Read the following statement related to 'Earthquake shadow zone' and choose the correct option:
Statement I : The shadow zone of one earthquake is totally different from the shadow zone of another earthquake
Statement II : Seismometers record both 'P' and 'S' waves at any distance out of 105°
from earthquake's epicentre
Correct Answer:
(B) Statement I is true, but Statement II is false
Earthquake waves get recorded is seismographs. However, there exist some specifi c areas where the waves are not reported. Such a zone is called the 'Shadowzone'. The study of different events reveals that for each earthquake, there exists an altogether different shadow zone. Also, seismometers record both 'P' and 'S' waves at any distance within 105o from earthquake's epicentre.
Ques: 2
The place on earth's surface which records the seismic waves first, is called
Correct Answer:
(B) Epicentre
Earthquakes are vibrations of the Earth, caused by the rupture and sudden movement of rocks that have been strained beyond their elastic limits.
(a) Focus – The point of origin of an earthquake.
(b) Epicentre–The point of the Earth's surface which is
directly above the focus of an earthquake. Hence it is where seismic waves are recorded first.
(c) Seismosite is a scientific instrument which was earlier used to measure seismic activity.
Ques: 3
The ‘Ring of Fire’ is associated with
1. Earthquake 2. Volcanoes
3. Pacific Ocean 4. Forest Fires
Choose your answer with the help of codes given below :
Code :
Correct Answer:
(A) 1, 2 and 3
‘Rings of fire’ is a region in the Pacific Ocean influenced by volcanic activities and Earthquake. Approximately 90% of the world's earthquakes occur along the 'Ring of fire'. The region of ‘Rings of fire’ includes the vast seismic zone of Chile, California, Alaska, Japan, Philippines, New Zealand and part of Central Ocean. There are three main regions in the Ring of fire –
Intersection point of Ocean and land
New twisted mountainous terrain
Volcanic field
Ques: 4
Consider the following statements :
The Richter scale is a logarithmic scale and so an increase of 1 magnitude unit represents a factor of 10 in amplitude.
Each integer reading of the Richter scale has an energy 100 times than the previous integer reading.
Which of the statement(s) given above is/are correct?
Correct Answer:
(A) 1 only
The magnitude of the earthquake is measured on the Richter scale and intensity on Mercalli scale. In 1935, seismologist Charles Francis Richter of the California Institute of Technology developed the Richter magnitude scale. It is based on a logarithmic scale which is mentioned as 1-10 on the scale. Each number of seismographs represents 10 times amplitude, 32 times energy. A seismic wave of intensity 1 releases the energy of 6 ounces of TNT. Hence statement (1) is correct while statement (2) is wrong.
Ques: 5
Consider the following statement about earthquake –
Intensity of earthquake is measured on Mercalli Scale.
Earthquake’s magnitude is the measurement of energy released.
Magnitude of earthquake depends directly upon Amplitude of an earthquake waves.
Every integer on Richter Scale shows 100 times increase in energy released
Which of the statements are true?
Correct Answer:
(A) 1, 2 and 3
The intensity of an earthquake is measured by Mercalli scale. Hence, statement (1) is correct. The magnitude of earthquake is the measurement of energy released; thus statement (2) is correct. Richter scale has a shaking amplitude 10 times that of the previous integer and shows an increase of 32 times in energy. Energy equal to 6 ounces of TNT is released by an earthquake of a magnitude of 1. Hence statement (3) is correct but statement (4) is false.
Ques: 6
Richter Scale is used to measure –
Correct Answer:
(A) Intensity of earthquake
Ques: 7
Seismometer measures –
Correct Answer:
(C) Earthquake
The seismometer is an instrument to record, magnitude and intensity of an earthquake. Crescograph is used to measure the height of trees and Cardiogram is an instrument to measure heartbeat.