How does dissolved gas affect magma?

How does dissolved gas affect magma?

Magma contains dissolved gases, which provide the driving force that causes most volcanic eruptions. As magma rises towards the surface and pressure decreases, gases are released from the liquid portion of the magma (melt) and continue to travel upward and are eventually released into the atmosphere.

What affects the viscosity of a 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 are the 3 factors affecting the viscosity of magma?

The three factors that influence the viscosity of a lava are temperature, the dissolved gases it contains, and its chemical composition.

How does each of the factors affect the viscosity of the magma or lava?

Temperature, composition, and volatile (gas) content largely determine 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).

How does gas content affect viscosity?

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 increases the viscosity of magma?

In other words, as magma cools, its viscosity increases. This property is increased by crystallization of magma while temperature decreases. Finally, the composition of a magma highly affects its viscosity. A higher concentration in silica leads to a more acid/more viscous magma.

Why are the viscosity and gas content of a magma important in determining the type of volcanic rocks that will be formed when that magma is extruded?

At convergent boundaries magma is formed where water from a subducting plate acts as a flux to lower the melting temperature of the adjacent mantle rock. The higher viscosity prevents gases from escaping from the magma, and so felsic magmas are more pressurized and more likely to erupt explosively.

What two principal factors affect the viscosity of magma lava?

The viscosity of magma depends upon its silica content and temperature. How hot are magma and lava?

What is the most important factor that influences the viscosity of magma?

Viscosity describes how thick and sticky the lava is, which influences how fast it flows. The two main factors that affect viscosity are temperature and silica content. Experiements The “Treacle Test” experiment is designed to enable students to investigate how temperature, volatiles and crystals may affect viscosity.

Which does not affect the viscosity of the magma?

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.

How does the viscosity of magma change as magma cools?

How does the viscosity of magma change as magma cools? It increases with decreased temperature. Is the viscosity of magma that is higher or lower than magma that is low in silica? Magma high in silica has higher viscosity.

How is magma composition related to viscosity?

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.

How does the amount of dissolved gases in magma affect its viscosity?

The amount of dissolved gasesin the magma can also affect it’s viscosity, but in a more ambiguous way than temperature and silica content. When gases begin to escape (exsolve) from the magma, the effect of gas bubbles on the bulk viscosity is variable.

How is the volatile content of magma determined?

Volatile Content: Magma invariably contains small amounts of dissolved gas (water, CO2 etc) which is released as pressure is removed. Magmas formed by melting of mantle rocks have generally low volatile contents, but those formed by partial melting of crustal rocks are often volatile-rich.

How does the viscosity of a gas bubble change?

Although the growing gas bubbles will exhibit low viscosity, the viscosity of the residual liquid will increase as gas escapes. The overall bulk viscosity of the bubble-liquid mixture depends on both the size and distribution of the bubbles.

What are the three factors that influence viscosity of a lava?

Temperature, composition, and volatile (gas) content largely determine 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).