CHANGES ON THE EARTH'S SURFACE DUE TO EARTHQUAKES AND VULCANIC ERUPTIONS

 CHANGES ON THE EARTH'S SURFACE DUE TO EARTHQUAKES AND VULCANIC ERUPTIONS

Describe the changes on the Earth’s surface as a result of earthquakes and volcanic eruptions

S6ES - IVa - 1

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Lecture Notes: Changes on the Earth's Surface due to Earthquakes and Volcanic Eruptions

Introduction:
- Earthquakes and volcanic eruptions are natural phenomena that can cause significant changes on the Earth's surface.
- They are both related to the movement and activity of tectonic plates, which make up the Earth's crust.
- In this lecture, we will explore the effects of earthquakes and volcanic eruptions on the Earth's surface.

I. Earthquakes:
A. Definition and Causes:
- An earthquake is a sudden shaking or trembling of the Earth's surface caused by the release of energy in the Earth's crust.
- Most earthquakes occur along plate boundaries where tectonic plates interact.
- The main cause of earthquakes is the movement and collision of tectonic plates.

B. Effects on the Earth's Surface:
1. Ground Shaking:
- During an earthquake, the ground shakes and vibrates, causing buildings, structures, and landforms to sway, crack, or collapse.
- This can lead to the destruction of infrastructure and changes in the landscape.

2. Faulting and Land Displacement:
- Earthquakes can create fractures in the Earth's crust called faults.
- Movement along faults can cause land displacement, resulting in the formation of new landforms or changes in existing ones.
- Examples of landforms formed by faulting include valleys, ridges, and scarps.

3. Tsunamis:
- Some earthquakes that occur under the ocean can trigger tsunamis, which are large ocean waves.
- When a tsunami reaches the shore, it can cause extensive flooding and erosion, leading to changes in coastal landscapes.

II. Volcanic Eruptions:
A. Definition and Causes:
- A volcanic eruption is the ejection of magma, gases, and other materials from a volcano.
- Volcanoes are formed when molten rock (magma) rises to the Earth's surface through vents and openings.

B. Effects on the Earth's Surface:
1. Lava Flows:
- During a volcanic eruption, molten lava flows down the sides of the volcano, covering the surrounding area.
- Lava flows can create new landforms, such as lava fields and volcanic cones, and modify existing landscapes.

2. Ashfall:
- Volcanic eruptions release ash, which is made up of tiny particles of rock, minerals, and volcanic glass.
- Ashfall can blanket large areas, covering the land and affecting ecosystems and human activities.
- It can also contribute to the formation of new soils over time.

3. Pyroclastic Flows and Lahars:
- Violent volcanic eruptions can generate pyroclastic flows, which are fast-moving clouds of hot gas, ash, and rock fragments.
- Pyroclastic flows can cause widespread destruction and reshape the landscape.
- Volcanic eruptions can also trigger lahars, which are mudflows or debris flows consisting of volcanic material mixed with water.

Conclusion:
- Earthquakes and volcanic eruptions are powerful natural events that shape the Earth's surface.
- They can cause various changes, including land deformation, formation of new landforms, destruction of structures, and alteration of ecosystems.
- Studying and understanding these processes are crucial for assessing and mitigating the impacts of these natural hazards.

Note: Students, please take the time to copy the lecture notes and review them for a better understanding of the topic. Feel free to ask questions if you need clarification on any point.

EXERCISES

Certainly! Here are 5 exercises for each topic: Changes on the Earth's Surface due to Earthquakes and Volcanic Eruptions.

Exercise 1: Earthquakes

1. Which of the following is the main cause of earthquakes?
   a) Volcanic activity
   b) Hurricane winds
   c) Movement of tectonic plates
   d) Global warming

2. True or False: Earthquakes can cause ground shaking and structural damage to buildings.

3. What are the landforms that can be formed by faulting during an earthquake?
   a) Mountains
   b) Valleys
   c) Canyons
   d) All of the above

4. A tsunami is:
   a) A volcanic eruption on land
   b) A type of earthquake
   c) A large ocean wave triggered by an earthquake
   d) A destructive windstorm

5. How can earthquakes affect coastal landscapes?
   a) By causing erosion
   b) By triggering landslides
   c) By generating tsunamis
   d) All of the above

Exercise 2: Volcanic Eruptions

1. What is ejected during a volcanic eruption?
   a) Water vapor
   b) Magma
   c) Lava lamps
   d) Sand

2. True or False: Lava flows from a volcanic eruption can create new landforms.

3. What is the term used for the tiny particles of rock, minerals, and volcanic glass that are released during a volcanic eruption?
   a) Lava
   b) Pyroclastic flow
   c) Ash
   d) Tsunami

4. What can be formed by the accumulation of volcanic ash?
   a) New soils
   b) Sand dunes
   c) Glaciers
   d) Coral reefs

5. What is a pyroclastic flow?
   a) A volcanic cone
   b) A cloud of hot gas and ash
   c) A type of earthquake
   d) A lava flow

Note: Students, please choose the correct answer for each question. You can refer to your lecture notes for assistance.

ANSWERS TO THE EXERCISES

Here are the correct answers for the exercises:

Exercise 1: Earthquakes

1. c) Movement of tectonic plates
2. True
3. d) All of the above
4. c) A large ocean wave triggered by an earthquake
5. d) All of the above

Exercise 2: Volcanic Eruptions

1. b) Magma
2. True
3. c) Ash
4. a) New soils
5. b) A cloud of hot gas and ash

Note: These answers correspond to the questions provided in the previous exercise. Make sure to check your responses against the correct answers.



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