The Earthquake

11. The place on earth's surface which records the seismic wave first, is called: [U.P.R.O./A.R.O. (Pre) 2017]

(a) Focus
(b) Epicentre
(c) Seismosite
(d) None of the above

Correct Answer: (b) Epicentre

Solution:The point where the energy is released is called the focus of an earthquake. The point/place where the seismic waves are first recorded is called the Epicentre. This is the point on the Earth's surface directly above the focus. It's the location where the earthquake's effects are most intense. The epicenter is the location that is generally shown in media reports when an earthquake occurs.

12. Cocos Plate lies between- [63rd B.P.S.C. (Pre) 2017]

(a) Central america and Pacific Plate
(b) South America and Pacific Plate
(c) Red Sea and Persian Gulf
(d) Asiatic Plate and Pacific Plate
(e) None of the above/More than one of the above

Correct Answer: (a) Central america and Pacific Plate

Solution:The Cocos Plate lies between Central America and pacific Plate. A tectonic plate (also called lithospheric plate) is a massive, irregularly-shaped slab of solid rock, generally composed of both continental and oceanic lithosphere. The lithosphere includes the crust and top mantle with its thickness range varying between 5-100 km in oceanic parts and about 200 km in the continental areas. The concept of Tectonic Plates was first introduced in 1967. A tectonic plate may be a continental plate or an oceanic plate, depending on which of the two occupies the larger portion of the plate. The Pacific plate is largely an oceanic plate whereas the Eurasian plate is a continental plate.

13. Consider the following statement about earthquake- [I.A.S. (Pre) 2001]

1. Intensity of earthquake is measured on Mercalli Scale.

2. Earthquake's magnitude is the measurement of energy released.

3. Magnitude of earthquake depends directly upon Amplitude of an earthquake waves.

4. Every integer on Richter Scale shows a 100 times increase in energy released

Which of the statements are true?

(a) 1, 2 and 3
(b) 2, 3 and 4
(c) 1 and 4
(d) 1 and 3

Correct Answer: (a) 1, 2 and 3

Solution:

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 release. 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.

14. Richter Scale is used to measure - [Uttarakhand P.C.S. (Mains) 2002]

(a) Intensity of earthquake
(b) Depth of Ocean
(c) Velocity of Sapcecraft
(d) Height of a building

Correct Answer: (a) Intensity of earthquake

Solution:Through the Richter scale is not used to measure intensity of earthquake (Mercalli scale measures it), here option (a) is assumed to be correct. This is because option (a) is closest to the question asked. The intensity scale is named after Mercalli, an Italian seismologist. (The Mercalli Scale is based on observable earthquake damage. From a scientific standpoint, the magnitude scale is based on seismic records while the Mercalli is based on observable data which can be subjective).
Source: NCERT Class 11

15. The intensity of earthquakes is measured [U.P. Lower Sub. (Pre) 2015]

(a) On the Richter scale
(b) On the Kelvin scale
(c) In decibel
(d) In Pascal

Correct Answer: (a) On the Richter scale

Solution:Through the Richter scale is not used to measure intensity of earthquake (Mercalli scale measures it), here option (a) is assumed to be correct. This is because option (a) is closest to the question asked. The intensity scale is named after Mercalli, an Italian seismologist. (The Mercalli Scale is based on observable earthquake damage. From a scientific standpoint, the magnitude scale is based on seismic records while the Mercalli is based on observable data which can be subjective).
Source: NCERT Class 11

16. Seismometer measures- [Uttarakhand Lower (Sub.) (Pre) 2010]

(a) Heartbeat
(b) Height of trees
(c) Earthquake
(d) None of the above

Correct Answer: (c) Earthquake

Solution:The seismometer is an instrument to record, magnitude of an earthquake. Crescograph is used to measure the growth of plants, trees and Cardiogram is an instrument to measure heartbeat. A seismometer is the internal part of the seismograph, either a pendulum or a mass mounted on a spring.