A pit crater is a circular-shaped crater formed by the sinking or collapse of the ground. Fissures may erupt from the walls or base
of a pit crater, but pit craters are not constructional features built by
eruptions of lava or tephra.
Pit craters may also partially fill with lava to form a lava
lake. They are common along rift zones of shield
volcanoes; for example, Mauna Loa and Kilauea volcanoes in Hawaii.
No one has observed the formation of a large pit crater, but they are thought
to form as a consequence of the removal of support by withdrawal of underlying magma.
|Aerial view of Hi`iaka pit crater on the east rift
zone of Kilauea Volcano, Hawaii. The floor of the crater is covered
by solidified lava that poured into the crater from the lower right
(note black lava flow at crater rim). Credit: J. D. Griggs / U.S.
AND PLANETARY SCIENCE
Source: U.S. Geological Survey