How can thawing permafrost create hidden underground caverns?

Thawing permafrost creates hidden underground caverns primarily through the melting of ground ice, a process that contributes to the formation of thermokarst topography.

When large masses of ground ice—such as ice wedges or other segregated ice—melt due to natural or artificial causes, the volume of the subsurface material decreases, leaving behind voids. In some cases, these openings can exist as undetected caverns beneath the surface for many years before the ground above them eventually collapses. This process is particularly common in areas underlain by perennially frozen silt, where the melting of ice-rich permafrost leads to the development of various features, including tunnels, sinkholes, and deep pits.1

These formations are a significant concern for human activity, as the sudden collapse of these hidden caverns poses a danger to construction and agricultural projects. The resulting landscape often resembles the karst topography typically found in limestone regions, characterized by an uneven, hummocky surface.1