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Pressure Ridge (lava)
In volcanology, a pressure ridge or a tumulus (plural: tumuli), and rarely referred to as a schollendome, is sometimes created in an active lava flow. Formation occurs when the outer edges and surfaces of the lava flow begin to harden. If the advancing lava underneath becomes restricted it may push up on the hardened crust, tilting it outward. Inflation also takes place and is a process where the plastic layer of lava underneath expands as it cools and small crystals form. The end result is a raised mound of hardened lava rock, usually a relatively narrow but long ridge. Tension cracks form on the surface of pressure ridges and run along the axis An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to: Mathematics * Axis of rotation: see rotation around a fixed axis * Axis (mathematics), a designator for a Cartesian-coordinat ... of elongated ridges, and at both edges of broader ridges, sometimes referred to as pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanology
Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma and related geological, geophysical and geochemical phenomena (volcanism). The term ''volcanology'' is derived from the Latin word ''vulcan''. Vulcan was the ancient Roman god of fire. A volcanologist is a geologist who studies the eruptive activity and formation of volcanoes and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra (such as ash or pumice), rock and lava samples. One major focus of enquiry is the prediction of eruptions; there is currently no accurate way to do this, but predicting eruptions, like predicting earthquakes, could save many lives. Modern volcanology image:Icelandic tephra.JPG, Volcanologist examining tephra horizons in south-central Iceland. In 1841, the first volcanological observatory, the Vesuvius Observatory, was founded in the Kingdom o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is also often called ''lava''. A lava flow is an outpouring of lava during an effusive eruption. (An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. The word ''lava'' comes from Italian and is probably derived from the Latin word ''labes'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasticity (physics)
In physics and materials science, plasticity, also known as plastic deformation, is the ability of a solid material to undergo permanent Deformation (engineering), deformation, a non-reversible change of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the material itself. In engineering, the transition from Elasticity (physics), elastic behavior to plastic behavior is known as Yield (engineering), yielding. Plastic deformation is observed in most materials, particularly metals, soils, Rock (geology), rocks, concrete, and foams. However, the physical mechanisms that cause plastic deformation can vary widely. At a crystalline scale, plasticity in metals is usually a consequence of dislocations. Such defects are relatively rare in most crystalline materials, but are numerous in some and part of their crystal structure; in such cases, plastic crystallinity can res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are usually identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations. The scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification. The word ''crystal'' derives from the Ancient Greek word (), meaning both "ice" and "rock crystal", from (), "icy cold, frost". Examples of large crystals include snowflakes, diamonds, and table salt. Most inorganic solids are not crystals but polycrystals, i.e. many microscopic crystals fused together into a single solid. Polycrystals include most metals, rocks, ceramics, and ice. A third category of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tension (physics)
In physics, tension is described as the pulling force transmitted axially by the means of a string, a rope, chain, or similar object, or by each end of a rod, truss member, or similar three-dimensional object; tension might also be described as the action-reaction pair of forces acting at each end of said elements. Tension could be the opposite of compression (physics), compression. At the atomic level, when atoms or molecules are pulled apart from each other and gain potential energy with a restoring force still existing, the restoring force might create what is also called tension. Each end of a string or rod under such tension could pull on the object it is attached to, in order to restore the string/rod to its relaxed length. Tension (as a transmitted force, as an action-reaction pair of forces, or as a restoring force) is measured in newton (unit), newtons in the International System of Units (or pounds-force in Imperial units). The ends of a string or other object transmitt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Ridge
A pressure ridge is a topographic ridge produced by compression. Depending on the affected material, "pressure ridge" may refer to: * Pressure ridge (ice), between ice floes * Pressure ridge (lava), in a lava flow * Pressure ridge (seismic), in a fault zone In a seismic context, a pressure ridge can range in size from a few-metres-long mound, to a kilometres-long lateral ridge. It is the result of one or several earthquakes occurring on certain types of fault geometries, such as compressional bends or stepovers along strike-slip faults. A pressure ridge can for instance be the result of a deep-set obstruction on the fault plane, which leads to material being pushed up during earthquakes. See also * Ridge (meteorology) A ridge or barometric ridge is a term in meteorology describing an elongated area of relatively high atmospheric pressure compared to the surrounding environment, without being a closed circulation. It is associated with an area of maximum anticy ..., an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflection Symmetry
In mathematics, reflection symmetry, line symmetry, mirror symmetry, or mirror-image symmetry is symmetry with respect to a reflection. That is, a figure which does not change upon undergoing a reflection has reflectional symmetry. In 2D there is a line/axis of symmetry, in 3D a plane of symmetry. An object or figure which is indistinguishable from its transformed image is called mirror symmetric. In conclusion, a line of symmetry splits the shape in half and those halves should be identical. Symmetric function In formal terms, a mathematical object is symmetric with respect to a given operation such as reflection, rotation or translation, if, when applied to the object, this operation preserves some property of the object. The set of operations that preserve a given property of the object form a group. Two objects are symmetric to each other with respect to a given group of operations if one is obtained from the other by some of the operations (and vice versa). The symm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Cave
A lava cave is any cave formed in volcanic rock, though it typically means caves formed by volcanic processes, which are more properly termed volcanic caves. Sea caves, and other sorts of erosional and crevice caves, may be formed in volcanic rocks, but through non-volcanic processes and usually long after the volcanic rock was emplaced. Types There are many types of lava caves, with these being the most notable: *Lava tubes are the most common and extensive type of lava cave. Lava tubes usually form in pahoehoe lava flows, though exceptions exist. As the lava is emitted from the vent area, it spreads in the path of least resistance. The outer layers of the lava harden, while the interior forms horizontal conduits that channel the advance of the flow. These conduits are the beginning stages of lava tubes that serve to insulate the heat from the lava which then provides a way for the lava flow to advance longer distances. Dependent upon the slope, terrain, and lava viscosity, diffe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Caves
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 underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is also often called ''lava''. A lava flow is an outpouring of lava during an effusive eruption. (An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. The word ''lava'' comes from Italian and is probably derived from the Latin word ''labes'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
