Restless Earth Glossary

Question	Answer
Crust	The outer layer of the earth
Plate	A section of the earth's crust
Plate Margin	The boundary where two plates meet
Mantle	The dense, mostly solid layer between the outer core and the crust
Convection currents	The circular currents of heat in the mantle
Subduction	The sinking of oceanic crust at a destructive margin
Collision	The meeting of two plates of continental crust. They are both the same type so they meet ‘head on’ and buckle
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
Composite volcano	A steep-sided volcano that is made up of a variety of materials, such as lava and ash
Shield volcano	A broad volcano this is mostly made up of lava
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
Hydroelectric power	The use of flowing water to turn turbines to generate electricity
Natural hazard	An occurrence over which people have little control, which poses a threat to people’s lives and possessions. This is different from a natural event as volcanoes can erupt in unpopulated areas without being a hazard
Primary effects	The immediate effects of the eruption, caused directly by it
Secondary effects	The after-effects that occur as an indirect effect of the eruption on a longer timetable
Aid	Money, food, training and technology given by richer countries to help poorer ones, either to help with an emergency or to encourage long-term development
Earthquake	A sudden and often violent shift in the rocks forming the earth’s crust, which is felt at the surface
Immediate responses	How people react as the disaster happens and in the immediate aftermath
Long-term responses	Later reactions that occur in the weeks, months and years after the event
Vent	The opening – usually central and single – in a volcano, from which magma is emitted
Lahar	These secondary effects of a volcanic eruption are mudflows resulting from ash mixing with melting ice or water
Supervolcano	A mega colossal volcano that erupts at least 1,000km3 of material
Caldera	The depression of the supervolcano marking the collapsed magma chamber
Fissures	Extended openings along a line of weakness that allow magma to escape
Geothermal	Water that is heated beneath the ground, which comes to the surface in a variety of ways
Geyser	A geothermal feature in which water erupts into the air under pressure
Hot spot	A section of the earth’s crust where plumes of magma rise weakening the crust. These are away from plate boundaries
Earthquake	A sudden and brief period of intense ground shaking
Focus	The point in the earth’s crust where the earthquake originates
Richter Scale	A logarithmic scale used for measuring earthquakes, based on scientific recordings of the amount of movement
Epicentre	The point at the earth’s surface directly above the focus
Shock waves	Seismic waves generated by an earthquake that pass through the earth’s crust
Mercalli scale	A means of measuring earthquakes by describing and comparing the damage done, on a scale of I to XII
Debt	Money owed to others, to a bank or to a global organisation such as the World Bank
The three Ps	The collective term for prediction, protection and preparation
Prediction	Attempts to forecast an event – where and when it will happen – based on current knowledge
Protection	Constructing buildings so that they are safe to live in and will not collapse
Preparation	Organising activities and drills so that people know what to do in event of an earthquake
Tsunami	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

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Restless Earth Glossary

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	Created by Clare Magor almost 10 years ago