Earth's Interior UPSC IAS

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Video Series on Geography (GS)
INTERIOR OF THE EARTH

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Why know
about
Earth’s
Interior
Sources of
information
about the
interior
Types of
Earthquake
Waves (Seismic
waves)
Layers of
Earth
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INTERIOROFTHEEARTH
Why know about Earth’s Interior
Exogenic and
Endogenic
process
Geographical
phenomenon
Internal
structure of solar
system objects
Atmosphere
Deep sea
mining
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INTERIOROFTHEEARTH
Sources of information about the interior
Sources
Direct
sources
Deep earth
mining and
drilling
Volcanic
eruptions
Indirect
sources
Gravitation
MeteorsMagnetic field
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INTERIOROFTHEEARTH
Explanation for some sources
Evidences from Meteorites

INTERIOROFTHEEARTH
Explanation for some sources
Seismic waves

Types of Earthquake Waves (Seismic waves)
INTERIOROFTHEEARTH
Earthquake
waves
Body waves
Primary
waves
Secondary
waves
Surface
waves

INTERIOROFTHEEARTH
Primary waves or P-waves
 Longitudinal waves or
Compressional waves
 High frequency long wavelength
 First to arrive at the surface.
 Travel in all mediums
 Velocity: Solid > Liquids >
Gases

INTERIOROFTHEEARTH
Secondary waves or S-waves
 Transverse waves or
distortional waves
 High frequency long
wavelength
 Arrives after P-waves
 Cannot travel in liquids
and gases.

INTERIOROFTHEEARTH
Surface waves
 Transverse waves
 Low frequency and long
wavelengths
 P-waves and S-waves
interact with rocks to
generate Surface waves
 Localized waves
 Most destructive

Shadow zoneINTERIOROFTHEEARTH
S-waves

Shadow zoneINTERIOROFTHEEARTH
P-waves

General Science related
 Why does sound
wave travel faster
in a denser
medium whereas
light travels
slower?
 Why S-waves
cannot travel
through liquids?
INTERIOROFTHEEARTH

Layers of EarthINTERIOROFTHEEARTH

Layers of Earth
INTERIOROFTHEEARTH

Layers of Earth
INTERIOROFTHEEARTH
 Surface to Mohorovic
discontinuity
 30-50 km; 30-100 km; 5-30 km
 0.5 – 1.0 %
 Density 2-3.
 Surface made of granitic rocks
 Below layer is igneous and
metamorphic (acidic)
 Bottom layer basic and
ultrabasic rocks
Crust
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Layers of Earth
INTERIOROFTHEEARTH
 35-2900 km; 16%
 Solid rock and magma
 Density ~3; In lower parts 3.3 – 5.7
 Outer layer is partly simatic
 Inner layer is simatic with
ultrabasic rocks.
Asthenosphere
 M-discontinuity to 400km
 Important role in plate tectonics
Mantle
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Layers of Earth
INTERIOROFTHEEARTH
 2900 – 6400 km
 83%
 Gutenberg discontinuity  A
zone of mixed heavy metals +
silicates separates the core from
outer layers
 Nife
 Outer core  liquid
 Inner core  solid
 Density varies from 10 to 13
Core
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Composition of Earth’s Crust
INTERIOROFTHEEARTH

INTERIOROFTHEEARTH
Composition of Earth
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INTERIOROFTHEEARTH
Questions from Previous Papers
In the structure of planet Earth, below the mantle,
the core is mainly made up of which one of the
following? , [2009]
(a) Aluminium
(b) Chromium
(c) Iron
(d) Silicon
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Earth's Interior UPSC IAS

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