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220 Cards in this Set
- Front
- Back
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adiabatic
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the thermodynamic process of expanding or compressing a substance without allowing it to exchange heat with its surroundings
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amphibole
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rock-forming silicate mineral that contains Fe, Mg, Al, Ca, Na, Ti, and ~ 1.5 % H2O
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assimilation
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the incorporation of material originally present in surrounding wallrock into a magma.
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asthenosphere
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the part of the upper mantle beneath the lithosphere that deforms by plastic flow as a result of high temperatures at depth in the earth
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clinopyroxene
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rock-forming silicate mineral. in mantle peridotite, most of the Na2O, TiO2, and Al2O in the rock is contained in this mineral
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crust
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the part of the earth lying above the mohoveric discontinuity. continental crust varies from 30 to 80km in thickness and oceanic crust varies from 6 to 20km in thickness
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fractional crystallization
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crystallization of minerals from a silicate liquid (magma) during cooling causes the liquid to change composition. the possible compositional variations that can occur through this process are governed by thermodynamic state functions for the crystal and melt
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latent heat of melting / latent heat of crystallization
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heat of reaction required to accomplish the phase change from solid to liquid form
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liquidus volume
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the range of composition for a liquid solution over which a particular solid is in the liquidus phase
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lithosphere
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the portion of the earth's crust and upper mantle above the asthenosphere that is rigid and deforms by brittle failure as a result of low temperatures
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magma
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molten rock that consists of up to three components: liquid silicate melt, suspended crystalline solids, and gas bubbles.
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magma mixing
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the mixing of two magmas to form a hybrid. such a process presents the immediate problems of how the two magmas were produced and what caused them to remain separate and then to mix
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mantle
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the portion of the earth's interior lying below the mohoveric discontinuity and above the outer core. divided into an upper mantle that extends to a depth of ~400km, a transition zone extending to ~670km, and a lower mantle that extends to the core-mantle boundary at ~2900km
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melt reaction coefficient
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the proportion of a crystalline phase that is reacted during melting. positive reaction coefficients indicate that the solid is consumed during melting. negative indicate that the solid is produced along with the melt phase
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olivine
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rock-forming silicate mineral in the crust and mantle with the general composition (Mg,Fe)2SiO4
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orthopyroxene
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rock-forming silicate mineral in the crust and mantle with the general composition (Mg,Fe)SiO3
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peridotite
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a crystalline rock consisting dominantly of olivine and pyroxenes. the principal rock type present in the earth's upper mantle.
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plagioclase
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rock-forming silicate of crust
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primary magma
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a liquid produced by partial melting of a source region and unmodified by any postsegregation process.
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solidus
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the temperature below which magma is completely crystallized, or at which a solid begins to melt
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spinel
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rock-forming oxide mineral found in the crust and mantle.
