Restless Earth - Unit 1

Plate Margins
1. Destructive Plate Margin - The oceanic plate moves towards the continental plate, then it subducts underneath the continental plate and causes an earthquake
2. Constructive Plate Margin - The plates move apart, then magma rises between the plates and form volcanoes.
3. Conservative Plate Margin - The plate move sideway and slide past each other. And as it goes at different speeds, and some tend to get stuck then pressure builds up and causes an earthquake
Volcanoes and earthquakes occur near plate margins
Fold mountains - large mountain ranges where rock layers have been crumpled as they have been forced together
Ocean Trenches - deep sections of the ocean, usually where an oceanic plate is sinking below a continental plate
The Earth has: a solid inner core, a liquid outer core, a liquid mantle and a thin solid crust.
Molten rock, called magma can rise up and out of volcanoes
Composite and Shield Volcanoes
1. Shield Volcanoes: Occur at constructive plate margins, low rounded peak, wide base and gentle slopes, layers of runny lava with little ash and eruptions frequent and non-violent
2. Composite Volcanoes: Occur at destructive plate margins, steep slopes and narrow base, secondary cones layers of thick lava and ash and eruptions infrequent but often violent
How do people use an area of fold mountains?
1. The Andes is a range of young mountains formed some 65 million years ago, it used for farming, mining, hydroelectric power and tourism
Subsistence - Farming to provide food and other resources for the farmer's own family
Terraces - Steps cut into hillsides to create areas of flat land.
Irrigation - Artificial watering of the land
Case Study for Volcanoes: Nyiragongo, Africa and Mt St Helens, USA
Monitoring and Predicting Volcanoes: Tiltmeters detect a change in slope caused by shifting magma beneath the surface
What is a Supervolcano?
1. Supervolcano - a mega colossal volcano that erupts at least 1,000 km3 of material and they are very destructive
  1. Yellowstone, Montana in the USA erupted 630,00 years ago
  2. Supervolcanoes do not look like volcanoes with characteristic cones. Instead, they are large depressions called Calderas.
Earthquake - a sudden and brief period of intense ground shaking.
Richter Scale - a logarithmic scale used for measuring earthquakes, based on scientific recordings of the amount of movement
Volcanoes are extinct, dormant or active
1. Extinct - It will never erupt again e.g. Devil's Tower, Wyoming
2. Dormant - It hasn't erupted in 2000 years e.g. Santorini, Greece
3. Active - It has erupted recently and is likely to erupt again e.g. Mt.Etna, Sicily
Calderas - depression of a supervolcano marking collapsed magma chamber
Earthquake - a sudden and brief period of intense ground shaking
Focus - the point in the Earth's crust where the earthquake originates.
Epicentre - the point at the Earth's surface directly above the focus.
To measure an earthquake use a: Seismogram
Earthquake's occur at destructive plate margins and constructive plate margins.
Case Study for an Earthquake is Kobe, Japan and Sichuan, China.
The Three Ps: Prediction, Protection and Preparation
Tsunamis : a special type of wave where the entire depth of the sea or ocean is set in motion by an event, often an earthquake, which displaces the water above it and creates a huge wave
Case Study for a Tsunamis is: The Indian Ocean tsunami
Shock waves - seismic waves generated by an earthquake that pass through the Earth's crust.
Mercalli - a means of measuring earthquakes by describing and comparing the damage done, on a scale of I to XII.

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