What Controls The Viscosity Of Lava?
A magma’s viscosity is largely controlled by its temperature composition and gas content (see downloadable programs at the bottom of this page). The effect of temperature on viscosity is intuitive. Like most liquids the higher the temperature the more fluid a substance becomes thus lowering its viscosity.
What element affects the viscosity of lava?
Temperature: The hotter the lava the lower the viscosity (the thinner it is). The cooler the lava the higher the viscosity (the thicker it is). Composition: he more felsic the lava (the more silica in the lava) the higher the viscosity because silica forms chains in the cooling lava even before it crystallizes.
What determines the viscosity of lava quizlet?
–Lava – molten rock at the surface. -Viscosity depends upon temperature & magma composition (most important).
What increases the viscosity of magma?
The viscosity of magma increases with: high % silica and cooler temperatures. … Plutonic rocks are formed when magma cools deep in the crust without erupting. Magma that is very thick (viscous) is more likely to remain below the surface.
Why does viscosity of lava vary between volcanoes?
Magmas that are more rhyolitic have a higher gas content. This gas content and relative viscosity leads to the more explosive and violent eruptions that occur at composite volcanoes. In general SiO2 content controls the relative viscosity of a magma. Viscosity is the ability of a liquid to resist flowing.
What are the three major factors controlling the viscosity of magma lava?
The three factors that influence the viscosity of a lava are temperature the dissolved gases it contains and its chemical composition.
What are the three factors that affect the viscosity of magma?
A magma’s viscosity is largely controlled by its temperature composition and gas content (see downloadable programs at the bottom of this page). The effect of temperature on viscosity is intuitive. Like most liquids the higher the temperature the more fluid a substance becomes thus lowering its viscosity.
What activates viscous magma?
Three factors that affect magma viscosity are temperature composition and presence of dissolved gases.
What does magma viscosity depend on?
Viscosity is the resistance to flow (opposite of fluidity). Viscosity depends on primarily on the composition of the magma and temperature. Higher SiO2 (silica) content magmas have higher viscosity than lower SiO2 content magmas (viscosity increases with increasing SiO2 concentration in the magma).
How does the viscosity of magma affect the style of eruption?
A more viscous (thick) magma will produce a more violent eruption This is controlled in part by the concentration of silica in the magma. A magma with low silica (<45%) will be runny and so the eruption will not be explosive. A magma with high silica (>60%) will be quite viscous and so the eruption will be violent.
What factors control the viscosity of a melt?
Answer: Viscosity in a melt is controlled by its composition (specifically silica content) and temperature. Temperature affects viscosity because heat causes chemical bonds to break more easily. Therefore a hotter lava of a given composition is less viscous than a Page 2 cooler lava of the same composition.
What causes lava to be fluid and runny?
Magma’s viscosity is determined by its silica content. What causes lava to be fluid and runny? … Lava with low silica content is fluid and runny. Lava with high silica content erupts as pyro clasts.
What is viscosity of lava?
What two factors control the explosiveness of an eruption?
The amount of water vapor and other gases present is one factor that determines whether a volcanic eruption will be quiet or explosive.
How does the viscosity of lava affect the formation of rocks?
Why does low viscosity lava produce gentle eruptions?
If a magma has low viscosity (it is runny) gas can escape easily so when the magma erupts at the surface it forms lava flows. These eruptions are (relatively!) gentle effusive eruptions.
What two principal factors affect the viscosity of magma lava?
The viscosity of magma depends upon its silica content and temperature.
What are the factors that affect viscosity?
Viscosity is resistance to flow. For liquids typically the larger the intermolecular forces (IMF) the higher the viscosity. The other factors that affect viscosity are temperature and the shape of the molecule.
What are the four factors that determine the composition of magma?
the formation of magma are temperature pressure water content and mineral content.
What methods are used to control lava flows?
The methods that have been attempted to control lava flows are hydraulic chilling and wall construction. Differentiate between ash falls lateral blasts and pyroclastic flows.
Which one does not affect lava viscosity?
Question: Which of the following does not affect the viscosity of magma? Temperature Silica Content Amount of gas None of these affects the viscosity of the magma.
What are the two main determinants of viscosity in lavas?
The viscosity of a magma is affected by its silica content and temperature. The amount of silica influences the magma’s viscosity in such a way that if the silica content is low the magma would have low viscosity whereas a high content of silica would make the magma more thick and sticky.
How does water affect lava viscosity?
When magmas migrate from their source up towards the Earth surface water exsolution can result in large (up to several orders of magnitude) increases in magma viscosity because of the strong effect of water on the viscosity of silicate melts (Leonteva 1940 Saucier 1952 Friedman et al.
Does water make lava more viscous?
Although lava can be up to 100 000 times more viscous than water with a viscosity roughly similar to ketchup lava can flow great distances before cooling and solidifying because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava helping keep it hot and inviscid enough to …
What causes magma to move?
The high temperatures (900°C) and extremely high pressures that occur in the mantle layer of the Earth are enough to melt rock. The high pressure changes the rock into a viscous semisolid called magma. … This semisolid magma continues to move upwards through the crust experiences less pressure and so becomes more fluid.
What makes magma different from lava?
How does viscosity of lava determine the shape of volcanoes?
The low viscosity of the magma allows the lava to travel down slope on a gentle slope but as it cools and its viscosity increases its thickness builds up on the lower slopes giving a somewhat steeper lower slope. Most shield volcanoes have a roughly circular or oval shape in map view.
Magmas differ in composition which affects viscosity. Magma composition has a large effect on how a volcano erupts. Felsic lavas are more viscous and erupt explosively or do not erupt. Mafic lavas are less viscous and erupt effusively.
What affects magma composition?
Different minerals within a rock melt at different temperatures. The amount of partial melting and the composition of the original rock determine the composition of the magma. … The higher the amount of silica in the magma the higher is its viscosity. Viscosity is a liquid’s resistance to flow.
What are some key factors that control the cooling time of magma?
What factors control the cooling times of a magma within the crust? The depth of the intrusion the shape and size of a magma body: the greater the surface area for a given volume of intrusion the faster it cools and the presence of circulating ground water: water passing through magma absorbs and carries away heat.
What factors cause melting and thus the formation of magma?
Differences in temperature pressure and structural formations in the mantle and crust cause magma to form in different ways. Decompression melting involves the upward movement of Earth’s mostly-solid mantle. This hot material rises to an area of lower pressure through the process of convection.
How does magma keep its fluid state under Earth’s crust?
What causes explosive volcanic eruptions?
A volcano’s explosiveness depends on the composition of the magma (molten rock) and how readily gas can escape from it. As magma rises and pressure is released gas bubbles (mainly of water vapor and carbon dioxide) form and expand rapidly causing explosions.
What are the differences in the lava and volcanic setting that will control whether the eruption will be explosive or effusive?
Whether a volcano will erupt explosively or effusively is determined by the presence of bubbles. … This volcano erupts explosively. If bubbles formed higher in the conduit the magma would not fragment as much and the volcano would erupt more effusively. Bubbles control a factor known in volcanology as explosivity.
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