Patom crater is an unusual pale cone rising from a forested slope in eastern Siberia. Its name suggests an impact hollow, but the prominent feature is a pile of broken rock with a ring-shaped depression and a smaller central mound. Since its scientific discovery in 1949, researchers have debated whether an impact, deep gases, heated water or freezing groundwater produced it. Published fieldwork has replaced much of the speculation with measurements, while leaving important disagreement about the mechanism.
A geological object with an unusual shape
In their 2008 geological and geochemical paper, Viktor Antipin and Alexander Fedorov describe a structure in Bodaibo District, Irkutsk Oblast, largely built from fragmented limestone. Their mapping distinguishes an outer slope, ring swell, trench and central mound, with differences in weathering and rock distribution interpreted as successive stages of construction.
Their 2006 expedition supplied a detailed geological map and analyses of rocks within and outside the cone. They argued against a single meteoritic impact, citing the structure’s staged development and the absence of a convincing meteoritic chemical signature in the samples examined. Their proposed alternative involved gases and fluids rising from depth. These conclusions belong to those researchers and the material they studied; the word “crater” does not itself identify an impact origin.
What the tree rings add
The original Russian 2020 paper by Vladimir Voronin, Antipin, Vladimir Oskolkov and Fedorov reports 30 larch cross-sections collected in 2006 and 2008, supplemented by 40 cores from trees in the surrounding forest. Cross-dating connected growth patterns with calendar years. This is more informative than treating the age of one tree as the date of the entire landform.
The authors infer an initial formative period around the late fifteenth to early sixteenth century, with a later disturbance recorded around 1841–1842. Mechanical damage and changes in growth are central to that reconstruction. They also discuss increased strontium in wood associated with the mid-nineteenth century, interpreting the combined evidence in favour of heated fluids and a steam-driven, or phreatic, process.
That reconstruction makes a simple connection with the 1908 Tunguska explosion difficult: the cone’s history, in their interpretation, began much earlier. It does not turn an inferred episode of ground movement into an eyewitness account of an explosion. The age of a surviving tree constrains part of a landscape’s history, while the cause of the disturbance still requires geological interpretation.
The freezing-ground alternative
Vladimir Alekseyev offered another developed model in Cryovolcanism and the mystery of the Patom cone, published in 2012. He compared the landform with structures produced by freezing water-bearing ground. In this model, repeated freezing and deformation of fractured bedrock help raise the cone; spreading and subsidence of ice-rich debris help produce the hollow, surrounding ridges and central hill.
Alekseyev also cautioned against reading sparse vegetation or relatively fresh-looking rubble as a direct measure of youth. His discussion left the age question open. This approach differs from an account centred on hot fluids or steam, even though both are geological explanations. Calling either a “volcano” without explaining what is meant can conceal that difference: freezing-related heave is not an eruption of molten lava.
The comparison is useful because it asks how the entire shape could develop, rather than attaching a dramatic explanation to its appearance alone. Similarity is a starting point for a model; deciding between models requires evidence about the rocks, subsurface structure, water and temperature history.
Gravity measurements and a newer combined model
In Dmitry Demezhko’s first-person account published by the European Geosciences Union in 2014, he describes an August 2010 gravity survey. His team found an unusually low-gravity pattern with deeper structure, differing from the comparison impact structure at Popigai. He proposed two stages: creation of a porous channel followed by freezing-related processes that helped break the rock and build the cone.
Demezhko’s account also addresses the site’s reputation. He reports encountering no mystical effects during the work and describes a chipmunk living in the crater, despite stories that animals avoid it. This modest field observation does not settle the geological origin, but it illustrates the difference between a reported local reputation and what a particular expedition actually observed.
The publisher’s abstract of Demezhko’s 2025 paper presents gravity and magnetotelluric results and a gaseous–cryogenic hypothesis. It describes a negative gravity anomaly of about 0.6 mGal and a lower-density zone with narrower channels, including one reaching the surface beneath the cone. The proposed sequence begins with gas creating a permeable fractured zone, followed by precipitation-derived water entering frozen ground.
Only that paper’s public abstract was available for this review, not its complete subscription text. It supports reporting a newer published model and the measurements summarised by its author; it does not justify claiming that every methodological detail or uncertainty in the full paper was examined.
What the evidence does and does not establish
The reviewed sources give substantial reasons to investigate Patom as a geological structure. They do not provide a recovered spacecraft, an authenticated extraterrestrial object or a witnessed formation event. The main scientific questions concern how gas, water, fractures, heat and freezing may have interacted, and when different parts developed.
Differences between the studies also matter. A mapped surface sequence, a chemical analysis, a tree-ring disturbance and a gravity anomaly measure different things. Combining them can strengthen a model, but an anomaly does not uniquely identify the object or process producing it. Nor should rejection of a simple impact explanation be presented as automatic proof of one particular alternative.
Map, photograph and access
The pin uses the documented object location on the Commons photograph record, rounded to a general cone reference. It is not a surveyed sample point, safe landing place or visitor route. A source-backed current public-access arrangement was not established, so no public-place access claim is made.
The aerial image is credited to Dmitry Semenov by EGU and licensed for reuse under CC BY 4.0. It shows the actual landform, rather than reconstructing how it formed. Its 2014 publication date is not treated as a verified capture date. A separate panorama by another photographer carries a non-commercial restriction and was not selected.
Assessment and further reading
The outcome is Disputed, referring to the competing published geological models for the cone’s formation. The reviewed studies support a natural research problem, while differing over the mechanism and its stages; they do not establish a paranormal cause. No single year is assigned to formation. Discovery, fieldwork and publication dates are kept separate from the inferred history of the landform.
For a different Siberian case with a securely dated event, see the Tunguska reference. Patom’s tree-ring evidence is one reason the two should not be merged into a single incident. Sources and rights checked 13 November 2026.