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DISTRIBUTION AND TRENDS - Coggle Diagram
DISTRIBUTION AND TRENDS
DISTRIBUTION
PLATE BOUNDARIES Geophysical hazards occur near plate boundaries. These plates move at different speeds and directions which can cause collisions, earthquakes and volcanic activity as shown in the map above.
INTRA PLATE Earthquakes can also occur near the middle of plates (called intra-plate). The causes of this are not fully understood but it is assumed that plates have pre-existing weaknesses which become reactivated, forming seismic waves. For example, an intraplate earthquake may occur if solid crust, which has weakened over time, cracks under pressure.
VOLCANIC HOTSPOTS
such as the Ring of Fire, are also situated amongst the centre of pates. This is a localised area of the lithosphere (Earth’s crust and upper mantle) which has an unusually high temperature due to the upwelling of hot molten material from the core. (First theorised by Tuzo Wilson in 1963)
HOTSPOTS s, such as the Hawaii hotspot, magma rises as plume (hot rock).
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OCEANIC FRACTURE ZONE OFZ – This is a belt of activity through the oceans and along the mid-ocean ridges through Africa, the Red Sea, the Dead Sea
CONTINENTAL FRACTURE ZONE CFZ – This is a belt of activity along the mountain ranges from Spain through the Alps to the Middle East and to the Himalayas.
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NATURAL HAZARD can be either hydro-meteorological (caused by climatic processes) or geophysical (caused by land processes).
TRENDS
SINCE 1960
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The number of fatalities has decreased, but there are some spikes during mega disaters
The total number of people being affected by tectonic hazards is increasing, due to population growth
The economic costs associated with hazards and disasters has increased significantly. This is partly due to increases in development as infrastructure in more developed countries costs more to repair. Also, increasing number of insurance policies, especially in developed countries, heightens the costs.
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