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Often, a volcano may have a deep magma chamber many kilometers down, which supplies a shallower chamber near the summit. The location of magma chambers can be mapped using seismology : seismic waves from earthquakes move more slowly through liquid rock than solid, allowing measurements to pinpoint the regions of slow movement which identify ...
Diagram of the Yellowstone Caldera. The Lava Creek eruption of the Yellowstone Caldera, which occurred 640,000 years ago, [112] ejected approximately 1,000 cubic kilometres (240 cu mi) of rock, dust and volcanic ash into the atmosphere. It was Yellowstone's third and most recent caldera-forming eruption.
Augustine Volcano (Alaska) during its eruptive phase on January 24, 2006. A volcano is commonly defined as a vent or fissure 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.
Mount Mazama's eruption timeline, an example of caldera formation. A caldera (/ k ɔː l ˈ d ɛr ə, k æ l-/ [1] kawl-DERR-ə, kal-) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption.
A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers of hardened lava and tephra. [1] Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and explosive eruptions. [2] Some have collapsed summit craters called calderas. [3]
Cinder cones are also commonly found on the flanks of shield volcanoes, stratovolcanoes, and calderas. [3] For example, geologists have identified nearly 100 cinder cones on the flanks of Mauna Kea, a shield volcano located on the island of Hawaii. [3] Such cinder cones likely represent the final stages of activity of a mafic volcano. [11]
Submarine volcanoes are underwater vents or fissures in the Earth's surface from which magma can erupt. Many submarine volcanoes are located near areas of tectonic plate formation, known as mid-ocean ridges. The volcanoes at mid-ocean ridges alone are estimated to account for 75% of the magma output on Earth. [1]
Volcanoes known to have Surtseyan activity include: Surtsey, Iceland. The volcano built itself up from depth and emerged above the Atlantic Ocean off the coast of Iceland in 1963. Initial hydrovolcanics were highly explosive, but as the volcano grew, rising lava interacted less with water and more with air, until finally Surtseyan activity ...