CLG# 5
Layer
Thickness
Temperature
Composition
Crust
Oceanic (5km to 10
km)
Continental (30 km
to 50km)
about 200 °C to
400 °C
oxygen (46.6%), silicon
(27.7), aluminum (8.1),
iron (5.0), calcium (3.6),
potassium (2.8), sodium
(2.6), and magnesium
(2.1).
Mantle
2,900 km
500° to 900 °C
Outer Core
2,200 km
4400 °C to 6100 °C
iron and nickel
Inner Core
1250 km
6,000°C
nickel-iron alloy
made up of rock
containing silicon, iron,
magnesium, aluminium,
oxygen and other
minerals.
DISCONTINUITIES
Conrad Discontinuity- corresponds to the
sub-horizontal boundary in continental crust
at which the seismic wave velocity increases
in a discontinuous way.
Moho Discontinuity- lies almost entirely
within the lithosphere; only beneath midocean ridges
Repetti Discontinuity- between upper and
lower mantle.
Guttenberg Discontinuity- Between lower
mantle and outer core
Lehman Discontinuity- Between outer and
inner core
Which wave is detected
first in the Earth’s
surface?
Seismic Wave
Crust
Mantle
Outer Core
Inner Core
P wave
Yes (but are
slowed in the
boundary of the
crust and
mantle)
Yes
Yes
Yes
S wave
Yes
Yes
No (passing from
the mantle to the
core are absorbed
because s waves
cannot be
transmitted through
liquids. )
No
The wave is the P wave
or primary wave. This is
the fastest kind of
seismic wave, and,
consequently, the first to
'arrive' at a seismic
station. The P wave can
move through solid rock
and fluids, like water or
the liquid layers of the
earth.
Lithosphere- the rigid outer part of
the earth, consisting of the crust and
upper mantle.
Asthenosphere- the upper layer of
the earth's mantle, below the
lithosphere, in which there is
relatively low resistance to plastic
flow and convection is thought to
occur.
Tectonic plates are pieces of Earth's
crust and uppermost mantle