Volcano Introduction
Volcano Lava Experiment
On this day, we went to the Discovery Kids website and experimented with two variables of volcanic lava - Gas and Viscosity to see what happens as a result of our changes. Keep in mind that we only changed 1 variable at a time. We soon learned that we created three basic volcanoes: shield, strato and cinder cone.
On the next page (pg. 17), we took that information (dissolved gasses & viscosity) and filled in the descriptions of each volcano and the associated vocabulary terms.
Volcanoes mostly occur at plate boundaries
On the next page (pg. 17), we took that information (dissolved gasses & viscosity) and filled in the descriptions of each volcano and the associated vocabulary terms.
Volcanoes mostly occur at plate boundaries
Different Types of Lava = Different Types of Volcanoes
Different types of Eruptions and Lava Flows
Stratovolcano
Stratovolcanos are generally made of higher viscous magma/lava material (Silica based magma) - which accounts for their steep sides and tall structure. When the magma consists of a high concentration of gasses, these volcanoes generate the most violent types of eruptions - often shooting ash and debris 10's of miles into the atmosphere. Some examples of this are Mt. Pinatubo, Mt. Hood, Mt. St. Helens, Mt. Rainier, Mt. Shasta, and many more.
Strato-Volcano Eruptions
Plinian Eruption
(High Viscosity, High Gas) |
Volcanian Eruption
(Med High Viscosity & High Gas) |
Slow Eruption from a dome collapse that produces a Pyroclastic Flow
(High Viscosity, Low Gas) |
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Shield Volcano
Shield Volcanoes are the largest type of volcano with a very wide base relative to its height. It has a very gentle slope due to the low viscosity of the lava that flows out of the magma chamber. What makes this magma runny is the high iron content and low silica content.
A classic example of a shield volcano are the Hawaiian Islands.
A classic example of a shield volcano are the Hawaiian Islands.
Shield Volcano Eruptions
Hawaiian Fire Fountain
(Low Viscosity, High Gas) |
Effusive Eruption
(Low Viscosity, Low Gas) |
Effusive Eruption - Continued
(Low Viscosity, Low Gas)
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Cinder Cone
The cinder cone is the shortest volcano and the shortest lived volcano. It has steep sides with a small base due to the type of magma that ejects out. The magma that ejects out of this type of volcano is semi sticky - it has a mixture of iron rich and silica rich minerals - so it's sticky and flows at the same time.
Cinder Cone Volcanic Eruptions
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Conclusion
What we notice is the following:
High Viscosity: (Magma / Lava is sticky)
With High Viscosity (sticky magma/lava) you get a stratovolcano like the one pictured below – where you have steep sides, meaning that its base is more narrow relative to its height. The sides are more steep in slope.
High Gas:
With high gasses, you still get the same structure, but the eruption is more violent.
Low Gas:
With low gasses, you still get the same structure, but the eruption is less violent.
With High Viscosity (sticky magma/lava) you get a stratovolcano like the one pictured below – where you have steep sides, meaning that its base is more narrow relative to its height. The sides are more steep in slope.
High Gas:
With high gasses, you still get the same structure, but the eruption is more violent.
Low Gas:
With low gasses, you still get the same structure, but the eruption is less violent.
Low Viscosity: (Magma / Lava is runny)
With runny lava, the lava oozes outward – which makes a wide base relative to its height. The sides are gently sloped, which makes a shield volcano.
High Gas:
With high levels of gas, we still get the same type of volcanic structure, but during the eruption, we get a fire fountain that shoots high in the air; sometimes even 100’s of meters in the air.
Low Gas:
With low levels of gas, we still get the same type of volcanic structure, but during the eruption, we get lava that oozes out and runs down the sides of the volcano.
With runny lava, the lava oozes outward – which makes a wide base relative to its height. The sides are gently sloped, which makes a shield volcano.
High Gas:
With high levels of gas, we still get the same type of volcanic structure, but during the eruption, we get a fire fountain that shoots high in the air; sometimes even 100’s of meters in the air.
Low Gas:
With low levels of gas, we still get the same type of volcanic structure, but during the eruption, we get lava that oozes out and runs down the sides of the volcano.
Medium Viscosity:
With medium viscosity, you get a small cinder cone volcano. The magma is slightly stickier than a shield volcanoes lava, which make the sides a little steeper.
High Gas:
With high levels of gas, lava projectiles coming out of the volcano during an eruption, reach higher heights.
Low Gas:
With low levels of gas, lava projectiles coming out of the volcano during an eruption, do not go very high.
With medium viscosity, you get a small cinder cone volcano. The magma is slightly stickier than a shield volcanoes lava, which make the sides a little steeper.
High Gas:
With high levels of gas, lava projectiles coming out of the volcano during an eruption, reach higher heights.
Low Gas:
With low levels of gas, lava projectiles coming out of the volcano during an eruption, do not go very high.
Conclusion:
The viscosity of the magma & lava material are what provide the volcano structure. When it’s sticky – it has the ability to build on its self. Stickier materials have the ability to adhere better than runny material. When the magma / lava is runny, it tends to ooze outward instead of building upward – which is one of the reasons why the shield volcano is wide at the base compared to its height.
The gas levels of the volcano will affect the type of eruption. With high levels of gas, the volcano has the means to shoot molten rocky material high into the sky. With low levels of gas, the volcano seems to peter out, and doesn’t have the ability to get things moving.
The viscosity of the magma & lava material are what provide the volcano structure. When it’s sticky – it has the ability to build on its self. Stickier materials have the ability to adhere better than runny material. When the magma / lava is runny, it tends to ooze outward instead of building upward – which is one of the reasons why the shield volcano is wide at the base compared to its height.
The gas levels of the volcano will affect the type of eruption. With high levels of gas, the volcano has the means to shoot molten rocky material high into the sky. With low levels of gas, the volcano seems to peter out, and doesn’t have the ability to get things moving.
How they monitor Volcanoes
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Brief Explanation on Volcanoes & Super Volcanoes
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Movie:
Next, we watched a PBS NOVA video on the "Deadliest Volcanoes". Students are required to fill up one page with open notes.
Here are some additional links:
Next, we watched a PBS NOVA video on the "Deadliest Volcanoes". Students are required to fill up one page with open notes.
Here are some additional links:
- PBS video on Deadliest Volcanoes (On this site, take one page of notes on the documentary from Nova).
- PBS video on Mount St. Helens, Back from the dead