Download Plate Tectonics and Associated Hazards

Plate Tectonics and
Associated Hazards
Unit 3
Section 1 : Plate Movement
 Structure of the Earth
Tectonic Theory
Plate Margins
Hot Spots
Section 2: Vulcanicity
 Volcanic Activity
 Major forms of Extrusive activity
Minor forms of Extrusive activity
Case study MEDC
 Case study LEDC
Section 3 : Seismicity
 Earthquake Activity
 Tsunamis
Case study MEDC
 Case study LEDC
Brainstorm!
What do you already know about
Tectonics?
Use the overview sheet as a starting point.
Tectonics
Section 1 : Plate Movement
Structure of the Earth
Key Questions:
 What is the structure of the Earth?
What are the properties of the
different layers?
High temperatures near the core are
believed to be responsible for the
generation of convection currents.
Approximately the size of Mars.
Thinnest, coolest and least dense layer.
Varies in thickness from 5 to 70 km.
Most of the mantle (asthenosphere) acts like it is semimolten.
Separated from the mantle by the
Mohorovijic (Moho) discontinuity.
Surrounded by semi-molten outer core.
Temperature over 6000˚C.
The most dense part of the planet.
Made up of rocks rich in iron and nickel.
The inner core is solid.
Separated from the core by the Gutenburg discontinuity.
Starts about 2900km down.
Rocks are rich in silicon, oxygen,
aluminium, potassium and sodium
Temperatures near the core reach 5000˚C.
Centre is 6350km down.
Largely composed of silicate rocks rich in iron and magnesium.
Upper mantle (close to the crust) is rigid and together with the crust forms the
LITHOSPHERE.
The Core
• Approximately the size of Mars
• Starts about 2900km down
• Centre is 6350 km down
• The most dense part of the planet
• Made up of rocks rich in iron and nickel
• Core temperature over 6000oC
• Outer core is semi-molten/liquid (only part of the planet which is!)
• Inner core is solid
The Mantle
• Separated from the core by the Gutenburg discontinuity
• Largely composed of silicate rocks rich in iron and magnesium
• Upper mantle (close to the crust) is rigid and together with the crust forms the lithosphere
• Most of the mantle (asthenosphere) acts like it is semi-motlen.
• Temperatures near the core reach 5000oC
• High temperatures near the core are believed to be responsible for the generation of
convection currents.
The Crust
• Thinnest, coolest and least dense layer.
• Rocks are rich in silicon, oxygen, aluminium, potassium and sodium
• Separated from the mantle by the Mohorovijic (Moho) discontinuity.
• Varies in thickness from 5 to 70 km
Some very important terms:
Lithosphere: consists of the crust and the
rigid upper section of the mantle,
approximately 80-90km thick. Divided
into seven large plates and a number of
smaller ones.
Asthenosphere: the semi-molten mass
below the lithosphere on which the plates
float and move. Beneath the
asthenosphere is the rest of the mantle,
which is completely solid.
• What are the names for the two types of
crust that form the lithosphere?
• Use the text book to complete your own
table like this one:
Thickness
Age
Density
Composition
Continental
crust
Oceanic crust
Think about a Ferrero Rocher
This outer layer hold the liquid chocolate
in, it’s the C. . . . .
These nutty flakes float on the C. . . . Like
P. . . . . .
This liquid chocolate centre is like
the M . . . . .
Solid on the outside the central nut is just
like the C . . .
Evidence can be found lying on the
Earth's surface. Occasionally rocks
from deep inside the Earth's core are
brought to the surface where they are
collected and studied.
How do we know all of this?
Measurements of energy waves that pass
through the Earth can be measured very
accurately and at huge distances. They travel at
different speeds through different materials.
Scientists can translate this information into an
accurate picture of the Earth's structure.
Homework
Start creating an electronic glossary for this
unit – useful for revision.
Key terms from today:
Inner core
Outer core
Mantle
Crust
Lithosphere
Asthenosphere
Oceanic crust
Continental crust
Plenary squares.
• Current seismic activity
• http://www.iris.washington.edu/seismon/