earthquakes
DESCRIPTION
about earthquakesTRANSCRIPT
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
2/4www.sakshieducation.com/(S(ccdwnnrdm3250u3pwyeg4145))/GroupII/GIIPDFStory.aspx…
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
3/4www.sakshieducation.com/(S(ccdwnnrdm3250u3pwyeg4145))/GroupII/GIIPDFStory.aspx…
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
4/4www.sakshieducation.com/(S(ccdwnnrdm3250u3pwyeg4145))/GroupII/GIIPDFStory.aspx…
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)