Facebook icon
Twitter icon
TeacherTube icon
Pinterest icon

When tensional faults crack open and grabens form, pit craters often occur along the faults. These are caused by the surface rock collapsing into empty subsurface voids. Pit craters can occur alone and in groups. If enough of them form close together, they may merge into an elongated depression. Scientists can tell a pit crater from an impact crater because pit craters typically have no upraised rim as impact craters do.

Pit craters can also develop where lava tubes run. If the lava in the tube drains away, it leaves the tube roof unsupported. Parts of it may fall in, making a hole or a pit along the lava tube's path.


Pit craters often form on volcanoes. Some occur along fractures and faults, others along subsurface lava channels called lava tubes. After the lava drains away, parts of a lava tube's roof will collapse under its own weight. This image shows fracture-related pits running north-south, and an east-west set of pits that probably track an underground lava tube. (NASA/JPL-Caltech/Arizona State University)
Pit Craters
(NASA/JPL-Caltech/Arizona State University)