A structure out of place
Deep in the Siberian taiga, on the slope of the Patom Highlands, sits a geological formation that is difficult to explain. The Patomskiy Crater is a massive cone of shattered grey limestone blocks, rising about 40 meters (130 ft) high with a base diameter of around 160 meters (520 ft). Its total volume is estimated to be between 230,000 and 250,000 cubic meters, weighing approximately one million tons. The structure is remarkably fresh, with steep slopes and little soil development. At its top, a ring-shaped crown surrounds a central, smaller mound that is about 12 meters (39 ft) high.
Russian geologist Vadim Kolpakov was the first scientist to document the crater in 1949, though it was already known to the local Yakut people. They call it "Fire Eagle's Nest" and have long considered it a cursed place that animals avoid and where people can fall ill or disappear. Kolpakov initially struggled to classify the cone, which appeared on no geological maps. It resembled a volcano, yet the region has not been volcanically active for millions of years, and no volcanic materials have ever been found at the site.
Competing scientific explanations
The crater's origin is a subject of intense scientific debate. Early hypotheses centered on a meteorite impact, perhaps a fragment from the 1908 Tunguska event. This theory has been largely discarded because the site lacks any meteorite fragments, shock metamorphism in the rock, or other typical impact evidence. After a 2010 scientific conference, most experts formally rejected the meteoric hypothesis.
More recent theories point to an endogenous, or internal, origin. One leading explanation is a phreatic explosion, a steam-driven eruption caused when magma or another heat source interacts with groundwater, violently flashing it to steam. This could have shattered and ejected the limestone from below without producing lava. Another possibility is the explosive release of a deep pocket of pressurized gas, such as methane or hydrogen. This "gas volcano" theory could account for the structure's formation without the high temperatures associated with magma. Dendrochronology, the study of tree rings, suggests the crater formed around 300 to 350 years ago. Trees in the vicinity also show periods of accelerated growth, which has led to theories about radiation, though tests have only revealed low levels of radioactivity.