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Effusive eruptions occur when hot basalt magmas reach the surface allowing gases to escape easily as the magma erupts. Explosive eruptions occur where cooler, more viscous magmas reach the surface. The gases cannot escape as easily, so pressure builds up until the gasses violently blast out rock and lava.
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What does viscosity have to do with eruptions?
The viscosity of magma or lava will determine whether or not the eruption is explosive or quiet. Higher viscosity magma can result in explosive eruptions. Lower viscosity magmas tend to flow more freely.
How does the viscosity of magma contrast Krakatoa?
The viscosity of magma affects its ability to flow. For Krakatoa, the magma was characterized by high viscosity due to its high silica content, causing pressure buildup leading to explosive volcanic eruptions. The high viscosity of the magma at Krakatoa contributed to the violent nature of its eruptions in 1883.
Is thick and sticky a physical property of magma from an explosive eruption?
Yes, magma viscosity (thickness) and stickiness can be physical properties of magma from explosive eruptions. Higher viscosity and stickiness can lead to explosive eruptions because gas bubbles are trapped in the magma, building up pressure until a violent release occurs.
What two factors control the explosiveness of an eruption?
The explosiveness of an eruption is primarily controlled by the viscosity of the magma and the amount of gas trapped in it. Low viscosity magma with high gas content tends to lead to more explosive eruptions, while high viscosity magma with lower gas content leads to less explosive eruptions.
Why are eruptions of mafic magma rather quiet?
The explosive force of violent eruptions is driven by gas trapped in the magma under pressure. Mafic magma often has a relatively low gas content and so usually erupts in a non-explosive or mildly explosive.
What does viscosity have to do with eruptions?
The viscosity of magma or lava will determine whether or not the eruption is explosive or quiet. Higher viscosity magma can result in explosive eruptions. Lower viscosity magmas tend to flow more freely.
How does the viscosity of magma contrast Krakatoa?
The viscosity of magma affects its ability to flow. For Krakatoa, the magma was characterized by high viscosity due to its high silica content, causing pressure buildup leading to explosive volcanic eruptions. The high viscosity of the magma at Krakatoa contributed to the violent nature of its eruptions in 1883.
Why does granitic magma cause explosive eruptions?
Granitic magma is highly viscous (resists flow). This high viscosity results in the entrapment and buildup of gases which create explosive eruptions.
Compare and contrast the three types of magma?
Basaltic Magma is typically forms when rocks in the upper mantle melt...Andesitic Magma is found along continental margins....Rhyolitic Magma forms when molten material rises and mixes with the overlying silica-and water-richcontinental crust...All 3 of them is a magma.
Is thick and sticky a physical property of magma from an explosive eruption?
Yes, magma viscosity (thickness) and stickiness can be physical properties of magma from explosive eruptions. Higher viscosity and stickiness can lead to explosive eruptions because gas bubbles are trapped in the magma, building up pressure until a violent release occurs.
What two factors control the explosiveness of an eruption?
The explosiveness of an eruption is primarily controlled by the viscosity of the magma and the amount of gas trapped in it. Low viscosity magma with high gas content tends to lead to more explosive eruptions, while high viscosity magma with lower gas content leads to less explosive eruptions.
Why are eruptions of mafic magma rather quiet?
The explosive force of violent eruptions is driven by gas trapped in the magma under pressure. Mafic magma often has a relatively low gas content and so usually erupts in a non-explosive or mildly explosive.
A volcano with a magma supply which is felsic and has a high viscosity will tend to have what type of eruption?
A volcano with felsic magma and high viscosity will likely have explosive eruptions due to the build-up of pressure from gas bubbles being trapped within the thick magma. This can lead to violent eruptions with ash, gas, and volcanic rocks being ejected forcefully from the volcano.
What are the two factors the control whether a volcano eruption will be explosive or quiet?
The two main factors that control whether a volcano eruption will be explosive or quiet are the viscosity of the magma and the presence of dissolved gases. High viscosity magma (thick and sticky) and high gas content tend to result in explosive eruptions, whereas low viscosity magma (thin and runny) and low gas content lead to quiet eruptions.
Why is silica rich magma associated with explosive eruptions?
Silica-rich magma has high viscosity, which can trap gas bubbles. When pressure builds up, the gas can cause explosive eruptions as it tries to escape through the thick magma. The high silica content also promotes the formation of explosive pyroclastic materials during an eruption.
Did Krakatoa have high viscosity lava?
No, Krakatoa is known for its explosive eruptions due to its low-viscosity lava. This type of magma allows gas bubbles to rise quickly to the surface, resulting in powerful and destructive eruptions.
What element has the greatest effect on magma characteristics?
The silica content in magma has the greatest effect on its characteristics. High silica content makes magma more viscous and results in explosive volcanic eruptions, while low silica content produces runny magma and less explosive eruptions.