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batholith
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a vast collection of solidified magmatic bodies (plutons) commonly forming a mountain range like the sierra nevadas
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capture front
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the position of a solidification front denoting a region inward of which crystals are able to move freely relative to one another and outward of which crystals move in concert with their neighbors
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critical crystallinity
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the point in a solidification front where the packing of crystals is close enough to allow formation of a crystalline network
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dike
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a discordant sheetlike body of magma, commonly near vertical, cutting the country rock
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dilatancy
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the tendency of an assemblage of particles to expand or dilate during shear deformation
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mush zone
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the region in a solidification front where crystals and solids tend to move altogether even though the solids are not all physically connected
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neck
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the solidified lump of mass of magmatic rock filling a volcanic vent or crater
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pluton
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an isolated solidified parcel of magma found in the earth's crust and thought to represent an extinct magma chamber
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Rayleigh number
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a pure, dimension-free number the magnitude of which indicates the tendency of a layer to undergo sustained thermal convection. the larger this number, the more vigorous the convection
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rigid crust
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the region marking the trailing half of a solidification front where all crystals are interconnected to form a matrix possessing strength
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sill
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a sheetlike concordant magmatic body usually emplaced horizontal in earth's upper crust
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solidification front
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the marginal zone encompassing all active magmatic and volcanic bodies within which most crystallization takes place
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stock
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any cylindrical subterranean solidified magmatic body with no clear connection to a volcanic vent
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suspension zone
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the inward leading region of the solidification front in which small, newly formed crystals are able to move with ease relative to one another
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hypocenter
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the point of initiation of an earthquake in the earth, also called earthquake focus
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kimberlite
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a very low-silica igneous rock rich in volatiles that erupts explosively from sources in the upper mantle. comonly contains mantle zenoliths; occasionally contains diamonds
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newtonian fluid
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a simple fluid in which the velocity gradient is directly proportional to the applied stress; the constant of proportionality is the viscosity
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reaction rim
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outer rim on a crystal of different composition, or different monerals, which has formed by chemical reaction of the crystal with the surrounding magma
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subduction zone volcanoes
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volcanoes that occur along the earth's plate boundaries where one is being subducted or taken down into the earth's interior. magmas erupted are typically rich in volatiles and the eruptions often explosive
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xenolith
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a foreign rock fragment in an igneous rock or magma
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pumice
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a light colored, cellular, and glassy rock, typically less dense than water because of the large fraction of bubbles (vesicles) in the glass
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andesite
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volcanic rock with 53 - 65 %silica content (SiO2) having a viscosity when molten that is typically intermediate to that of baslt and rhyolite
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basalt
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volcanic rock with 44 - 50 % silica content that in conjunction with typically higher flow temperatures results in relatively fluid magma
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brinkman number
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a dimensionless ratio giving the relative importance of the rate of heat production produced by viscous heating to the rate of heat loss by conduction of heat to cooler boundaries
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caldera
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crater or surface depression resulting from collapse of an underlying magma chamber roof during withdrawal of magma
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coextrusion
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process of simultaneously forcing two or more distinct magmas to flow in magmatic plumbing
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conduit
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a pipe-like pathway for the transport of magma that evolves by preferential channeling (a process involving both melting and solidification) of flow within a dike
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contact
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boundary or surface separating hot magma from cooler host rock
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dike
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a vertically oriented, sheetlike magmatic pathway formed by injection of magma into a thin fracture that fills and propagates within the brittle crust of the earth
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exsolution
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the transition of a volatile component from solution in a magma to a gas phase. the formation of a gas phase results in significant driving forces for magma transport
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lava
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molten rock expelled at the earth's surface by volcanic processes
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lithostatic
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change in static pressure with depth or pressure gradient associated with the overburden of crustal rock. lithostatic pressures for a given thickness of crustal rock are approximately 2.5 - 3 times greater than pressures encountered in a layer of water having the same thickness
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magma
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a mantle or crust derived, physically and chemically complex mixture of molten rock, solids (crystals), and gases
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magmastatic
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change in static pressure with depth change in a fracture or reservoir filled with magma. because magma densities are similar to crustal rock densities, lithostatic and mamgastatic densities are also comparable
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phenocryst
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one of the larger, more distinct crystals in a rock with an otherwise fine-grained texture
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reynolds number
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a dimensionless quantity characterizing the relative importance of inertial or momentum related forces to viscous forces in fluid flow. in magma viscous forces usually dominate, resulting in a reynolds number that is much less than 1
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rheology
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the study of the deformation and flow of fluids
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rhyolite
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volcanic rock with more than 68% silica having exceptionally sluggish flow characteristics owing to its high silica content and typically lower emplacement temperatures
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seismicity
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the detectable seismic activity that is here associated with the transport of magma
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silicic
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having or being characterized by a high silica content
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subliquidus
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state of magma in which crystalline solids exist in an otherwise liquid regime. the state is associated with higher viscosities than magmas that are purely liquid
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thermal diffusivity
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a quantity characterizing the ability of a material to allow heat to be transported by conduction (thermal diffusion) alone. the diffusivity is the ratio of the thermal conductivity to the product of the material density and the specific heat
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viscosity
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the resistance of a fluid to flowing in response to applied pressure forces. the higher the viscosity, the more resistant the fluid to flow
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volatiles
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a compound that can exist as a gas at magmatic temperatures and pressures characteristic of the shallow crust. the exsolution of volatiles results in the existence of a gas phase that is important for driving the transport of magma
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xenolith
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a piece of mantle or crustal rock picked up by flowing magma
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annular flow
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one of four two-phase flow regimes, in which magma lines the conduit walls and gas flows in a central jet.
