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Niamh Cooke
10/08/2025
Geography
Volcano and Tectonic Revision Sheet
1,116
•
10 Aug 2025
•
A-Level Geography: Volcanoes, Tectonic Hazards, and Plate Boundaries
Niamh Cooke
@niamhcooke_yelp
Plate Boundaries and Volcanic Eruptions
This page focuses on the types of plate boundaries and volcanic eruptions, which are crucial concepts in understanding what happens at a destructive plate boundary and other tectonic processes.
Types of Plate Boundaries
- Destructive/Convergent Boundaries:
- Oceanic/Oceanic: The older, more dense plate subducts below the other, which is then heated and melts as it is forced deeper into the chamber. This process forms oceanic trenches.
- Continental/Continental: Causes a powerful collision, as both plates are equally dense, preventing subduction. This process forms mountain ranges, such as the Himalayas.
Example: The Mariana Trench, located in the western Pacific Ocean, is an example of a destructive plate boundary where oceanic-oceanic subduction occurs.
- Constructive Boundaries:
- Continental/Continental: Plates move away from each other. The overlying plate is stretched thin until it breaks, causing earthquakes. This process forms rift valleys, and streams/rivers flow into the ridge to form long lakes.
Highlight: Understanding constructive boundaries is essential for grasping what happens at a constructive plate boundary in A-level Geography.
- Conservative Boundaries:
- Mainly found on the ocean floor.
- Plates slide past each other, either at different speeds or in different directions.
- No volcanic activity occurs, but may cause shallow focus earthquakes.
Example: The San Andreas Fault in California is a well-known conservative plate boundary example.
Types of Volcanic Eruptions
-
Hawaiian Type: Lava slowly and easily escapes the vent. It is very runny and basaltic, resulting in gently sloped volcanoes.
-
Strombolian: Gas explosions occur more frequently. Small but very frequent eruptions.
-
Vulcanian: More violent but less frequent than Strombolian. Plugs of cooled lava may be ejected in blasts.
-
Vesuvian: Extremely strong explosions, often occurring after a volcano has been lying dormant for a while. Gas and ash clouds fall over vast areas.
-
Krakatoan: Exceptionally violent eruptions.
-
Plinian: Usually the most violent, with massive amounts of lava, gas, and pyroclastic flow. Part of the volcano may be removed during the eruption.
Vocabulary: Plinian eruption - An extremely violent volcanic eruption characterized by a tall, umbrella-shaped cloud of ash and gas that can reach the stratosphere.
Understanding these types of eruptions is crucial for students studying volcanic hazards in A-level Geography and learning about the three types of volcanic eruptions.
Types of Volcanoes
This page provides an overview of various volcano types and their characteristics, which is essential for understanding tectonic hazards in A-level geography.
Shield Volcanoes are formed from basaltic rock and have gently sloping cones due to less viscous lava. They are typically found in hot spots and above double oceanic plate boundaries, with gentle and predictable eruptions.
Vocabulary: Basaltic rock - A type of igneous rock formed from cooled lava, typically dark in color and low in silica content.
Cinder Cone Volcanoes are the most common type, characterized by symmetrical cones that may occur as single or secondary cones. They are formed by airborne fragments of lava ejected from the vent, building up layers.
Calderas are formed when gases build up under a blocked vent, resulting in internal eruptions that create huge craters at the summit. They are found on destructive plate boundaries and cause very explosive and unpredictable eruptions.
Example: The Yellowstone Caldera in Wyoming, USA, is one of the largest known calderas in the world.
Acid/Dome Cone Volcanoes have steep sides and form from very viscous lava. They are often found on continental crusts and cause explosive and unpredictable eruptions. The rock type associated with these volcanoes is Rhyolitic.
Composite Volcanoes are the most common on land and are found on destructive plate boundaries. They cause explosive and unpredictable eruptions.
Highlight: Understanding the different types of volcanoes is crucial for revising A-level geography and comprehending the theory of plate tectonics.
The page also mentions volcanic hotspots, which are caused by a concentration of radioactive elements inside the mantle. A plume of magma rises from these hotspots to eat into the plate above, creating an active volcano where lava breaks through.
Volcanic hazards are also discussed, including:
- Ash Clouds: Small pieces of pulverized rock and gas shot into the atmosphere.
- Volcanic Gases: Sulphur dioxide, water vapor, and carbon dioxide emitted from volcanoes.
- Lahars: Volcanic mudflows that usually run down valleys on volcanoes.
- Pyroclastic Flows: Fast-moving currents of super-heated gas and ash, reaching temperatures of 1000°C and traveling at speeds up to 450 mph.
- Volcanic Bombs: Thick viscous lava fragments ejected from the mouth of a volcano.
Definition: Pyroclastic flow - A dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases that occurs during certain volcanic eruptions.
