InteriorsSurface Activity

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Interiors/Surface Activity
Group 12
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Seismology
Seismology
Subject matter comprising means for detecting
and recording a seismic reflected or refracted
signal representative of earth vibrations.
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Earthquake
A sudden dislocation of rocky material near
Earth's surface.
Seismic Waves
The vibrations the earth withstands during an
earthquake.
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Fact
Seismic waves carry information which can be
detected and recorded using sensitive equipment.
Seismograph
Designed to monitor earth's tremors
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Modeling Earth's Interior
Waves
S waves (shear waves), the red Ones, are
blocked by earth's core
S Waves bounce off the outer core and make the
shadow zone
This is because S Waves can't pass through
liquid
Every earthquake makes these shadow zones and
these are the best evidence that the earth's
outer core is liquid
P Waves (pressure waves), the green ones, are
the other type of waves.
Can't pass through the inner core but can pass
through the outer core
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The Two causes of Differentiation
1. Earth was subjected to a violent bombardment
of interpalanetary debris, which prbably
generated enough heat to melt much of earth.
2. Radioactivity- The release of energy (heat) by
certain elements. These elements were spread out
throughout the primitive earth and kept it
molten for about a billion years.
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The moons average density is 3300km/m
This is similar to the density of the Moon's
surface rock.
This means that the moon probably has no heavy
core and has significantly fewer heavy elements,
such as iron, than does Earth.
The Moon's interior is probably of a uniform
density, but contains a variation of chemicals.
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The Moon's Core
Has a radius of 200km
Has more iron than does the rest of the moon.
The temperature is either too cold to melt
rock, or the core is partially molten.
The Moon's Crust
Is thicker on the far side (150km) than the
Earth side (60km) because when the Moon was
cooling, the lunar mantle was pulled towards the
Earth, so it is off center with the crust.
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Moon Facts
The Moon is geologically dead.
A moonquake releases about as much evergy as a
firecracker.
The Moon has a thick crust and a solid upper
mantle, unlike the Earth, which has a think
outer layer above a soft, convective region.
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A geologically Alive Earth
Geologically the earth is alive, and is
therefore constantly changing.
The best indicators of this activity
are Earthquakes and Volcanic Eruptions.
All of this activity is a result of continental
drift.
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Continental Drift, Plate Motion
Areas that have experienced active motion in
the last century, recognized as plate boundries.
Research in the 1960's discovered the drift of
these plates, thus causing the formation of
mountains and oceanic trenches.
Continents are mostly seen as passangers on
these plates, which are deep in Earth's surface.
Plates move only a few centimeters per year.
This motion could result in two continents
drifting, 4,000 kilometers from each other in
over 200 million years.
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Fault Line
Mountain ranges are the result of collisions
between plates.
However plates sometimes slide against each
other moving in different directions.
These motions occur in areas known as fault
line.
Fault line is where the boundries of two plates
meet and slide against each other in opposite
directions.
This motion does not happen in a smooth slow
motion, but rather harsh and jerky.
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Why the plates move
Plate movement is a result of convection.
Motion of the plates occurs when warmth builds
up inside the Earth's surface.
This warm matter is beneath the cool matter of
the Earth's surface and when it builds up
Convections occur.
The larger of these convections will result in
the movement of the plates