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bubbly flow
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flow regime in which the gas phase appears as bubbles suspended in a continuous magma phase
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degassing
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the process by which magma loses its dissolved volatile species as pressure decreases.
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dispersed flow
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flow regime in which magma takes the form of fragments in a continuous gas phase.
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fragmentation
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process by which bubbly magma breaks up, generating magma fragments and a continuous gas phase.
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laminar flow
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flow regime where viscous effects dominate and flow trajectories are parallel to conduit walls.
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reynolds number
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dimensionless parameter that defines the relative importance of viscous and inertial forces during flow.
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slug flow
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flow regime in which large gas pockets, which are almost as large as the eruptive conduit, rise through magma.
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turbulent flow
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flow regime where inertial effects dominate, such that the flow is well mixed by small-scale eddies.
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volatiles
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chemical species or compounds that are dissolved in natural magmas at high pressure and that appear as low-density gas at low pressures. the most common are water and carbon dioxide.
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destructiveness index
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the logarithm of the area covered by lava, pyroclastic flows, and surges, or buried under more than 100kg/m2 of tephra during an eruption.
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intensity
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the mass eruption rate (kg/s). the intensity scale is based on the logarithm of the mass eruption rate.
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magnitude
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the mass of material ejected during a volcanic eruption. the magnitude scale is based on the logarithm of the erupted mass.
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volcanic explosivity index (VEI)
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a widely used classification scheme to describe the size of explosive eruptions. based principally on the erupted mass or volume of a deposit.
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central volcano
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a volcano that erupts magmas of various compositions, for example, basalt and rhyolite. these volcanoes frequently have calderas in their central parts.
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decollement
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a detached structure resulting in differential movement of rock above and below.
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lava shield volcano
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a low-angle volcano constructed principally of basalt lava flows.
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monogenetic volcano
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a volcano that erupts only once
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polygenetic volcano
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a volcano that erupts repeatedly, often in an episodic manner.
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stratovolcano
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a volcano constructed of alternating layers of lava flows and pyroclastic rocks. steeper than shield volcanoes.
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aa lava
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lava flows with extremely irregular surfaces, usually covered by fragments of broken crust that are typically decimeters thick. Thickness of surface crust is controlled by cooling.
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blocky lava
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lava flows with fractured surfaces, usually covered by debris up to meters across. the size of the surface fragments is controlled by the rheology of the lava interior, rather than by the thinner surface crust.
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crust
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the outer part of a lava flow that has solidified after losing heat to the exterior.
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flow
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a discrete body of lava emplaced as a dynamically continuous unit
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flow field
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a collection of lava flows produced by the same effusion.
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lava
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molten or partially molten rock erupted at a planets surface
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pahoehoe lava
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lava flows with smooth, continuous surfaces.
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bubble
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a pocket of gas in a melt
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fragmentation
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the transition from a continuous melt with a dispersed gas phase to disconnected parcels of bubbly melt with a continuous gas phase.
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magma
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silicate melt with dissolved gases; may also contain crystals and/or bubbles.
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pyroclasts
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all solid fragments ejected from volcanoes (from Greek meaning "fire broken")
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pumice
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solidified fragments of quenched vesicular silicic melt
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scoria
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basaltic pumice
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tephra
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all pyroclasts that fall to the ground from eruption columns
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vesicle
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a hole (bubble remnant) preserved in a solidified pyroclast.