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
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This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
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Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
A-Level Geography: Volcanoes, Tectonic Hazards, and Plate Boundaries
Niamh Cooke
@niamhcooke_yelp
Volcanoes are a crucial topic in A-level Geography, covering various types, formations, and associated hazards. This summary explores the different volcano types, their characteristics, and the plate boundaries that influence volcanic activity. It also delves into volcanic hazards and eruption... Show more
Plate Boundaries and Volcanic Eruptions
This page focuses on the types of plate boundaries and volcanic eruptions, which are crucial concepts in understanding what happens at a destructive plate boundary and other tectonic processes.
Types of Plate Boundaries
- Destructive/Convergent Boundaries:
- Oceanic/Oceanic: The older, more dense plate subducts below the other, which is then heated and melts as it is forced deeper into the chamber. This process forms oceanic trenches.
- Continental/Continental: Causes a powerful collision, as both plates are equally dense, preventing subduction. This process forms mountain ranges, such as the Himalayas.
Example: The Mariana Trench, located in the western Pacific Ocean, is an example of a destructive plate boundary where oceanic-oceanic subduction occurs.
- Constructive Boundaries:
- Continental/Continental: Plates move away from each other. The overlying plate is stretched thin until it breaks, causing earthquakes. This process forms rift valleys, and streams/rivers flow into the ridge to form long lakes.
Highlight: Understanding constructive boundaries is essential for grasping what happens at a constructive plate boundary in A-level Geography.
- Conservative Boundaries:
- Mainly found on the ocean floor.
- Plates slide past each other, either at different speeds or in different directions.
- No volcanic activity occurs, but may cause shallow focus earthquakes.
Example: The San Andreas Fault in California is a well-known conservative plate boundary example.
Types of Volcanic Eruptions
-
Hawaiian Type: Lava slowly and easily escapes the vent. It is very runny and basaltic, resulting in gently sloped volcanoes.
-
Strombolian: Gas explosions occur more frequently. Small but very frequent eruptions.
-
Vulcanian: More violent but less frequent than Strombolian. Plugs of cooled lava may be ejected in blasts.
-
Vesuvian: Extremely strong explosions, often occurring after a volcano has been lying dormant for a while. Gas and ash clouds fall over vast areas.
-
Krakatoan: Exceptionally violent eruptions.
-
Plinian: Usually the most violent, with massive amounts of lava, gas, and pyroclastic flow. Part of the volcano may be removed during the eruption.
Vocabulary: Plinian eruption - An extremely violent volcanic eruption characterized by a tall, umbrella-shaped cloud of ash and gas that can reach the stratosphere.
Understanding these types of eruptions is crucial for students studying volcanic hazards in A-level Geography and learning about the three types of volcanic eruptions.
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Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Types of Volcanoes
This page provides an overview of various volcano types and their characteristics, which is essential for understanding tectonic hazards in A-level geography.
Shield Volcanoes are formed from basaltic rock and have gently sloping cones due to less viscous lava. They are typically found in hot spots and above double oceanic plate boundaries, with gentle and predictable eruptions.
Vocabulary: Basaltic rock - A type of igneous rock formed from cooled lava, typically dark in color and low in silica content.
Cinder Cone Volcanoes are the most common type, characterized by symmetrical cones that may occur as single or secondary cones. They are formed by airborne fragments of lava ejected from the vent, building up layers.
Calderas are formed when gases build up under a blocked vent, resulting in internal eruptions that create huge craters at the summit. They are found on destructive plate boundaries and cause very explosive and unpredictable eruptions.
Example: The Yellowstone Caldera in Wyoming, USA, is one of the largest known calderas in the world.
Acid/Dome Cone Volcanoes have steep sides and form from very viscous lava. They are often found on continental crusts and cause explosive and unpredictable eruptions. The rock type associated with these volcanoes is Rhyolitic.
Composite Volcanoes are the most common on land and are found on destructive plate boundaries. They cause explosive and unpredictable eruptions.
Highlight: Understanding the different types of volcanoes is crucial for revising A-level geography and comprehending the theory of plate tectonics.
The page also mentions volcanic hotspots, which are caused by a concentration of radioactive elements inside the mantle. A plume of magma rises from these hotspots to eat into the plate above, creating an active volcano where lava breaks through.
Volcanic hazards are also discussed, including:
- Ash Clouds: Small pieces of pulverized rock and gas shot into the atmosphere.
- Volcanic Gases: Sulphur dioxide, water vapor, and carbon dioxide emitted from volcanoes.
- Lahars: Volcanic mudflows that usually run down valleys on volcanoes.
- Pyroclastic Flows: Fast-moving currents of super-heated gas and ash, reaching temperatures of 1000°C and traveling at speeds up to 450 mph.
- Volcanic Bombs: Thick viscous lava fragments ejected from the mouth of a volcano.
Definition: Pyroclastic flow - A dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases that occurs during certain volcanic eruptions.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user