What Does The Amount Of Silica In A Volcanoâ€™s Magma Determine About Its Eruption??
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.
What does the amount of silica in a volcano’s magma determine about its eruption 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 affect the viscosity of magma?
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 silica content of the magma affect the VEI of an eruption?
Magmas that have a high silica content will therefore exhibit greater degrees of polymerization and have higher viscosities than those with low-silica contents. The amount of dissolved gases in the magma can also affect it’s viscosity but in a more ambiguous way than temperature and silica content.
Why does silica make magma more explosive?
Magmas with higher silica concentration are more viscous and thus move slower than magmas with less silica. … More crystals in the magma enable more gas bubbles to form and so they make an eruption more explosive.
What is the connection between the amount of silica in a melt and how viscous it is?
What is the connection between the amount of silica in a melt and how viscous it is? Silica forms strong bonds so higher amounts of silica make for more viscous magma.
What happens as the relative amount of silica in a magma or lava increases?
–Partial melting and incorporation of crustal rocks increase silica content to intermediate or felsic range. -Result is a viscous (sticky) magma that contain lots of volatiles that want to escape quickly – this tends to produce violent eruptions.
What does it mean by higher silica content magma in terms of viscosity?
The higher the amount of silica in the magma the higher is its viscosity. Viscosity is a liquid’s resistance to flow. Viscosity determines what the magma will do. Mafic magma is not viscous and will flow easily to the surface. Felsic magma is viscous and does not flow easily.
What is a silica content?
Of the various glass families of commercial interest most are based on silica or silicon dioxide (SiO2) …… traditional ceramics: Silica and feldspar. Other constituents of traditional ceramics are silica and feldspar. Silica is a major ingredient in refractories…… refractory: Silica.
Why does silica increase viscosity?
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. The more mafic the lava (the less silica in it) the lower the viscosity.
How does the amount of silica affect eruptions?
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 amount of silica affect the color of igneous rock?
The more silica you have in a rock the paler it tends to be. Felsic rocks have high silica content because they contain lots of quartz and another mineral called feldspar.
How much silica is in lava?
Felsic or silicic lavas have a silica content greater than 63%.
How does silica get into magma?
Silicate-rich magmas are typically formed at destructive plate boundaries by partial melting and/or assimilation of crustal rocks (which are richer in silica than the rock of the mantle).
What is silica in magma?
Silicon dioxide the most abundant rock-forming compound on Earth and the predominant molecular constituent of volcanic rocks and magmas. It tends to polymerize into molecular chains increasing the viscosity of the magma.
Which magma has the highest silica content?
As a result of its higher viscosity and gas content intermediate magma builds up pressure below the Earth’s surface before it can be released as lava. Felsic magma has the highest silica content of all magma types between 65-70%. Thick viscous felsic magma can trap gas bubbles in a volcano’s magma chamber.
What are the differences between pahoehoe and AA?
Pahoehoe is lava that in solidified form is characterized by a smooth billowy or ropy surface while aa is lava that has a rough jagged spiny and generally clinkery surface. In thick aa flows the rubbly surface of loose clinkers and blocks hides a massive relatively dense interior.
What is the silica content in a magma that has low viscosity?
BASALTIC magmas have a LOW SILICA content (45-55%) and referred to as MAFIC in composition. RHYOLITIC magma contains more than 65% SILICA and is referred to as FELSIC.
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 happens if a volcanoes magma is high in silica?
Lava with high silica content is thick and viscous and does not readily flow. Lava rises up toward the surface but is too thick to squeeze through the cracks and fissures in the Earth. As lava continues to rise upward pressure continues to build.
What elements has the highest amount in the magma?
Oxygen the most abundant element in magma comprises a little less than half the total followed by silicon at just over one-quarter. The remaining elements make up the other one-quarter. Magmas derived from crustal material are dominated by oxygen silicon aluminum sodium and potassium.
How does magma change during crystallization?
Magma is a mixture of liquid rock crystals and gas. If magma makes it to the surface it will erupt and later crystallize to form an extrusive or volcanic rock. If it crystallizes before it reaches the surface it will form an igneous rock at depth called a plutonic or intrusive igneous rock.
Has the highest amount of silica while Brainly?
While the felsic rock has the highest amount of silica i.e 65 percent of silica.
Which type of magma has the highest silica content and viscosity the least silica content and viscosity?
How do silica and temperature affect the viscosity of magma?
Explanation: Viscosity of magma the resistance to flow depends on composition of the magma and temperature. Higher silica content means higher viscosity. … Hence lower viscosity and low gas content mean higher temperature of magma.
What does magma with high silica content form?
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. All magma that reaches the surface can be classified as Lava.
What is one factor that determines how explosive a volcanic eruption?
The amount of water vapor and other gases present is one factor that determines whether a volcanic eruption will be quiet or explosive.
What would a nonexplosive eruption look like?
Non-explosive type eruptions mostly produce various types of lava such as a‘a pāhoehoe and pillow lavas. Some signs that a volcano may soon erupt include earthquakes surface bulging gases emitted as well as other changes that can be monitored by scientists.
How magma composition affects the eruption of a volcano?
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 type of eruption is the most explosive?
What kind of magma produces violent eruptions?
Explosive eruptions are favored by high gas content & high viscosity magmas (andesitic to rhyolitic magmas). The explosive bursting of bubbles fragments the magma into clots of liquid that cool as they fall through the air.
How does the silica content in magma affect the formation of surface landforms?
It is the silica content that controls the viscosity of the magma and hence the nature of the volcanism that is seen. The low levels of silica mean that Hawaiian magma has a low viscosity which explains why we see lava readily cascading downslope and being churned up in the air in great fire fountains.
Why do some volcanoes have more silica?
Volcanoes that form along convergent plate boundaries have more silica because the lavas become contaminated with sediment and often with high-silica continental crust as they move upward toward the surface.
What characteristics of magma determines its explosiveness?
Viscosity together with the amount of gas dissolved in magma can determine the explosivity of the eruption. More viscous magma with volatiles is more explosive than less viscous magma where gases can bubble out relatively easily.
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