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vesicularity
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the volume percent of bubbles in a melt or vesicles in pumice
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vesiculation
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nucleation and growth of gas bubble in a magma.
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annular flow
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two-phase flow (gas and liquid) in a tube. central gas jet surrounded by an annulus of magma. volcanic equivalent: Hawaiian fire fountains.
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gas-piston activity
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a rhythmic rise and fall of the magma level within a volcanic conduit due to ascent and escape of large pockets of magmatic gas.
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Hawaiian eruptions
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basaltic eruptions with very low viscosity magma (10-100 Pa s). Fire fountains and lava flows.
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lava fountain
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a pillar-like jet of gas and molten pyroclasts that towers tens to hundreds of meters above a central vent.
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lava pond
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an accumulation of coalesced molten pyroclasts that are trapped at the vent by the walls of a developing spatter or cinder cone.
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pyroclast
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a general term for any fragment of lava ejected during an explosive volcanic eruption.
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reticulite
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a delicate scoria containing 95 - 99 % void space within a honeycomb-like network of thin glass struts.
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scoria
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a porous, glassy pyroclast containing 70-85% void space.
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slug flow
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two-phase flow in a tube. large gas pocket rising in a liquid and filling up the entire conduit width. characteristic of strombolian explosions and gas-piston events during Hawaiian eruptions.
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spatter bombs
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a glassy pyroclast >64mm across that develops a fluidal shape by the force of ejection.
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strombolian eruptions
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basaltic eruptions with a low viscosity magma (100-1000Pas). series of explosions.
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tremor
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a continuous vibration of the ground around active volcanoes.
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andesite
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The second most abundant rock type, containing mainly phenocrysts of zoned plagioclase, pyroxene, or hornblende and a glassy or fine-grained groundmass.
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blocks/bombs
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Blocks and bombs are fragments of solid rock and semimolten lava, respectively, with diameters > 64mm
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explosive earthquakes
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Isolated, large amplitude earthquakes lasting 10-20s with peak frequencies between 1 and 5 Hz.
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Juvenile Clasts
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Fragments of solidified magma involved with the eruption.
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Lava Dome
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Solidified lava, roughly circular in plan view with small surface area that occupies the vent.
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Shock Waves
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A pressure wave that travels at a velocity greater than the speed of sound of the medium through which it propagates.
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Intensity
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A measure of the rate at which magma is discharged during an eruption.
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Magnitude
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The total mass of material ejected during an eruption.
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VEI
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Volcanic Explosivity Index
A measure of the size of an eruption, mainly based on magnitude, intensity, and destruction power of an eruption. VEI is an eight point scale. |
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Accretionary Lapilli
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Aggregates of fine ash, commonly having a concentric structure and formed by accretion of damp ash in eruption clouds.
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Armoured Lapilli
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Lapilli coated with one or more complete or partial layers of accreted fine ash; essentially a variant of accretionary lapilli.
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cock's tail jets
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The common type of tephra jet, with an arching, multifingered form likened to the shape of a rooster's tail.
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Continuous Uprush
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Sustained phreatomagmatic eruption column that is fed by ongoing or closely spaced explosions.
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Frittering
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Erosion of particles from a vent wall by rushing gases.
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Psuedo-Ballistic Lapilli
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Lapilli deposited individually by fall from a plume that form impact sags similar to those from true ballistics transported by momentum.
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Spall Dome
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Subhemispherical gas-driven shock zone expanding outward from a subaqueous explosion.
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Tachylite and Sidermelane
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Basaltic glass. Sidemalane is translucent; tachylite is cryptocrystalline and opaque as a result of microlite crystallization and is inferred to result from slightly slower chilling.
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Tephra Jets
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Discrete ejections containing tephra and steam driven by steam expansion and momentum of large clasts.
