Class 11 Geography CBQ Chapter 3 - Interior of the earth
Source-Based Questions:
Read the paragraph below and answer the following questions:
All the earthquake waves are travelling through the earth in different ways and they cause vibrations in the rocks through which they passing through. One important wave pass through the same direction as its vibration and as a result of their vibration pressure creates and changes in density within the materials. All of the other earthquake waves move at a right angle to their wave direction in a vertical plane. During the time movement of these waves create troughs and crest producing wave-like motions. Among these earthquake waves surface waves are more destructive wave as they strongly disturb the surface of the earth.
(Note: This paragraph is not directly taken or copied from the NCERT book but based on the concept it is rewritten in original language)
Question 1. Which earthquake wave reach to the ground first from the focus?
Answer: P-wave or primary waves reach to the ground first from the focus or source area of the earthquake.
Question 2. How do the P-waves move through the earth?
Answer: Primary or P waves moves parallel to their direction of movement and create pressure within the rocks.
Question 3: How the P waves are different from S waves?
Answer: (give answer as per marks)
- P wave can move through three different states of matters - solid, liquid and gas, but s wave can travel through solid materials only.
- P is the first wave to arrive to the surface of the earth, but s wave arrives after some time of p waves arrival.
- P wave pass through the same direction as its vibration or propagation, but s wave moves perpendicular to the direction of propagation.
- P wave is less destructive as compare the s wave.
Question 4: Which earthquake waves cause maximum damage to the earth surface and why?
Answer: Surface wave causes maximum destruction on the earth surface. Because this wave generates more vibration or strong motion on the ground.
Observe the given picture carefully and answer the followings:
Question 1. Which type of volcanoes shown in the diagram marked as 'A'?
Answer: In this diagram composite volcano is shown here marked as 'A'.
Question 2. Which type of landform is shown by 'B,?
Answer: Sill is shown here by 'B' point which is intrusive landform of volcano.
Question 3: What is the name of the landform marked by 'C'?
Answer: This type of landform created by the vertical deposition of magma is known as Dyke.
Question 4: Name the landform marked as 'D'?
Answer: Batholiths - this is the solidified magma chamber.
Question 5: What is the name of special type of landform marked by 'E'?
Answer: This is the large size dome shaped deposition of magma which is connected with the main magma chamber with a pipe like volcanic conduit known as laccolith.
Question 6: Which landform is shown using the letter 'F'?
Answer: Caldera - this is the collape depression of the volcanic mountain in the top of the mountain.
Question 1: What is the name of the area marked by 'A'?
Answer: 'P'-waves shadow zone (from 105° to 145° from epicentre).
Question 2: What is the name of the area marked by 'B'?
Answer: 'S'-waves shadow zone, as this wave can't move through the liquid state (upper core).
Question 3: What is the name of the layer of the earth marked by 'C'?
Answer: The core.
Question 4: What is the name of the uppermost part of the earth marked by 'D'?
Answer: The crust is the uppermost part of the earth and here SIAL part of the earth crust is marked by 'A'.
Question 5: Which layer marked by 'E' and why this layer is important?
Answer: The 'E' layer is the asthenosphere layer of the earth. This layer is important as because of the presence of magma where all lithospheric plates are floating.
Question 6: Name the layer marked by 'F' and 'G' respectively. Which type of composition of materials are there?
Answer: 'F' and 'G' is outer and inner core respectively and this layer is mainly made up of nickel and ferrous. Therefore, this layer also known as 'NIFE'.
Question 7: Which type of volcano is shown in the picture marked as 'H'? Give an example of such type of volcano.
Answer: Shield volcano is marked by 'H'. Hawaiian volcano is an example of shield volcano.
Other Important key points
- What is gravity anomaly?
Answer: Gravity is the power of attraction of anything towards the centre of the earth. It is higher near the pole but less near the equator as the distance between centre to the pole is less and centre to the equator is more respectively.
The reading of the gravity of any places influenced by many other factors. Therefore, the value of gravity differs from place to place from the expected value of gravity. Such differences of gravity is known as gravity anomaly. - What is Hypocentre or Epicentre?
Answer: The hypocentre is commonly known as focus of the earthquake. The point from which energy released and earthquake starts is known as focus or hypocentre.
On the other hand, the nearest point from the focus or hypocentre on the earth surface is known as epicentre. This is the first place to experience the earthquake and locates directly above the focus on the earth surface.