How does silica affect viscosity of magma?

The amount of silica in magma helps to determine its viscosity. The more silica magma contains the higher its viscosity. Magma that is high in silica produces light-colored lava that is too sticky to flow very far ex. … Low-silica magma flows readily and produces dark-colored lava ex.

How does silica content affect the viscosity of magma quizlet?

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.

How does silica content relate to viscosity?

Magmas with a higher SiO2 content have a higher viscosity. Ultimately, the viscosity of a magma will determine the shape a volcano takes over continued eruptions. A magma's silica content will not only control the rock type that forms, it also controls the relative viscosity of the magma.

How does silica effect magma?

The silica content of the magma determines how thick the magma is, how easily it flows and how easily dissolved gases within the magma can escape; therefore the silica content determines the characteristic of the volcanic eruption and the shape and size of the resulting volcanic cone.

Why does silica increase viscosity?

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.

Why does silica affect lava flow?

Silica: Influences lava viscosity and overall shape of the volcano. Silica molecules form a strong bond that permits entrapment of volcanic gases and promotes explosive volcanic eruptions. Low-silican magmas allow rapid escape of gases and low-explosivity eruptions.

How does the viscosity of magma directly relate to the amount of silica magma contains?

Viscosity of Magmas 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).

Which factors can cause magma to decrease its viscosity?

Lower temperature magmas have higher viscosity than higher temperature magmas (viscosity decreases with increasing temperature of the magma).

How does temperature and silica content affect the viscosity of magma?

Viscosity of magma, the resistance to flow depends on composition of the magma and temperature. Higher silica content means higher viscosity. But lower temperatures and low gas content mean higher viscosity. Hence, lower viscosity and low gas content mean higher temperature of magma.

What factors 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 affects the viscosity of magma?

Viscosity of Magmas 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).

What is the silica content of magma that has a low viscosity?

~50% CONTROLS ON EXPLOSIVITY

SiO2	MAGMA TYPE	VISCOSITY
~50%	mafic	low
~60%	intermediate	intermediate
~70%	felsic	high

What is a silica content?

The silica content determines how thick the lava is, how easily it flows and how easily dissolved gases can escape; therefore the silica content determines the characteristic of the volcanic eruption and the resulting volcanic cone.

What happened of the magma with high silica content?

Magmas with high silica content have a high viscosity (resistance to flow) and are generally more explosive when eruptions occur. All magmas also contain some degree of trapped gasses (CO2 & H2O ). The more trapped gas the more violent the explosion.

What does magma with high silica content form?

High silica content produces a thick viscous lava that does not flow easily. Low silica content produces a lava that is more fluid and flows more easily. Lava is less dense than the surrounding rock and rises up to the surface through cracks and crevices under the Earth.