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Vesiculated Tuff
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Tuff containing open, fluid-form spaces among the fragments reflecting entrapment of air in wet, fine-grained ash.
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Ash Aggregation
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Process leading to the formation of clusters of ash particles during transport in an eruption plume.
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Dispersal Index (D)
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A measure of the area covered by a pyroclastic fall deposit, specifically the area enclosed by an isopach drawn at 1/100 of the maximum thickness of the deposit. Phreatoplinian deposits have D values greater than 50km^2.
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External Water
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Any water phase during explosive volcanism that was not originally dissolved in the magma such as surface and groundwater.
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Fragmentation Index (F)
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A parameter measuring the grain size of a pyroclastic fall deposit, specifically the percentage of ash finer than 1mm at the point on the dispersal axis corresponding to 1/10 of the maximum thickness of the deposit. Phreatoplinian deposits typically have F greater than 80%.
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Mud Lump/Mud Pellet
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Ash aggregates of irregular shape and with no discernible concentric internal structure.
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Mud Rain
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Fall-out of ash-bearing droplets of water and dissolved gas species from an eruption plume.
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Phreatoplinian Deposits
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Widespread phreatomagmatic fall deposits.
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Advection
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Horizontal transport of material.
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Chaotic Advection
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The stretching of air parcels into complex shapes by wind.
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Co-Ignimbrite Plume
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Plume produced from a pyroclastic flow.
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Elutriation
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Loss of small particles by the upward flow of gas through a pyroclastic flow.
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Entrainment
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The process of picking up and carrying along.
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Hemispheric Flow
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The largest scale of atmospheric flow, generally in distinct latitudinal bands, also called zonal flow.
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Latent Heat of Condensation
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Heat released upon conversion of vapor to liquid.
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Neutral Buoyancy Level
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Height at which plume density is equal to the surrounding atmosphere.
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Stratosphere
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The upper portion of the atmosphere from an altitude of ~ 10 to 50 km.
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Thermal
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A discrete mass of air or particles and gases that rise in the atmosphere by buoyancy.
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Troposphere
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The lower portion of the atmosphere from ground level to about 10km.
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Tropopause
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Boundary between the troposphere and the stratosphere.
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Turbulent Diffusion
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Mixing by turbulent flow.
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Deposition System
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The entity that deposits pyroclasts and forms pyrocastic deposits. This term is used to emphasize the controls on the manner in which particles come to rest.
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Particle Cohesion
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The sticking together of particles due to either the presence of water (at low temperatures) or to particle plasticity (at high temperatures).
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Particle Trajectory
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The path taken by a moving particle.
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Pyroclastic Density Current
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A gravity-controlled, laterally moving mixture of pyroclasts and gas.
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Pyroclastic Fall
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The rain out of clasts through the atmosphere from an eruption jet or plume during an explosive eruption.
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Pyroclatic Flow
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A pyroclastic density current where most of the material and momentum is contained in a basal concentrated particulate dispersion.
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Pyroclastic Surge
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A PDC where the material and momentum are widely distributed through a deep, dilute, highly turbulent particulate suspension.
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Solids Concentration
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The volume concentration of particles in a transporting or depositing medium, ranging from low (discrete particles) to high (dense-packed assemblage of particles).
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Transport System
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The entity that carries pyroclasts from vent to deposition system. Term used to emphasize the process responsible for transport.
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isopach
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Line joining points of equal thickness in a deposit.
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Isopleth
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Lines joining points where the sizes of the largest clasts are the same.
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Thickness half-distance (bt)
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The "average" distance over which the thickness of a pyroclastic deposit halves.
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Grain size half-distance
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The "average" distance over which the maximum clast size in a deposit halves.
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Base Surge
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A turbulent density current that flows outward from the base of a partially collapsing vertical eruption column derived from a hydrovolcanic (phreatomagmatic) eruption; a type of pyroclastic surge.
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Bedform
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The surface configuration of groups of strata having geometric shapes that repeatedly occur in nature such as ripples, dunes, and plane beds.
