A pit crater (also called a subsidence crater or collapse crater) is a depression formed by a sinking or collapse of the surface lying above a void or empty chamber, rather than by the

eruption Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...

of a

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or ...

vent Vent or vents may refer to: Science and technology Biology *Vent, the cloaca region of an animal * Vent DNA polymerase, a thermostable DNA polymerase Geology *Hydrothermal vent, a fissure in a planet's surface from which geothermally heated wate ...

. Pit craters are found on Mercury,

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

, and the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

. Pit craters are often found in a series of aligned or offset chains and in these cases, the features is called a pit crater chain. Pit crater chains are distinguished from catenae or

crater chain A crater chain is a line of craters along the surface of an astronomical body. The descriptor term for crater chains is catena , plural catenae (Latin for "chain"), as specified by the International Astronomical Union's rules on planetary nome ...

s by their origin. When adjoining walls between pits in a pit crater chain collapse, they become troughs. In these cases, the craters may merge into a linear alignment and are commonly found along extensional structures such as fractures, fissures and graben. Pit craters usually lack an elevated rim as well as the ejecta deposits and

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

s that are associated with

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact crater ...

s.Okubo, Chris, and Stephen Martel. "Pit crater formation on Kilauea volcano, Hawaii." Journal of Volcanology and Geothermal Research. 86.1-4 (1998):1-18. Print. Pit craters are characterized by vertical walls that are often full of fissures and vents. They usually have nearly circular openings.Geological Field Guide: Kilauea Volcano. revised edition. Claremont, CA: Hawai'i Natural History Association, 2002. 97. Print As distinct from impact craters, these craters are not formed from the clashing of bodies or projectiles from space. Rather, they can be formed by a

explosion from a bottled up

(the explosion leaving a shallow

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

) or when the ceiling over a void is not solid enough to prevent collapse of the overlying material. Pit craters can also result from collapse of

lava tube A lava tube, or pyroduct, is a natural conduit formed by flowing lava from a volcanic vent that moves beneath the hardened surface of a lava flow. If lava in the tube empties, it will leave a cave. Formation A lava tube is a type of lava ...

s or dikes, or from collapsed

magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it up ...

s under loose material. A newly formed pit crater has steep overhanging sides and is shaped inside like an inverted cone, growing wider closer to the bottom. Over time the overhangs fall into the pit and the crater fills with talus from the collapsing sides and roof. A middle-aged pit crater is cylindrical but its rim will continue to collapse, resulting in the crater's expanding outward until it resembles a funnel or drain—narrower at the bottom than the top. While pit craters and calderas form through similar processes, the former term is usually reserved for smaller features of a mile or less in diameter. The term "pit crater" was coined by C. Wilkes in 1845 to describe craters along Hawaii's East Rift Zone. Hawaii is known for its volcanoes and pit craters. In 1868 an eyewitness saw more than two-thirds of the basin of Kilauea cave in and fill with a

lava lake Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (someti ...

. This process happened repeatedly. The modern Halema'uma'u Shield began growing and then collapsed into a deep funnel-shaped pit. This pit filled with lava and for 19 years burned continuously, becoming famous as the Hawaiian Fire Pit. In 1924 the lava lake emptied when the walls of the crater cracked and collapsed and filled with water that turned to steam. After a week and a half Halema'uma'u had widened and was 1,700 feet deep. Rocks that were blasted away from the crater can still be seen on the caldera floor. 300px, Western rim of Devil's Throat pit crater in June 2016 Devil's Throat (pictured at right) is another good Hawaiian example of a pit crater, especially since we were able to observe its formation through collapse over time. It was first documented by Thomas Jaggar who estimated its dimensions as 15m x 10.5m x 75m. In 1923 William Sinclair was lowered into Devil's Throat on a rope. He found a cavern shaped like an upside down funnel which widened as he approached the bottom. He measured the floor as about 60m in diameter and the crater's depth around 78m. The crater's mouth widened over time and in 2006 the crater's dimensions were measured as 50m x 42m x 49m. This growth is explained by observing pieces of the overhanging roof breaking off and falling to the bottom. These shards gradually piled up on the crater floor, reducing its depth.USGS. Devil's Throat has evolved into a shadow of its former self, web. 7 Oct 201

/ref> The process also happens on the surface of

and other terrestrial planets. Features resembling pit craters have been observed on Mercury (planet), Mercury.

References

External links

Halema'uma'u CraterUSGS page on pit craters
* {{DEFAULTSORT:Pit Crater Volcanism Volcanic landforms Volcanic craters