Dyatlov Pass
Avalanche Model and Remaining Questions
▲ Cover of the incident – Unfolding the records
In 1959, nine experienced mountaineers died in the Ural Mountains. Torn tents and scattered bodies have given rise to numerous hypotheses, and recent studies have suggested the physical possibility of a sheet avalanche.
The Dyatlov Pass is more likely to be explained as a chain of accidents in an extreme environment rather than as a supernatural phenomenon. However, possibility and complete reconstruction are different.
Prologue: The night that broke records
When I laid out the case data on my desk, the first thing I noticed was not the correct answer but an imbalance. Some scenes were overly clear, and some time periods were completely blank. People try to explain the entire incident by focusing on one clear scene, but I instead marked the blank section first. Mysteries can arise because there are many clues, but they can also arise because the distance between clues is too great.
The expedition set up their tents on the slopes of Mount Holatshahl. The search team identified a tent with signs of being cut inside, and bodies found in different streets.
I did not view this incident as confirming an already known conclusion. The records were arranged chronologically, the movement paths of objects were drawn separately, and sightings and interpretations were indicated in different colors. The most popular explanations were then deliberately reviewed last. Because when you first read a famous hypothesis, all the clues seem to exist for that hypothesis.
▲ On-site reconstruction — last confirmed movement route
Case Files: What I Could Believe
| number | confirmed record | current reliability |
|---|---|---|
| 1 | The tent was set up by digging out the snow on the slope, and the environment allowed for strong winds and snow redistribution. | high |
| 2 | Some of the crew members were lightly dressed and showed signs of moving in the direction of the forest. | high |
| 3 | Causes of death included hypothermia and severe trauma. | middle |
| 4 | A 2021 academic study modeled the possibility of delayed occurrence of small sheet avalanches. | middle |
The exact timing of the trigger, how any injuries occurred, the order in which the crew moved, and details of the rescue attempt remain.
The sentence ‘It is not explained’ is not the same as the sentence ‘It is supernatural’ or ‘Someone intended it’. I didn't use the blank space as evidence.
▲ Timeline – Flow before and after the event
Reconstructing the Scene: Finally, a Certain Point
I changed the location where the incident took place to the actual route rather than the stage in my head. We divided the starting point, final confirmation point, and discovery location and calculated the time needed in between. In the process, several later dramatic depictions were omitted. Instead, the recorded sounds, weather, means of transportation, and locations of objects came to the fore. The novelistic atmosphere arose from the very texture of the facts. There was no need to add unidentified secret passageways or nameless accomplices.
When reconstructing the last scene, I did not determine the character's feelings. The same behavior can be caused by fear, planning, mistake, or fatigue. So, I wrote down the actions first and left the emotions to the extent possible. Thanks to this principle, events became less flashy but more concrete.
Clue 1. The tent was set up by digging out the snow on a slope, and it was an environment where strong winds and snow redistribution were possible.
I placed this sentence in the middle of the case record and checked the tense first. It was differentiated from who observed it and when, and whether it was written down on the spot or added from memory later. The older the clues to an unsolved case, the more seamless the story becomes. However, what is needed in an investigation is not smoothness but provenance. The moment I discerned whether this clue was a direct observation, a trace left by an object, or someone's interpretation, the outline of the incident changed.
If we leave out this clue, a one-way conclusion seems very plausible. But I immediately tried the next record: “Some of the crew were lightly dressed and showed signs of moving in the direction of the forest.” If the two do not naturally coexist in the same explanation, the explanation is still just a story. In particular, a hypothesis that does not pass the question “How much did tent location and snow redistribution increase the actual risk?” ignores the rest of the record instead of explaining one clue.
So I created three spaces in my case notes. The first is a confirmed fact, the second is an inference that goes one step further from the facts, and the third is a possibility that cannot be selected without additional evidence. This clue is a mixture of parts that are close to the first space and parts that stay in the second space. I didn't erase that boundary. Leaving boundaries is the only way to modify your reasoning later when new records emerge.
▲ Key Clue 1 — Traces left by records
Clue 2. Some of the crew members were lightly dressed and showed signs of moving in the direction of the forest.
I placed this sentence in the middle of the case record and checked the tense first. It was differentiated from who observed it and when, and whether it was written down on the spot or added from memory later. The older the clues to an unsolved case, the more seamless the story becomes. However, what is needed in an investigation is not smoothness but provenance. The moment I discerned whether this clue was a direct observation, a trace left by an object, or someone's interpretation, the outline of the incident changed.
