Which landforms can develop when ice-rich permafrost thaws?

When ice-rich permafrost thaws, the resulting ground settlement and loss of structural integrity create a landscape known as thermokarst. This process produces an uneven, hummocky surface that shares characteristics with the karst topography found in limestone regions.12

Specific landforms that develop due to this thawing include:

• Depressions and Lakes: Thawed depressions, often referred to as thaw lakes, thermokarst lakes, or cave-in lakes, are common in areas underlain by perennially frozen silt.1
• Surface Irregularities: The ground may develop small pits, sinkholes, and steep-walled ravines.12
• Mounds: Thermokarst mounds are circular or polygonal hummocks that form when the ice within a polygonal network melts, leaving the inner-ice areas elevated.1
• Subsurface Features: The melting of ground ice can create tunnels and caverns. These may exist as undetected voids for years before the surface roof collapses, which can pose significant hazards to construction and agriculture.12

These features are primary indicators of ice-rich permafrost and are often triggered by natural or artificial vegetation removal or broader climatic warming.12