INTERIOR OF THE EARTH Flashcards
Direct Sources of earths interior
Mining, drilling, volcanic eruption
InDirect Sources of earths interior
Analysis of temeperature and pressure, meteors, gravitation, magnetic field, and seismic activity
lithosphere refers to the portion of depth
up to 200 km from the
surface of the earth
Two types of body waves
p and s waves
waves are similar to sound waves. They travel
through gaseous, liquid and solid materials
The P-waves
Shadow zone of P waves
105 to 145
Shadow zone of s waves
beyonf 105
collapse earthquakes
In the areas of intense mining activity,
sometimes the roofs of underground
mines collapse causing minor tremors
explosion earthquakes.
Ground shaking may also occur due to the explosion of chemical or nuclear devices
Types of Earthquakes
tectonic earthquakes, volcanic earthquake. collapse earthquakes explosion earthquakes. reservoir induced earthquakes
The magnitude scale is known as the
Richter scale 0 to 10
The intensity scale is named after
Mercalli, 1 to 12
The mean thickness of
oceanic crust is
5 km
The mean thickness of the
continental is around
30 km
mean density of oceanic crust is
2.7g/cc
mean density of continental crust
3 g/cc
type of rock in oceanic crust is
basalt
The mantle extends from
Moho’s discontinuity to a depth of 2,900 km.
The upper portion of the mantle is called
asthenosphere. extending upto 400 km.
Main source of magma
asthenosphere.
density in asthenosphere.
3.4g/cc higher than crust
The crust and the uppermost part of the mantle are called
lithosphere. Its thickness ranges from 10-200 km
The core mantle boundary is located at the depth of
2,900 km.
Nife layer
core
density at core mantle boundary
5 g/cc
density at core centre
13g/cc
magma.
The material in the upper mantle portion
are the largest of all the volcanoes on the earth.
Shield volcanoes
Shield volcanoes
basalt, very fluid, generally low explosivity
cinder cone found in
Shield volcanoes
characterised by eruptions of cooler and more viscous lavas than basalt and explosive eruptions
Composite Volcanoes
These are the most explosive of the earth’s
volcanoes.
Calderas
tend to collapse on themselves rather than building any tall structure. The collapsed depressions are called
calderas.
Intrusive Volcanic Forms
Batholiths, Lacoliths, Lapolith, Phacolith and Sills, dykes
These are large dome-shaped intrusive bodies
with a level base and connected by a pipe-like conduit from below
Lacoliths Karnataka plateau
develops into a saucer shape, concave
to the sky body, it is called
lapolith
A wavy mass of intrusive rocks, at times, is found at
the base of synclines or at the top of anticline
in folded igneous country.
phacoliths
The near horizontal bodies of theintrusive igneous
rocks are called
sill or sheet (thinner)