If we leave out this clue, a one-way conclusion seems very plausible. But I immediately tried the next record: “Causes of death included hypothermia and severe trauma.” If the two do not naturally coexist in the same explanation, the explanation is still just a story. In particular, a hypothesis that does not pass the question “Should eye pressure and ravine falls be considered together for injuries?” ignores the rest of the record instead of explaining one clue.
So I created three spaces in my case notes. The first is a confirmed fact, the second is an inference that goes one step further from the facts, and the third is a possibility that cannot be selected without additional evidence. This clue is a mixture of parts that are close to the first space and parts that stay in the second space. I didn't erase that boundary. Leaving boundaries is the only way to modify your reasoning later when new records emerge.
▲ Key Clue 2 — Pieces that do not fit together
Clue 3. Causes of death included hypothermia and strong trauma.
I placed this sentence in the middle of the case record and checked the tense first. It was differentiated from who observed it and when, and whether it was written down on the spot or added from memory later. The older the clues to an unsolved case, the more seamless the story becomes. However, what is needed in an investigation is not smoothness but provenance. The moment I discerned whether this clue was a direct observation, a trace left by an object, or someone's interpretation, the outline of the incident changed.
If we leave out this clue, a one-way conclusion seems very plausible. But I immediately tackled the next record: “2021 Academic Study Models Small Plate Avalanches May Delayed Occurrence.” If the two do not naturally coexist in the same explanation, the explanation is still just a story. In particular, a hypothesis that does not pass the question “What is the core reason for not returning to the tent after an emergency departure?” ends up ignoring the rest of the record instead of explaining one clue.
So I created three spaces in my case notes. The first is a confirmed fact, the second is an inference that goes one step further from the facts, and the third is a possibility that cannot be selected without additional evidence. This clue is a mixture of parts that are close to the first space and parts that stay in the second space. I didn't erase that boundary. Leaving boundaries is the only way to modify your reasoning later when new records emerge.
▲ Key Clue 3 — Evidence that shakes the hypothesis
Clue 4. A 2021 academic study modeled the possibility of delayed occurrence of small sheet avalanches.
I placed this sentence in the middle of the case record and checked the tense first. It was differentiated from who observed it and when, and whether it was written down on the spot or added from memory later. The older the clues to an unsolved case, the more seamless the story becomes. However, what is needed in an investigation is not smoothness but provenance. The moment I discerned whether this clue was a direct observation, a trace left by an object, or someone's interpretation, the outline of the incident changed.
If we leave out this clue, a one-way conclusion seems very plausible. However, I immediately tried to compare it to the next record, “The tent was installed by digging out the snow on the slope, and the environment allowed for strong winds and snow redistribution.” If the two do not naturally coexist in the same explanation, the explanation is still just a story. In particular, a hypothesis that does not pass the question “How much did tent location and snow redistribution increase the actual risk?” ignores the rest of the record instead of explaining one clue.
So I created three spaces in my case notes. The first is a confirmed fact, the second is an inference that goes one step further from the facts, and the third is a possibility that cannot be selected without additional evidence. This clue is a mixture of parts that are close to the first space and parts that stay in the second space. I didn't erase that boundary. Leaving boundaries is the only way to modify your reasoning later when new records emerge.
put three hypotheses on the same scale
Hypotheses were not evaluated in fancy sentences. We wrote down the number of explanatory clues, the number of new assumptions required, and the degree to which they can withstand contrary evidence. Even if one clue is completely explained, if the remaining three clues have to be discarded, it is not a good hypothesis.
Hypothesis A. Explanation that they urgently left the tent because they felt the risk of a plate avalanche.
The advantage of this explanation is that it accepts the proviso that “the tent was installed by digging out the snow on a slope and was in an environment where strong winds and snow redistribution were possible” with relatively few assumptions. I first assumed that this hypothesis was true and re-traced the event from beginning to end. Each sentence linked where and what the character saw, what judgment he made, and then moved to the next location. There was always a hidden assumption at the point where the connection was lost.
The biggest weakness is that it does not sufficiently explain that “the causes of death included hypothermia and strong trauma.” If you keep adding exceptions to your hypothesis, you can explain anything, but such an explanation predicts nothing. I lowered the score of the hypothesis the moment there were more than two exceptions. Conversely, scores were increased only when two independent clues pointed in the same direction.
