Volcanic crater in the context of "Mount Zaō"

A caldera (/kɔːlˈdɛrə, kæl-/ kawl-DERR-ə, kal-) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. The ejection of large volumes of magma in a short time can upset the integrity of a magma chamber's structure by in effect removing much of the chamber's filling material. The walls and ceiling of a chamber may now not be able to support its own weight and any substrate or rock resting above. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface that may have a diameter of dozens of kilometers. Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur over the course of a century, the formation of a caldera is a rare event, occurring only a few times within a given window of 100 years. Only nine caldera-forming collapses are known to have occurred between 1911 and 2022, with the caldera collapses at Kīlauea, Hawaii, in 2018 and Hunga Tonga–Hunga Haʻapai in 2022 being the most recent. Volcanoes that have formed a caldera are sometimes described as "caldera volcanoes".

Rupite (Bulgarian: Рупите, pronounced [ˈrupitɛ]) is a village which includes a small mountainous protected area in the southeastern part of Blagoevgrad Province, Bulgaria, 11 kilometers northeast of Petrich, Petrich Municipality, on the western bank of the Struma River. It is best known as the place where alleged Bulgarian clairvoyant Baba Vanga lived. The area is also associated with the crater of an extinct volcano, the hills of Kozhuh and Pchelina, and the warm thermal springs. The village has 1,124 inhabitants.

Kronotsky (Russian: Кроноцкая сопка, Kronotskaya Sopka) is a major stratovolcano on the Kamchatka Peninsula, Russia. It is located in Kronotsky Nature Reserve to the east of Lake Kronotskoye (the largest freshwater lake in Kamchatka). It has a particularly symmetrical conical shape, comparable to Mount Fuji in Japan and to Mayon Volcano in the Philippines. The summit crater is plugged by a volcanic neck, and the summit itself is ice-capped. It exhibits the classic radial drainage pattern, extending downward from its crater. Kronotsky is considered to be one of the most scenic volcanoes in Kamchatka. In the 20th century, the volcano had low activity, with occasional weak phreatic eruptions. Its latest eruption started on October 4, 2025, with an ash cloud up to 9 km (5.6 mi) high.

A volcanogenic lake is a lake formed as a result of volcanic activity. They are generally a body of water inside an inactive volcanic crater (crater lakes) but can also be large volumes of molten lava within an active volcanic crater (lava lakes) and waterbodies constrained by lava flows, pyroclastic flows or lahars in valley systems. The term volcanic lake is also used to describe volcanogenic lakes, although it is more commonly assigned to those inside volcanic craters.

An impact crater is a depression in the surface of a solid astronomical body formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Impact craters are typically circular, though they can be elliptical in shape or even irregular due to events such as landslides. Impact craters range in size from microscopic craters seen on lunar rocks returned by the Apollo Program to simple bowl-shaped depressions and vast, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth.

Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede, and most small moons and asteroids. On other planets and moons that experience more active surface geological processes, such as Earth, Venus, Europa, Io, Titan, and Triton, visible impact craters are less common because they become eroded, buried, or transformed by tectonic and volcanic processes over time. Where such processes have destroyed most of the original crater topography, the terms impact structure or astrobleme are more commonly used. In early literature, before the significance of impact cratering was widely recognised, the terms cryptoexplosion or cryptovolcanic structure were often used to describe what are now recognised as impact-related features on Earth.

Kahoʻolawe is the smallest of the eight main volcanic islands of the Hawaiian Islands. Unpopulated, it lies about seven miles (11 km) southwest of Maui. The island is 11 mi (18 km) long by 6.0 mi (9.7 km) wide, with a total land area of 44.97 sq mi (116.47 km). Its highest point is the crater of Lua Makika, at the summit of Puʻu Moaulanui, about 1,477 feet (450 m) above sea level.

Kahoʻolawe is relatively dry, with an average annual rainfall of less than 26 in (66 cm) resulting from a combination of being too low to generate much orographic precipitation from the northeastern trade winds and lying in the rain shadow of eastern Maui's 10,023-foot-high (3,055 m) volcano, Haleakalā. More than one quarter of Kahoʻolawe has been eroded down to saprolitic hardpan soil, largely on exposed surfaces near the summit.

A Hawaiian eruption is a type of volcanic eruption where lava flows from the vent in a relatively gentle, low level eruption; it is so named because it is characteristic of Hawaiian volcanoes. Typically they are effusive eruptions, with basaltic magmas of low viscosity, low content of gases, and high temperature at the vent. Very small amounts of volcanic ash are produced. This type of eruption occurs most often at hotspot volcanoes such as Kīlauea on Hawaii's big island and in Iceland, though it can occur near subduction zones (e.g. Medicine Lake Volcano in California) and rift zones. Hawaiian eruptions may occur along fissure vents, such as during the eruption of Mauna Loa in 1950, or at a central vent, such as during the 1959 eruption in Kīlauea Iki Crater, which created a lava fountain 580 meters (1,900 ft) high and formed a 38-meter cone named Puʻu Puaʻi. In fissure-type eruptions, lava spurts from a fissure on the volcano's rift zone and feeds lava streams that flow downslope. In central-vent eruptions, a fountain of lava can spurt to a height of 300 meters or more (heights of 1600 meters were reported for the 1986 eruption of Mount Mihara on Izu Ōshima, Japan).

Hawaiian eruptions usually start from an increase earthquake activity in a localized region followed with the formation of cracks in the ground from which a curtain of incandescent lava or several closely spaced lava fountains appear. The lava can overflow the fissure and form ʻaʻā or pāhoehoe style of flows. When such an eruption from a central cone is protracted, it can form lightly sloped shield volcanoes, for example Mauna Loa or Skjaldbreiður in Iceland. Geologists can predict where new eruptions will take place by tracking the earthquakes that precede the eruptions.

A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, occurs when magma heats ground water or surface water. The extreme temperature of the magma (anywhere from 500 to 1,170 °C (930 to 2,100 °F)) causes near-instantaneous evaporation of water to steam, resulting in an explosion of steam, water, ash, rock, and volcanic bombs. At Mount St. Helens in Washington state, hundreds of steam explosions preceded the 1980 Plinian eruption of the volcano. A less intense geothermal event may result in a mud volcano.

Phreatic eruptions typically include steam and rock fragments; the inclusion of liquid lava is unusual. The temperature of the fragments can range from cold to incandescent. If molten magma is included, volcanologists classify the event as a phreatomagmatic eruption. These eruptions occasionally create broad, low-relief craters called maars. Phreatic explosions can be accompanied by carbon dioxide or hydrogen sulfide gas-emissions. Carbon dioxide can asphyxiate at sufficient concentration; hydrogen sulfide acts as a broad-spectrum poison. A 1979 phreatic eruption on the island of Java killed 140 people, most of whom were overcome by poisonous gases.

Beerenberg is a stratovolcano dominating the northeastern end of the Norwegian island of Jan Mayen. It is 2,277 m (7,470 ft) high and is the world's northernmost subaerial active volcano and the only active volcano in Norway. The volcano is topped by a mostly ice-filled crater about one kilometre (5⁄8 mile) wide, with numerous peaks along its rim including the highest summit, Haakon VII Toppen, on its western side.