Volcanism
When large scale melting occurs, the viscosity rapidly falls to 103 Pascal-seconds or even less, increasing the heat transport rate a million-fold.The decay of aluminium-26 would have significantly heated planetary embryos, but due to its short half-life (less than a million years), any traces of it have long since vanished.There are small traces of unstable isotopes in common minerals, and all the terrestrial planets, and the Moon, experience some of this heating.[6][7] Decompression melting happens when solid material from deep beneath the body rises upwards.[5] When material of a planetary body begins to melt, the melting first occurs in small pockets in certain high energy locations, for example grain boundary intersections and where different crystals react to form eutectic liquid, that initially remain isolated from one another, trapped inside rock.[3] Diapirs may also form in non-silicate bodies, playing a similar role in moving warm material towards the surface.[5] A dike is a vertical fluid-filled crack, from a mechanical standpoint it is a water filled crevasse turned upside down.[3] This model of volcanic eruption posits that magma rises through a rigid open channel, in the lithosphere and settles at the level of hydrostatic equilibrium.Despite how it explains observations well (which newer models cannot), such as an apparent concordance of the elevation of volcanoes near each other, it cannot be correct and is now discredited, because the lithosphere thickness derived from it is too large for the assumption of a rigid open channel to hold.[5] A 1988 article proposed a possibility for fractures propagating upwards from the subsurface ocean of Jupiter's moon Europa.It proposed that a fracture propagating upwards would possess a low pressure zone at its tip, allowing volatiles dissolved within the water to exsolve into gas.The elastic nature of the ice shell would likely prevent the fracture reaching the surface, and the crack would instead pinch off, enclosing the gas and liquid.The processes behind it are different to silicate volcanism because the cryomagma (which is usually water-based) is normally denser than its surroundings, meaning it cannot rise by its own buoyancy.[3][15] This splinters the surface of the lava, and the magma then collects into sacks that often pile up in front of the flow, forming a structure called a pillow.The cooling of the gas in the ash as it expands chills the magma fragments, often forming tiny glass shards recognisable as portions of the walls of former liquid bubbles.[3] A colloid of volcanic gas and magma can form as a density current called a pyroclastic flow.[21] When water turns into steam in a phreatic eruption, it expands at supersonic speeds, up to 1,700 times its original volume.[22] A phreatomagmatic eruption occurs when hot magma makes contact with water, creating an explosion.In 1912–1952, in the Northern Hemisphere, studies show that within this time, winters were warmer due to no massive eruptions that had taken place.[24] Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere.[25] Earth's Moon has no large volcanoes and no current volcanic activity, although recent evidence suggests it may still possess a partially molten core.The planet may have had a major global resurfacing event about 500 million years ago,[30] from what scientists can tell from the density of impact craters on the surface.However, radar sounding by the Magellan probe revealed evidence for comparatively recent volcanic activity at Venus's highest volcano Maat Mons, in the form of ash flows near the summit and on the northern flank.There are only two planets in the solar system where volcanoes can be easily seen due to their high activity, Earth and Io.
PlutonismVolcanoastronomical bodyradioactive decaytidal heatingpartially meltsCross sectionmantleviscosityPascal-secondsEarth's total heatplanet's formationimpactsplanetesimalsasteroid impact that caused the extinction of dinosaursdifferentiationaluminium-26half-lifeunstable isotopesterrestrial planetssilicateTritonDecompression meltingFlux meltingCryovolcanismEuropagrain boundary intersectionseutectic liquidcontact anglegrain boundariespercolationbuoyancyhydrostatic equilibriumvolcanoesvisible lightDashgil mud volcanomud volcanovolatileseffusiveHawai’i island2022 Hunga Tonga–Hunga Ha’apai eruption and tsunami.solubilityviscouscolloidvolcanic ashvesicular lavapumicevolcanic bombsvolcanic gaspyroclastic flowDione Regiophreatic eruptionphreatomagmatic eruptionclathrate hydratesEnceladus'stectonic platesdivergingconvergingmid-ocean ridgeMid-Atlantic RidgePacific Ring of FireEast African RiftWells Gray-Clearwater volcanic fieldRio Grande riftdiapirscore–mantle boundaryhotspot volcanismHawaiian hotspotsulfuric acidtropospherevolcanic wintersrillesbasaltplanetLava flowsMaat Monsash flowsOlympus MonsSolar SystemArsia MonsAscraeus MonsHecates TholusPavonis MonsMars ExpressJupitersulfursulfur dioxideGalilean moonsVoyager 2cryovolcanoesNeptuneCassini–HuygensSaturnliquid nitrogenammoniamethaneSaturnianKuiper Belt ObjectQuaoarexoplanetCOROT-7btransit29P/Schwassmann–Wachmann4 VestaBimodal volcanismExtraterrestrial liquid waterFumaroleGas lawsGeology of CeresGeology of MercuryGeology of PlutoGeyserGlaciovolcanismHotspotHydrothermal ventIgneous rockIntraplate volcanismLava planetMagma oceanMagmatismMantle plumePlate tectonicsPrediction of volcanic activitySeafloor spreadingVolcanic arcVolcanic rock