In the end, this hypothesis cannot be completely discarded, but it cannot be taken as a conclusion either. If you read the incident like a novel, the blank spaces will be filled in naturally. If you read it like an investigation record, the blank spaces remain. I chose the latter. Even if the blank space left is inconvenient, that inconvenience protects the scope of what the evidence can say.
Hypothesis B. Explanation that there was a chain reaction of errors in judgment due to strong winds, hypothermia, and darkness.
The advantage of this explanation is that it makes relatively few assumptions about the clue “Some of the members were lightly dressed and showed signs of moving in the direction of the forest.” I first assumed that this hypothesis was true and re-traced the event from beginning to end. Each sentence linked where and what the character saw, what judgment he made, and then moved to the next location. There was always a hidden assumption at the point where the connection was lost.
The biggest weakness is that it does not sufficiently explain “A 2021 academic study modeled the possibility of delayed occurrence of small sheet avalanches.” If you keep adding exceptions to your hypothesis, you can explain anything, but such an explanation predicts nothing. I lowered the score of the hypothesis the moment there were more than two exceptions. Conversely, scores were increased only when two independent clues pointed in the same direction.
In the end, this hypothesis cannot be completely discarded, but it cannot be taken as a conclusion either. If you read the incident like a novel, the blank spaces will be filled in naturally. If you read it like an investigation record, the blank spaces remain. I chose the latter. Even if the blank space left is inconvenient, that inconvenience protects the scope of what the evidence can say.
Hypothesis C. Explanation that there were external factors such as military experiments
The advantage of this explanation is that it makes relatively few assumptions: “Causes of death included hypothermia and severe trauma.” I first assumed that this hypothesis was true and re-traced the event from beginning to end. Each sentence linked where and what the character saw, what judgment he made, and then moved to the next location. There was always a hidden assumption at the point where the connection was lost.
The biggest weakness is that it does not sufficiently explain that “the tent was installed by digging out snow on a slope, and it was an environment where strong winds and redistribution of snow were possible.” If you keep adding exceptions to your hypothesis, you can explain anything, but such an explanation predicts nothing. I lowered the score of the hypothesis the moment there were more than two exceptions. Conversely, scores were increased only when two independent clues pointed in the same direction.
In the end, this hypothesis cannot be completely discarded, but it cannot be taken as a conclusion either. If you read the incident like a novel, the blank spaces will be filled in naturally. If you read it like an investigation record, the blank spaces remain. I chose the latter. Even if the blank space left is inconvenient, that inconvenience protects the scope of what the evidence can say.
▲ Comparison of hypotheses – explanatory power and gaps
Conclusions I threw away
When I began my investigation, I too was drawn to the most popular explanation. It summed up events in one sentence and gave intention to every object. But when the data was collated, the explanation required a new coincidence for every blank space. I erased that conclusion and started again. Good reasoning is less about adding things and more about removing unnecessary assumptions.
The avalanche model is not a definitive determination of the entire event, but proof that it is physically possible. The external intervention hypothesis lacks concrete physical evidence, and natural disaster explanations do not automatically resolve all the details.
In particular, details repeated in later testimonies and on the Internet were separated from the original records. Just because the same sentence appears in multiple places does not mean there are multiple independent sources. First, we checked the possibility that a single incorrect sentence was duplicated. After going through this process, the size of the case decreased, but the weight of the remaining clues actually increased.
▲ Counterevidence check — the conclusion I discarded
Final Reason: What I arrived at
The Dyatlov Pass is more likely to be explained as a chain of accidents in an extreme environment rather than as a supernatural phenomenon. However, possibility and complete reconstruction are different.
This conclusion is not a completely definitive ruling. This is a direction that requires the fewest assumptions and simultaneously explains the most clues within the currently available records. It may be revised as new physical evidence emerges. However, it is also clear that the conclusion may change depending on what comes out. Reliable original records, verifiable forensic data, and independent evidence directly linking objects and people are needed.
I do not write that the case is closed. Instead, write down how far you can close it. That boundary is the result of this investigation. The fun of mystery is not that anything is possible. The goal is to find out which of the possible explanations can be discarded.
▲ Final judgment – explanation that requires the fewest assumptions
Additional Investigation Records 1. Redraw the timeline
At dawn, I opened the case sheet again. This time, the conclusion was obscured, leaving only the following record: “The tent was installed by digging out the snow on the slope, and it was an environment where strong winds and snow redistribution were possible.” Even events you thought you already knew reveal a completely different picture if you erase the conclusion. I lined up the locations and times and wrote down the minimum travel time. The gaps between records were not filled by imagination but were marked with empty squares. As the square grew, the reliability of the hypothesis explaining that section decreased.
