A natural hazard becomes a disaster when at least one of the following criteria are met: 10+ people are killed. 100+ people are affected. A state of emergency is declared. International assistance is called for.
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Primary and Secondary effects of Natural Hazards?
Primary Effects occur as a direct result of the incident, e.g. Burst water pipes, collapsed buildings. Secondary Effects occur as a result of the primary effects, e.g. Disease, starvation
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Factors affecting Hazard Risk?
Human: Level of Preperation, Level of Development, Population density, Building/Infrastructure, Type of Governance. Physical: Magnitude/frequancy of hazard, Location of Hazard, Time of Day, Type of Hazard
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Distribution of Tectonic Hazards?
All Tectonic Hazards are located near plate margins, and there are dense clusters on the Pacific Ring of Fire, and the Mid-Atlantic Ridge.
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Hot Spots?
Hot spots are places within the mantle where rocks melt to generate magma.Mantle plumes are areas of hot, upwelling mantle. A hot spot develops above the plume. Magma generated by the hot spot rises through the plates and produces an active Volcanoe.
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The Crust?
The crust is the outer layer of the earth. It is a thin layer between 0-60km thick. The crust is the solid rock layer upon which we live. There are two different types of crust: continental crust and Oceanic Crust.
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The Mantel?
The mantle is the widest section of the earth. It has a diameter of approximately 2900km. The mantle is made up of semi-molten rock called magma.
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The Inner Core?
The inner core is in the centre of the earth and is the hottest part of the earth. The inner core is solid. It is made up of iron and nickel with temperatures of up to 5500°C.
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The Outer Core?
The outer core is the layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel. It is still extremely hot here, with temperatures similar to the inner core.
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Constructive Plate Boundaries?
At a constructive plate boundary, two oceanic plates move apart. As the two plates move apart, magma (molten rock) rises up to fill the gap as volcanoes. Magma can escape easily so there are no violent eruptions. E.g. Mid-Atlantic Ridge.
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Destructive Plate Boundaries?
Denser Oceanic and Continental plates move towards each other. In subduction zone, Oceanic plate forced under continental plate, melts to magma, which forms a magma chamber, earthquakes triggered. Magma rises through cracks. Eruptions can be caused
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