How Does Caldera Form

The volcanic activity of Mars is concentrated in two large provinces: Tharsis and Elysium. Each province contains a series of giant shield volcanoes similar to those we see on Earth, likely the result of mantle hotspots. The surfaces are dominated by lava flows and all have one or more collapse calderas [38] Mars has the largest volcano in the solar system, Olympus Mons, which is more than three times higher than Mount Everest, with a diameter of 520 km (323 miles). The top of the mountain has six nested calderas. [41] A caldera is a large depression created when a volcano erupts and collapses. Because a silicon caldera can erupt hundreds, if not thousands, of cubic kilometers of material in a single event, it can have catastrophic environmental impacts. Even small calder-forming eruptions, such as Krakatau in 1883[27] or Mount Pinatubo in 1991,[28] can cause considerable local destruction and a noticeable drop in temperature worldwide. Large calderas can have an even greater impact. The ecological impact of the eruption of a large caldera can be seen in the account of the eruption of Lake Toba in Indonesia. Calderas are among the most spectacular objects on earth.

These are large volcanic craters that form in two different ways: 1) an explosive volcanic eruption; or, 2) collapse of the surface rock in an empty magma chamber. Collapse calderas are formed when a large magma chamber is emptied by a volcanic eruption or by an underground magmatic movement. The cantilevered rock that forms the roof of the magma chamber then collapses, forming a large crater. It is believed that Crater Lake and many other calderas were formed by this process. The mixture of ash and volcanic gases first rises into the atmosphere as an eruption column. However, as the volume of eruptive material increases, the eruption column is unable to carry enough air to remain floating, and the eruption column collapses into a tephra fountain that falls to the surface to form pyroclastic flows. [18] Eruptions of this type can spread ash over large areas, so ash tuffs replaced by siliceous caldera eruptions are the only volcanic product whose volumes rival those of basaltic floods. [10]: 77 For example, when the Yellowstone caldera last burst about 650,000 years ago, it released about 1,000 km3 of material (measured in dense rock equivalent (DRE)) that covered a significant portion of North America with up to two meters of debris. [19] Crater Lake National Park in Oregon, United States, is a former caldera. This page is no longer active and all the magma has been ejected. Toba Caldera: Landsat GeoCover image of the caldera formed by the Toba supervolcano.

Today it is the largest volcanic lake in the world. The image above was created using NASA`s Landsat GeoCover data. Enlarge image. Calderas like Crater Lake and those in Yellowstone National Park result from spectacular eruptions, but slower eruptions can also create calderas as well. This often happens with shield volcanoes, which are usually shallower and gradually tilted. Lava flows from shield volcanoes more slowly and often at regular intervals. Over time, this creates a series of interlocking depressions. The Kilauea caldera on Mount Kilauea, one of the volcanoes that make up Hawaii, is an example. A caldera (/kɔːlˈdɛrə, kæl-/[1] kawl-DERR-ə, kal-) is a large cauldron-shaped hollow that forms shortly after a magma chamber is emptied during a volcanic eruption. When large amounts of magma erupt over a short period of time, the structural support of the rock above the magma chamber is lost. The surface of the ground then collapses into the emptied or partially emptied magma chamber, leaving a large depression on the surface (from one to tens of kilometers in diameter).

[2] Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed by subsidence and collapse rather than by an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event that occurs only a few times a century. [3] Between 1911 and 2016, only seven calder-forming collapses are known. [3] More recently, a caldera collapse occurred in Kīlauea, Hawaii, in 2018. [4] If magma continues to be injected into the collapsed magma chamber, the center of the caldera can be lifted in the form of a resurgent dome, as seen in the Valles caldera, Lake Toba, the San Juan volcanic field,[6] Cerro Galán,[25] Yellowstone,[26] and many other calderas. [6] The caldera of Valles owes its name to the ecology and geology of this relief.