Above that, I put the hypothesis, “The explanation is that they urgently left the tent because they felt the risk of a plate avalanche.” At first everything seemed to fall into place. But when we asked the question, “How much did tent location and snow redistribution actually increase the risk?” a weak point in the explanation was revealed. Hypotheses must withstand questioning. If you keep bringing in new characters or coincidences to avoid questions, from that moment on, it becomes creation rather than reasoning. I used my creative sense only for the mood of the sentence and did not place it in the place of facts.
The results I got from this section are neither a definitive name for the culprit nor a complete decipherment. Instead, it became clear which explanations required fewer assumptions and which ones flipped when new discoveries were made. Even if the case cannot be closed, it is possible to narrow the scope of the investigation. This record is intended to leave behind that narrowed boundary.
Additional investigation record 2. The missing link
At dawn, I opened the case sheet again. This time, the conclusion was obscured, leaving only the record, “Some of the members were wearing light clothing and there were traces of moving in the direction of the forest.” Even events you thought you already knew reveal a completely different picture if you erase the conclusion. I lined up the locations and times and wrote down the minimum travel time. The gaps between records were not filled by imagination but were marked with empty squares. As the square grew, the reliability of the hypothesis explaining that section decreased.
Above that, I put up the hypothesis, “The explanation is that there was a chain reaction of strong winds, hypothermia, and errors in judgment in the dark.” At first everything seemed to fall into place. However, when we asked the question, “Should eye pressure and canyon falls be considered together for injuries?” a weak part of the explanation was revealed. Hypotheses must withstand questioning. If you keep bringing in new characters or coincidences to avoid questions, from that moment on, it becomes creation rather than reasoning. I used my creative sense only for the mood of the sentence and did not place it in the place of facts.
The results I got from this section are neither a definitive name for the culprit nor a complete decipherment. Instead, it became clear which explanations required fewer assumptions and which ones flipped when new discoveries were made. Even if the case cannot be closed, it is possible to narrow the scope of the investigation. This record is intended to leave behind that narrowed boundary.
Additional investigation records 3. Witness distance
At dawn, I opened the case sheet again. This time, the conclusion was obscured, leaving only the record, “The cause of death included hypothermia and strong trauma.” Even events you thought you already knew reveal a completely different picture if you erase the conclusion. I lined up the locations and times and wrote down the minimum travel time. The gaps between records were not filled by imagination but were marked with empty squares. As the square grew, the reliability of the hypothesis explaining that section decreased.
Above that, I put the hypothesis that “there was an explanation that there were external factors such as military experiments.” At first everything seemed to fall into place. However, when we asked the question, “What was the key reason why we could not return to the tent after the emergency departure?”, a weak part of the explanation was revealed. Hypotheses must withstand questioning. If you keep bringing in new characters or coincidences to avoid questions, from that moment on, it becomes creation rather than reasoning. I used my creative sense only for the mood of the sentence and did not place it in the place of facts.
The results I got from this section are neither a definitive name for the culprit nor a complete decipherment. Instead, it became clear which explanations required fewer assumptions and which ones flipped when new discoveries were made. Even if the case cannot be closed, it is possible to narrow the scope of the investigation. This record is intended to leave behind that narrowed boundary.
Additional investigation record 4. The path the object took
At dawn, I opened the case sheet again. This time, the conclusion was obscured and only recorded, “Academic research in 2021 showed as a model that small plate-shaped avalanches can occur with a delay.” Even events you thought you already knew reveal a completely different picture if you erase the conclusion. I lined up the locations and times and wrote down the minimum travel time. The gaps between records were not filled by imagination but were marked with empty squares. As the square grew, the reliability of the hypothesis explaining that section decreased.
Above that, I put the hypothesis, “The explanation is that they urgently left the tent because they felt the risk of a plate avalanche.” At first everything seemed to fall into place. But when we asked the question, “How much did tent location and snow redistribution actually increase the risk?” a weak point in the explanation was revealed. Hypotheses must withstand questioning. If you keep bringing in new characters or coincidences to avoid questions, from that moment on, it becomes creation rather than reasoning. I used my creative sense only for the mood of the sentence and did not place it in the place of facts.
The results I got from this section are neither a definitive name for the culprit nor a complete decipherment. Instead, it became clear which explanations required fewer assumptions and which ones flipped when new discoveries were made. Even if the case cannot be closed, it is possible to narrow the scope of the investigation. This record is intended to leave behind that narrowed boundary.
