Earth Oddities · Ground Collapse & Surface Deformation
The ground beneath our feet is not always as solid as it appears. Underground
cavities can collapse without warning, sediment can compact gradually, frozen
ground can thaw and entire rivers or lakes can disappear into hidden drainage
systems.
This Earth Oddities sub-hub explores the processes that make land sink,
fracture, collapse or drain—from classic limestone sinkholes and slow regional
subsidence to giant earth fissures, disappearing waters and thermokarst in
thawing permafrost.
Key distinction: Sinkholes are localized collapses or
depressions commonly associated with underground cavities. Land subsidence
is the broader downward movement of the ground and may affect areas ranging
from a single property to an entire region.
Explore Sinkholes, Subsidence and Ground Collapse
Sinkholes Explained
Discover how underground cavities form and collapse, creating dolines,
cenotes, cover-collapse sinkholes and enormous holes capable of swallowing
roads, buildings and vehicles.
Land Subsidence Explained
Learn why the ground slowly sinks through groundwater withdrawal, sediment
compaction, mining, hydrocarbon extraction, drainage and natural geological
processes.
Earth Fissures & Ground Cracks Explained
Understand how subsidence, fault movement, soil shrinkage and uneven ground
deformation create long fractures that can cut across deserts, fields,
roads and communities.
Disappearing Rivers & Lakes Explained
Explore how rivers, ponds and lakes vanish into sinkholes, fractures,
lava tubes, caves and underground drainage networks—and why some later
return.
Permafrost Collapse & Thermokarst Explained
See how thawing ground ice causes Arctic landscapes to sink, slump and
fracture, forming thermokarst lakes, thaw pits, collapsing ice wedges,
giant thaw slumps and rare features such as the Yamal craters.
How These Ground-Failure Processes Differ
| Process | Main cause | Typical result |
|---|---|---|
| Sinkhole | Collapse or subsidence above an underground cavity | Localized circular or irregular depression |
| Land subsidence | Compaction, fluid withdrawal, mining or natural consolidation | Gradual regional lowering of the ground |
| Earth fissure | Differential subsidence, tectonics or soil contraction | Long surface crack or open fracture |
| Disappearing water | Drainage into caves, fractures, sinkholes or permeable ground | Sudden or seasonal loss of a river or lake |
| Thermokarst | Thawing of ice-rich permafrost | Subsidence, ponds, lakes and thaw slumps |
Frequently Asked Questions
Are sinkholes and land subsidence the same thing?
No. A sinkhole is usually a localized depression related to an underground
void or soluble rock. Land subsidence is the broader downward movement of
the ground and may extend across a large region.
Can land subsidence create earth fissures?
Yes. When adjoining areas sink at different rates, stress can tear the
surface apart and create long earth fissures.
Why do rivers and lakes suddenly disappear?
Water may escape through sinkholes, fractures, cave systems, lava tubes,
porous sediment or newly opened underground drainage routes.
Is thermokarst a type of sinkhole?
Not usually. Thermokarst forms when ground ice melts and the surface
subsides. Limestone sinkholes form mainly through rock dissolution and
cavity collapse.