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Bedset
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A sequence of beds with distinct internal structures, textures, colors or compositions that set them apart from other sequences, usually bounded by unconformities, or by fallout layers.
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Blast
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A sudden, violent, overpressured explosion projected lateraly or vertically.
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Blocking
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Deflection of the lower, denser portion of a PDC by a topographic barrier while the low density upper parts continue to travel over the barrier.
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Flow Regime
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Hydraulic conditions of noncohesive flow of sand and silt that develop ripples, dunes, plane parallel beds, and antidunes. Progressive changes in bedforms occur as flow regime increases. Low flow regime conditions form small scale ripples that progress to dunes; high flow regime conditions form plane beds and then antidunes.
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Flow Transformation
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Reversible changes (in sediment gravity flows) between turbulent and steady flow related chiefly to particle concentration, thickness of flow, and flow velocity.
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Hydrovolcanic
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All volcanic activity resulting from the interaction between meteoric or connate water and lava, magmatic heat, or gases at or near the surface of the earth. Also phreatomagmatic.
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Pyroclastic Surge
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Low concentration, turbulent PDCs.
Wet surges have temperatures less than 100 deg C where steam condenses and the surge is a three-phase system with water droplets, solid particles, and gas. Dry surges have mean temperatures greater tahn 100 deg C and form by 1) hydrovolcanic eruptions with low water/magma ratio, or 2) by magmatic eruptions that are driven solely by volatiles. |
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Transport and Deposition system.
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The transport system carries particles from the source to the area of sedimentation.
The depositional system deposits particles and includes local movement of particles, such as movement of a mass of particles down a steep slope, after being carried to a particular location by the transport system. |
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Ash flow deposit/ Ash flow tuff
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Deposit of pyroclastic density current(s) consisting predominantly (>50wt%) of ash-size material. In practice, ash flow tuff is used for moderate to large volume ignimbrite in U.S. literature.
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Block-and-ash flow deposit
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Small volume pyroclastic flow deposit characterized by a large fraction of dense to moderately vesicular juvenile blocks in a medium to coarse ash matrix of the same composition.
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Ignimbrite
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Welded or unwelded, pumiceous, ash-rich deposit of pyroclastic density current(s). Formerly used only for strongly welded deposits.
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Pyroclastic Density Current
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A particulate gaseous volcanic flow moving along the ground. Includes both flows and surges.
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Pyroclastic flow deposit
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Predominantly massive, poorly sorted, ash-rich deposit laid down by a particulate gaseous flow.
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Pyroclastic Surge deposit
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Strongly bedded (laminated, low-angle cross bedded) deposits laid down by fast moving gaseous flows of low particle concentration.
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Bulking
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The erosion and incorporation of secondary, exotic debris by lahars as they move downstream.
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Debris Avalanche
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A flowing mixture of debris, rock, and moisture that moves downslope under the influence of gravity. Debris avalanches differ from debris flows in that they are not water saturated and the load is supported entirely by particle-particle interactions.
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Debris Flow
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A water-saturated mixture of debris and water having large sediment concentration that moves downslope under the influence of gravity. Forces related to both solid and fluid phases act together to drive debris flows and determine their distinctive behavior. A fairly uniform mixture of solid and liquid phases in vertical profiles characterizes debris flows and distinguishes them from more water-rich hyperconcentrated flows.
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Debulking
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A process in which the lahar selectively deposits certain particles, owing to size or density, as it moves downstream.
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Granular Temperature
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A measure of degree of particle agitation. May be interpreted as twice the kinetic energy per unit mass of granular solids.
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Hyperconcentrated flow
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A gravitationally driven, nonuniform mixture of debris and water having a water content greater than that of debris flow but less than that of muddy streamflow. Some variation with depth of solids fraction characterizes hyperconcentrated flows and distinguishes their behavior from that of debris flows.
