-why is a volcano that is fed by highly viscous magma likely to be a greater threat to life and property than a volcano supplied with a very fluid magma?
-A volcano that is fed by highly viscous magma is likely to be a greater threat to life and property than a volcano supplied with a very fluid magma.
-The viscosity of the magma feeding a volcano affects how explosive the eruption will be.
-A high viscosity magma will cause the molten rock to be more sluggish as it moves up to the surface, resulting in larger and more powerful explosions.
Magma that is more liquid-like and less viscous is often hotter and contains less volatile material than magma that is more viscous. The most significant difference is that the more viscous magma has a much higher mechanical strength to resist the movement and expansion of air bubbles, which in turn limits volatiles, promotes excess pressure build-up in the magma chamber, and increases the likelihood of an explosive event occurring. There is less of a chance of an explosion occurring when liquid magma is present because air bubbles have more room to grow, ascend, and escape from the magma chamber.
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-What characteristics are shared by volcanoes that are known for their very powerful eruptions? A. Their magma has an exceptionally high proportion of silicic acid. B. They are a kind of volcano known as a shield. C. The lava in these volcanoes has a low viscosity. They do not have any magma, but they do have a lot of lava.
-Why do shield volcanoes only have moderately active eruptive periods? A. The magma they produce has a large proportion of silicic acid. B. They create calderas in the process. C. The magma inside of them has an exceptionally low viscosity. They contain an abundance of magma. D.
-Which of the following conditions of the magma within a volcano is most likely to result in an explosive and devastating eruption? Pick only one: a. magma that is thick and has a high concentration of gases; b. magma that is thin and contains a low concentration of gases c. a mountainous volcanic region with thin magma and a high height
-There is no correlation between the ___ and the violentness or calmness of a volcano’s eruption. magma’s makeup the temperature of the magma, the height of the volcano‘s cone, and the amount of dissolved gases present in the magma are all important factors.
-Give an example of each of the following three elements that influence the character of a volcanic eruption: Which part does each play in the whole?
Temperature: the higher the temperature, the less viscous the magma will be composition: a lower percentage of silica results in a lower viscosity.
dissolved gases: higher viscosity equals greater volume of gas
-Why is it that a volcano that is supplied with extremely viscous magma is more likely to pose a larger risk to human life and property than a volcano that is supplied with very fluid magma?
Because gas is trapped more in highly viscous magma, the gas will build up and eventually explode, whereas with fluid magma the gas can escape, allowing the magma to simply flow out of the volcano. This makes a volcano that is fed by highly viscous magma more likely to be a threat to life and property than a volcano that is supplied with very fluid magma.
Provide an explanation of the pahoehoe and aa lava flows.
Pahoehoe has a texture that is similar to that of twisted rope.
Aa: a texture that is choppy, jagged, and blocky
1. hazardous 2. develop in areas where convergent borders meet
3. a high degree of viscosity
4. a high gas level
The Cinder Volcano is the smallest and only erupts once in a single, brief eruption.
1. the greatest in size 2. the least hazardous 3. contains pahoehoe as well as aa lava flow
4. a low degree of viscosity
5. low gas
6. mafic composition
7. happens in areas with high temperature
Describe a lahar
A lahar is a kind of fluid mudflow that is made up of mud, lava, and debris that flows down the slopes of volcanoes.
Provide an example of a well-known volcano for each of the three different categories of volcanoes.
Composite: Mount St. Helens
Cinder: Sunset Crater (AZ)
Hawaii acts as a shield.
What kind of effects does the thickness of the magma that is fed into volcanoes have on the people and property that are nearby? Because it is more explosive and, as a result, more difficult or impossible to anticipate, a volcano that erupts very viscous lava poses a higher risk to human life and property than other types of volcanoes.
However, the viscosity of the magma is another crucial aspect that plays a role in predicting whether or not an eruption would be explosive. If the magma has a low viscosity, as basalt does, then the gases that are trying to escape will be able to move through the magma quickly and get to the top.
When magmas with lower temperatures and higher viscosities (such andesite), which are closer to the surface, they may cause explosive eruptions. Because dissolved gases are unable to leave as readily, pressure may build up, which can eventually lead to gas explosions that launch shards of rock and lava into the air. Because lava flows are far more viscous and adherent, they do not move as readily downward.
When lava is dense and sticky, it makes it difficult for gases to escape. The pressure rises to the point when the gases forcefully escape and then explode.
– The viscosity of a magma is an important factor to consider when assessing the potential for a volcanic eruption to cause damage. A volcano fed by highly viscous magma is likely to be a greater threat to life and property than a volcano supplied with a very fluid magma, due to the increased likelihood of pyroclastic flows and other dangerous phenomena. It is therefore important for scientists and authorities to be able to accurately assess the viscosity of magma in order to predict eruptions and protect people and property.