Additional investigation records 5. Temptation of false clues
At dawn, I opened the case sheet again. This time, the conclusion was obscured, leaving only the following record: “The tent was installed by digging out the snow on the slope, and it was an environment where strong winds and snow redistribution were possible.” Even events you thought you already knew reveal a completely different picture if you erase the conclusion. I lined up the locations and times and wrote down the minimum travel time. The gaps between records were not filled by imagination but were marked with empty squares. As the square grew, the reliability of the hypothesis explaining that section decreased.
Above that, I put up the hypothesis, “The explanation is that there was a chain reaction of strong winds, hypothermia, and errors in judgment in the dark.” At first everything seemed to fall into place. However, when we asked the question, “Should eye pressure and canyon falls be considered together for injuries?” a weak part of the explanation was revealed. Hypotheses must withstand questioning. If you keep bringing in new characters or coincidences to avoid questions, from that moment on, it becomes creation rather than reasoning. I used my creative sense only for the mood of the sentence and did not place it in the place of facts.
The results I got from this section are neither a definitive name for the culprit nor a complete decipherment. Instead, it became clear which explanations required fewer assumptions and which ones flipped when new discoveries were made. Even if the case cannot be closed, it is possible to narrow the scope of the investigation. This record is intended to leave behind that narrowed boundary.
Additional Investigation Record 6. Reconstruction of the final scene
At dawn, I opened the case sheet again. This time, the conclusion was obscured, leaving only the record, “Some of the members were wearing light clothing and there were traces of moving in the direction of the forest.” Even events you thought you already knew reveal a completely different picture if you erase the conclusion. I lined up the locations and times and wrote down the minimum travel time. The gaps between records were not filled by imagination but were marked with empty squares. As the square grew, the reliability of the hypothesis explaining that section decreased.
Above that, I put the hypothesis that “there was an explanation that there were external factors such as military experiments.” At first everything seemed to fall into place. However, when we asked the question, “What was the key reason why we could not return to the tent after the emergency departure?”, a weak part of the explanation was revealed. Hypotheses must withstand questioning. If you keep bringing in new characters or coincidences to avoid questions, from that moment on, it becomes creation rather than reasoning. I used my creative sense only for the mood of the sentence and did not place it in the place of facts.
The results I got from this section are neither a definitive name for the culprit nor a complete decipherment. Instead, it became clear which explanations required fewer assumptions and which ones flipped when new discoveries were made. Even if the case cannot be closed, it is possible to narrow the scope of the investigation. This record is intended to leave behind that narrowed boundary.
▲ End of investigation record — Questions still remaining
· Communications Earth & Environment — Slab avalanche model
· ETH Zurich — Dyatlov Pass study commentary
※ This article is a commentary in the form of a personal investigation record based on public records and reliable data. We distinguish between facts and inferences, and we update our judgments when new official announcements are made.
Image sources and editing
Openly licensed material from Wikimedia Commons was used by cropping, scaling, and color correcting to fit the flow of the text. Episodes with mixed generated images are not included in the list below.
- Dyatlov Pass incident 02.jpg — Anonymous Unknown author / Soviet investigators, Public domain
- Draft map of Dyatlov pass 3.png — Merikanto, CC BY-SA 4.0
- Dyatlov.Volume 1.Page 384.jpg — Лев Никитич Иванов, прокурор-криминалист Свердловской областной прокуратуры, Public domain
- Dyatlov.Volume 1.Page 386.jpg — Лев Никитич Иванов, прокурор-криминалист Свердловской областной прокуратуры, Public domain
- Dyatlov.Volume 1.Page 385.jpg — Лев Никитич Иванов, прокурор-криминалист Свердловской областной прокуратуры, Public domain
- Dyatlov.Volume 1.Page 387.jpg — Лев Никитич Иванов, прокурор-криминалист Свердловской областной прокуратуры, Public domain
- Dyatlov.Volume 1.Page 1.jpg — Василий Иванович Темпалов, прокурор города Ивдель, Public domain
- Dyatlov.Volume 1.Page 1 verso.jpg — Василий Иванович Темпалов, прокурор города Ивдель, Public domain
- Dyatlov.Volume 1.Page 301.jpg — Лев Никитич Иванов, прокурор-криминалист Свердловской областной прокуратуры, Public domain
- Dyatlov.Volume 1.Page 301 verso.jpg — Лев Никитич Иванов, прокурор-криминалист Свердловской областной прокуратуры, Public domain