Plate Tectonics Revision
6th year Geography
Learning Outcome
• Revise Core Book
– Chapters 1 – 3
– Plate Tectonics
– Earthquakes
– Volcanoes
– Examine the exam questions on these topics
Theory of Plate Tectonics
• Earths plates move
• Landforms result
Tectonic Cycle
• Continuous destruction and formation of the
earth’s crust at plate boundaries.
Theory of Plate Tectonics
• Wegener 1912
– Continental Drift
• Hess
– Sea Floor Spreading
Destructive Plate Boundaries
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Collision of plates
Subduction
Volcanoes
Eg; Mount Saint Helens
Fold Mountains
Eg; Alps
Earthquakes
Eg; Kobe
Constructive Plate Boundaries
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Plates separate
Rift Valley
Eg; African Rift Valley
Mid Ocean Ridges
Eg; Mid Atlantic Ridge
Conservative Plate Boundaries
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Plates slide past each other
Earthquakes
Eg; Haiti 2010
Transform fault
Eg; San Andreas Fault
Exam Questions – Plate Tectonics
• Explain how the theory of plate tectonics has
aided our understanding of the occurrence of
volcanic activity.
• ‘Plate boundaries are zones where crust is
both created and destroyed.’ Examine the
above statement with reference to examples
you have studied.
Earthquakes
• Focus
• Tremor
• Epicentre
Measuring Earthquakes
• Seismographs (record earthquake waves)
• Richter Scale (energy / magnitude)
• Modified Mercalli Scale (damage seen)
Effects
Short Term
• Death
• Destruction
• Tsunamis
• Fire
• Homelessness
Long Term
• Migration
• Disease
• Economic slowdown
Case Study
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South East Asian Earthquake and Tsunami
December 2004
9.0 Richter Scale
Indian Plate slid beneath Burma Plate
Affected 11 countries
320,000 deaths
1.5 million people displaced
Exam Questions - Earthquakes
• Examine how earthquakes are measured and
may be predicted.
• Describe and explain an earthquake that you
have studied under the following headings;
– Plates involved
– What caused the earthquake
– Long & Short Term Effects
– Recovery
Volcanoes
Volcanoes occur at...
• Mid-Ocean Ridges (Constructive Plate
Boundaries)
• Subduction Zones (Destructive Plate
Boundaries)
• Hotspots
Products of Volcanic Eruptions
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Lava
Pyroclasts
Poisonous gases
Ash, pumice, dust
Water vapour
Volcanic Landforms
External
• Lava Plateau
• Volcanic cones
• Craters
• Calderas
• Volcanic plugs
Internal
• Batholiths
• Sills
• Dykes
• Laccoliths
• Lopoliths
Effects of Volcanoes
Positive
• New land (Iceland)
• Geothermal energy
• Fertile soil
• Tourism
Negative
• Lava flows destroy and kill
• Lahars destroy and kill
• Poisonous gases harm
health and kill
• Ash can disrupt air travel
Case Study
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Soufriere Hills, Montserrat, Carribbean.
Dormant for 300 years
Active since 1995
June 1997- 9 people killed, 100 homes
destroyed.
• Pyroclastic flow 160 kmph
• 24 hour monitoring- Montserrat Volcano
Observatory
Exam Questions
• Explain with the aid of
an example you have
studied why volcanic
activity happens at
plate margins.
• Explain how the study
of plate tectonics has
helped us to
understand the global
distribution of
volcanoes.
• Volcanoes can have
both positive and
negative effects.
Examine the effects of a
volcano that you have
studied.