Natural Hazards

• Crust


  The solid surface of the Earth
• Plate


  A huge section of the Earth's crust
• Plate margin


  The edge or boundary between two plates
• Mantle


  The layer of semi-molten rock below the Earth's crust
• Convection currents


  The circular movement of magma in the mantle due to the heat from the core
• Subduction zone


  The area where the oceanic plate sinks under the continental plate
• Conservative margin


  Two plates move side by side, neither is subducted (e.g. San Andreas fault, California)
• Constructive margin


  Two plates move apart (e.g. Mid-Atlantic ridge)
• Destructive margin


  Where oceanic plate goes under continental plate (e.g. West coast of South America)
• Collision zone


  Where two continental plates move towards each other, causing the rocks to buckle
• Fold mountain


  Mountains formed by plate movements (e.g. Himalayas, Asia)
• Oceanic trench


  Deep sections of the oceans, usually where oceanic plate is sinking below continental plate
• Composite volcano


  Steep-sided cone with layers of ash and lava (e.g. Vesuvius, Italy)
• Shield volcano


  Gently sloping sides, wide base, made of basic lava (e.g Mauna Loa, Hawaii)
• Subsistence farming


  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 (often using sprinklers)
• Hydro-electric power (HEP)


  Using flowing water to turn turbines to generate electricity
• Natural hazard


  An event in nature that causes harm to the people and their surroundings
• Primary effects


  The immediate effects or the event, caused directly by it, (e.g. water pipes burst)
• Secondary effects


  The after-effects that occur as an indirect effect of the event (e.g. fire)
• Aid


  Help
• Earthquake


  A shaking of the Earth's crust
• Immediate response


  How people react as the disaster happens and straight afterwards
• Long-term response


  Later reactions that occur in the weeks, months and years after the event
• Crater


  The opening at the top of a volcano from which magma is emitted
• Lahar


  Mudflow after a volcanic eruption formed by ash mixing with water or melting ice
• Supervolcano


  A mega colossal volcano that erupts at least 1,000km3 of material
• Caldera


  A depression within a volcano showing a collapsed magma chamber
• Fissures


  Extended openings along a line of weakness that allow magma to escape
• Geothermal


  Water that is heated beneath the ground by the heat of the Earth
• Geosyncline


  A depression in the Earth's surface (such as an ocean or large lake) in which sediments are deposited.
• Hot spot


  A section of the Earth's crust where plumes of magma rise, weakening the crust. Away from plate boundaries, (e.g. Hawaii)
• Focus


  The point in the Earth's crust where the earthquake takes place
• Richter scale


  Measures the strength (force of the earthquake)
• Epicenter


  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


  Measures an earthquake by looking at the damage done on a scale of 1-12
• The three Ps


  Prediction, protection and preparation
• Lava


  Molten rock above the Earth's crust