Plate Tectonics Revision 6 th year Geography Learning

Plate Tectonics Revision 6 th 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 • • Collision of plates Subduction Volcanoes Eg; Mount Saint Helens Fold Mountains Eg; Alps Earthquakes Eg; Kobe

Constructive Plate Boundaries • • • Plates separate Rift Valley Eg; African Rift Valley Mid Ocean Ridges Eg; Mid Atlantic Ridge

Conservative Plate Boundaries • • • Plates slide past each other Earthquakes Eg; Haiti 2010 Transform fault Eg; San Andreas Fault

Exam Questions – Plate Tectonics • Explain how 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 • • 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 • • • 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 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 • Volcanoes can have an example you have both positive and studied why volcanic negative effects. activity happens at Examine the effects of a plate margins. volcano that you have studied. • Explain how the study of plate tectonics has helped us to understand the global distribution of volcanoes.