Class 11 Geography Important Chapter 5 Earthquakes and Volcanoes

Class 11 Geography Important Chapter 5 Earthquakes and Volcanoes Solutions English Medium As Per AHSEC New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters ASSEB Class 11 Geography Important Solutions and select need one. AHSEC Class 11 Elective Geography Additional Notes English Medium Download PDF. HS 1st Year Finance Important Solutions in English.

Class 11 Geography Important Chapter 5 Earthquakes and Volcanoes

Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. ASSEB Class 11 Elective Geography Additional Question Answer are part of All Subject Solutions. Here we have given HS 1st Year Elective Geography Important Notes in English for All Chapters, You can practice these here.

Earthquakes and Volcanoes

Chapter: 5

SECOND UNIT : OUR EARTH

IMPORTANT QUESTION AND ANSWER

Answer The Following Questions:

1. What is an Epicentre?

Ans: The point on the Earth’s surface that lies directly above the focus (the point inside the Earth where an earthquake originates) is called the epicentre.

2. What are the main parts of a volcano?

Ans: The four main parts of a volcano are — (i) Magma, (ii) Vent, (iii) Crater, and (iv) Lava cone.

3. What percentage of the world’s earthquakes occur in the Pacific region, known as the Circum-Pacific Belt?

Ans: About 68% of the world’s earthquakes occur in the Circum-Pacific Belt.

4. What is meant by internal force?

Ans: The forces that originate within the Earth and cause deformation of the Earth’s crust are called internal forces.

5. What is an Earthquake?

Ans: A sudden vibration or shaking of the Earth’s crust caused by internal pressure or stress is called an earthquake.

6. How many main causes are identified under crustal disequilibrium?

Ans: Three main causes are identified under crustal disequilibrium.

7. What is a Dormant Volcano?

Ans: A volcano that has not erupted for a long time but may erupt again in the future is called a dormant volcano.

8. What are the types of volcanoes?

Ans: The main types of volcanoes are — (i) Active volcanoes, (ii) Dormant volcanoes, and (iii) Extinct volcanoes.

9. What is the name of the material that comes out and accumulates on the surface during an eruption?

Ans: The material that comes out and accumulates on the Earth’s surface during an eruption is called lava.

10. During which year did a part of Japan’s land sink 6 metres below the surface due to an earthquake?

Ans: In the year 1891, a part of Japan’s land sank 6 metres below the surface due to an earthquake.

Long Question & Answer:

1. Explain the main causes of changes in the Earth’s crust.

Ans: The changes in the Earth’s crust are slow, natural, and continuous processes caused by two types of forces — internal and external.

(i) Internal forces originate inside the Earth and include heat, pressure, radioactivity, and convection of magma. These cause mountain building, folding, faulting, earthquakes, and volcanic eruptions.

(ii) External forces such as wind, rainfall, rivers, glaciers, and sea waves reshape the Earth’s surface through erosion, transportation, and deposition, leading to the formation of valleys, deltas, and plains.

2. What is Orogenic movement?

Ans: Orogenic movement refers to the process of mountain building. The mantle below the Earth’s crust contains semi-molten material, which moves due to heat and pressure, creating convection currents. These currents exert horizontal pressure on the crust, causing it to fold and uplift into mountains. Such movements are called horizontal or orogenic movements, responsible for mountain formation.

3. What is an Earthquake? Discuss its causes.

Ans: An earthquake is the sudden shaking of the Earth’s crust due to stress developed in the mantle below.

Main causes:

(i) Plate movement: When tectonic plates collide or move apart, they create pressure, causing vibrations.

(ii) Volcanic eruptions: When magma, gas, and steam escape from the mantle through cracks, violent eruptions cause tremors.

(iii) Crustal imbalance: Uneven pressure or temperature changes in the mantle can also lead to crustal adjustment and earthquakes.