Earthquakes

9/3/12 Earthquakes

1/4www.sakshieducation.com/(S(ccdwnnrdm3250u3pwyeg4145))/GroupII/GIIPDFStory.aspx…

Education Home | Contact | Feedback

Home Current Affairs General Essay Mock Tests Bit Banks Civils Special Ask The Expert DSC GK

Group II / Group I PrelimsStudy Material

Group II Model Papers

Current Affairs Special

Indian History

Geography

Mental Ability

Sci & Tech

Biology

Physics

Chemistry

Group II Study Material

Paper II

AP History

Polity

Paper III

Indian Economy

AP Economy

Group I Mains StudyMaterial

Group I Prep. Guidance

Paper I

Paper II

Paper III

Paper IV

Paper V

Model Q & A

Study Material for Banks

Quantitative Aptitude

Computer Knowledge

Reasoning

General Awareness

DSC Study Material

Model Papers

Preparation Plan

Perspectives in Education

Language Pandit Telugu

English

School Assistant

Secondary Grade Teacher

Methodology

Earthquakes

I. Introduction:

1. Natural Disasters :

These are uncontrollable events that cause sudden and massive destruction, like the Earthquake in Gujarat. The extent of

damage to life and property is so extensive that normal socio-economic mechanisms of relief are rendered inadequate. Special

efforts are required to handle the situation.

2. Internal Security Concern :

Analysts point out that natural disaster affecting the survival of citizens is as much an internal security concern as external

aggression, internal subversion or centrifugal violence which affect our country.

3. Human Survival :

The ultimate benchmark for security in any civil society, in any country, is human survival, particularly when faced with

natural disasters, according to analysts. The climatic, territorial and environmental diversity of a large country like India are

bound to be subject to some kind of natural calamity. In recent times India has suffered from cyclones, earthquakes, floods

and tidals.

4. Earthquakes:

A series of shock waves in the earth's crust or upper mantle. They are the earth's natural means of releasing stress.

5.Cause of Earthquakes:

a. Presence of Fault Planes and other Stressful Environments:

Geological studies have revealed that earthquakes are caused by stresses within the earth. These stresses develop because of

instability in the geological formations below the earth due to the presence of fault planes and other stressful environments

like the internal heat of the earth. Under these conditions the rock bodies shift releasing energy in the form of shock waves

which can cause earthquakes.

b. Plate Movements:

Earthquakes are also caused by the movement of earth's plates- large, relatively rigid segments of the lithosphere (the solid,

rocky outer part of the earth's crust). When this stress is increased beyond a point, the earth's crust is forced to break. The

stress is released as energy which moves through the earth in the form of waves.

6.Earthquake Waves:

The shock waves which cause the earthquakes can be classified into two broad categories.

Surface Waves:

Travel through the surface of the earth.

Body Waves:

Travel through the body of the earth getting reflected and refracted in the process. The body waves can be further divided

Search

9/3/12 Earthquakes


Methodology

APTET Bit Bank

Paper I

Paper II

Solved Papers

Group – IV

GS, Mental Ability PracticeBits

General Studies

English

Secretarial Abilities

Previous Papers

Exam Resources

Syllabus

Previous Papers

Suggested Books

Reference Books for GroupIMains (EM)

Travel through the body of the earth getting reflected and refracted in the process. The body waves can be further divided

into the P (primary) and S (secondary) waves.

a. Different Velocities of Propagation in Different Mediums:

The velocities of propagation differ from one medium to another as the earth is non-homogenous and layered medium. The P

waves can travel through a solid as well as a liquid where as the S waves can travel only through a liquid medium.

b. Different Velocities of Propagation within the Same Medium:

The propagation velocities of P and S waves are also different within a given medium, with P waves travelling faster than S

waves. This difference in velocities is made use of by the earthscientists in locating the epicentre of the earthquakes.

7.Earthquake Terminology:

A.Plate Tectonics:

According to this theory the upper most 60-90 km thick layer of the earth called lithosphere, is divided into several large

and small plates. These plates which are floating on the lower layer of the earth called mantle, are constantly in motion and

interact with each other. The interacting margins of these plates are regions of severe deformation causing structural

dislocation and earthquakes.

B.Focus:

The centre of the earthquake, which is the source of seismic waves produced during an earthquake.

C.Epicentre:

The point on the earth's surface situated directly above the focus of an earthquake.

D. Intensity:

The measure of the ground shaking and damage to the surface and the effects on humans.

E. Magnitude:

The quantity to measure the size of an earthquake in terms of its energy.

F.Seismograph & Seismogram:

The instrument used for recording ground motions as a function of time is called a Seismograph and the records are known

as Seismograms. Using these Seismograms, scientists estimate the magnitude, epicentre and focal depth of the earthquake.

G. Richter Scale:

A logarithmic scale used for comparing the magnitude of earthquakes. It was invented by an American Seismologist, Charles

Richter in 1935.

Magnitude represents the amount of energy released by an earthquake as determined by measurements on standardised

instruments.

The scale ranges from 0 to 10. On this scale an earthquake of magnitude 8 represents seismograph amplitudes ten times

larger than those of Magnitude 7.

The largest earthquakes recorded were of magnitude of 8.9 (Lisbon, 1755) on the Richter scale and the smallest about minus

three.

H. Mercalli Scale:

9/3/12 Earthquakes


It is more subjective in assessing the effect of earthquakes. An earthquake registering 5 on the Mercalli scale is defined as

having made furniture to shake and church bells ring, but triggering little or no damage. But an earthquake measuring 12 on

the Mercalli scale would have destroyed all man-made objects, and created new topography by forming new lakes, huge falls

of rock and major earth faults. Russia has a 12 point scale and Japan a seven-point system.

I. Aftershocks:

Earthquakes triggered either on the mainshock fault- a fracture in the rock- or near it. Bigger earthquakes have more and

larger aftershocks.

J. Major Earthquakes since 1902:

DATE LOCATION DEATHS

1976 China 255,000

1920 China 200,000

1927 China 200,000

1923 Japan 143.00

1948 Turkmenistan 110,000

1908 Italy 70,000

1970 Peru 66,000

1990 Iran 50,000

1935 Pakistan 30,000

1993 India (Latur) 9,748

2001 India(

Gujarat)

13,800

2003 Iran 26,000

2004 Indonesia 283,106

2005 Pakistan &

North India

75,000

Related Topics..

India and the Global Financial Crisis… What Have We Learnt?

Changing Inflation Dynamics in India

Global Energy Security

Note: This page may require Adobe PDF Reader

to view files. Click Here to Download

9/3/12 Earthquakes


Transnational Gas Pipelines

CHINA

Bangladesh

IndoUS Relations

Russia

IndoFrench Relations

IndoSri Lankan Relations

Genetically Modified (GM) Foods

IndoJapanese Relations

India EU Relations

IndoEU Relations

IndoEU Relations

IndiaChina Relations

RIC: RussiaIndiaChina

SAARC Summit in Colombo

North Atlantic Treaty Organisation (NATO)

NonAligned Movement(NAM)

India A Rising Global Power

Disaster Management

Earthquake In China

Arctic Region Controversy

IBSA: IndiaBrazilSouth Africa

European Union (EU)

ASEAN

East Asia Summit (EAS)

New Start to Global Nuclear Arms Reduction

Swine Flu A(H1N1) Influenza

Impact of the Global Economic Crisis on India

Disaster Management

World Food Summit

Bird Flu (Avian influenza)

BRIC Brazil, Russia, India, China

SAARC Introduction

Group of Eight(G8)

Documents

Earthquakes