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Lahar
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An Indonesian term that most commonly means debris, transitional, or hyperconcentrated flow originating at a volcano.
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Muddy Streamflow
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A flow that essentially transports sediment as normal streams do, with fine-grained sediment in suspension and coarse-grained sediment moving piecemeal along the bed as bedload.
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Amphitheater
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An arm-chair shaped landscape formed at the source of a sector collapse.
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Debris Avalanche
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The product of a large-scale sector collapse.
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Hummocks
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Characteristic topographic features for debris avalanche deposits. Shape is variable and irregular.
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Jigsaw Cracks
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Characteristic joint patterns within a debris-avalanche block. Typically more irregular than cooling joints.
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Sector Collapse
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A destructive volcanic process during the growth history of a volcano.
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Marginal Basin
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Basin located in the backarc area of an island arc that forms by either extension or capture of a piece of oceanic crust.
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Turbidites
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Deposits produced by sedimentation of particles from a turbidity current.
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Turbidity Current
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Mixture of particles and water that moves in a turbulent fashion downslope under the influence of gravity.
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Volcaniclastics
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Particles formed by the fragmentation of volcanic rocks, irrespective of the method of fragmentation or the nature of the transporting agent.
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Volcaniclastic Apron
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Wedge-shaped accumulation of volcaniclastic material in the backarc area of an island arc.
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Ignimbrite
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Pyroclastic flow deposit.
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Intrusion
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A subsurface igneous rock body formed when molten igneous rock forces its way into surrounding host rocks and then cools.
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Magma Chamber
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An underground reservoir in the Earth's crust filled with magma, from which volcanic materials are erupted.
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Welded Tuff
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A hard pyroclastic rock compacted by internal heat and the pressure of the overlying deposits. Forms the interiors of thick ignimbrite sheets.
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Pyroclastic Flow
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Laterally transported, fluidized mass of hot dry rock fragments mixed with hot gases. Moves away from a volcano at high speeds.
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Composite Volcano
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Relatively large, long-lived constructional volcanic edifice, comprising lava and volcaniclastic products erupted from one or more vents, and their recycled equivalents.
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Compound Volcano
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Volcanic massif formed from coalesced products of multiple, closely spaced vents.
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Debris Avalanche
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Catastrophic landsliding of gravitationally unstable volcano flanks resulting in a widely dispersed deposit at the foot of the edifice, typically characterized by a hummocky surface.
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Edifice
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Constructional volcanic mass.
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Ring Plain
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Region surrounding a volcano beyond lower topographic flanks over which tephra and mass wasting products are radially distributed.
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Satellite Vents
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Small monogenetic volcanic features distributed over the flank of a larger composite edifice.
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Steady-State or Equilibrium Edfiice Profile
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Shape of the edifice once an active volcano has become well established-follows the initial cone building, precedes long-term erosional degradation, and represents a balance between construction through mass addition (eruption) and degradation through erosion.
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Topographic Inversion
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Process whereby through time valleys become ridges and vice versa. Can occur on volcanoes as volcanogenic products such as lavas are channeled down valleys, focusing subsequent erosion along their edges.
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Vent
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Surface opening at which volcanogenic material is erupted.
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Accretionary Lapilli
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Tightly bound, approximately spherical aggregates of ash particles. They form in eruption clouds, by raindrops falling through the eruption cloud and by electrostatic attraction.
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Diatremes
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Funnel-shaped breccia pipes that reach as much as 2500m in length. Thought to form by hydrovolcanic fragmentation and wall rock collapse. MAy underlie maars and grade at depth into dikes.
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Strombolian eruptions
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Discrete explosions at periodic intervals of a few seconds to minutes or hours.
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Surtseyan Eruptions
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Hydrovolcanic explosions dominated by jets of wet tephra. Result in tuff cones. Used mostly for volcanoes erupting through seawater.
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What is Brinkman number a measure of?
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Brinkman number is a measure of the rate of viscous heat production to the rate of conductive heat loss.
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