompression stage.
 
Very probably many people will loose consciousness during at least a few seconds due to a sensory overload, these people collaps and fall in line with the progress of the blast wave.

The shock wave lasts too briefly to cause much displacement to heavy/massive.

P.S.: if all will go as scheduled, the last two part of this possible timeline will be posted, covering the fatal night for 6 group members and the fatal next day for Zinaida and Rustem (according to this timeline his watch had stopped on February 2nd at 20:00 pm).   

[GlennM]

In WWII, German shelling in Verdun could be heard in Paris, a distance of 163 miles. Vishay is 40 miles from Dyatlov Pass.

[Arjan]

Thank you for this reply.

In case a blast wave had been the onset for the fatal outcome of the tour, the group members had not heart the sound of the blast wave.

It is highly likely that the pressure front of the blast wave had travelled supersonic with a speed well above the sound barriere.
This includes that the group members had been enveloped by the pressure wave and their eardrums had been ruptured before they had any change to hear the blast pressure wave.
The group members at the tent site had probably lost consciousness for a brief time, before they had been able to be conscious of the sound.

It may well be assumed that in Vizhai the blast wave had been audible with a rumbling/snappy sound like an airplane going through the sound barrier.
Halfway during the cold war in Europe it had been common to hear exercising military fighterplanes going through the sound barrier.
Maybe this kind of sound had not be uncommon in Vizhai and surroundings. 

[GlennM]

No one asked the Mansi, nor the people in Vishay . Opportunity lost.