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hazardous environment (Volcano-an opening in the earth’s crust through…
hazardous environment
Volcano-an opening in the earth’s crust through with hot molten magma, molten rocks and ashes can be able to reach the ground surface.
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measured by the volcanic explosivity index, The index is based on a rate of 1 to 8, 1 means very small and 8 mean s very huge.
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States of volcano
Extinct: a volcano that can never erupt again, or not erupted in 10,000 years. It’s not expected to erupt again as there’s no longer a source of magma.
Dormant: a volcano that has erupted in the last 10,000 years, but has not been seen activity for the last 400 years(in the recent past) and still has the ability to erupt.
Active: a volcano that has erupted recently, or is continuously erupting. It’s expected to erupt again.
During the eruption
Lava flows: since lava flows reach much beyond 10 km from the volcanic crater, they don’t cause as much death and destruction as you may think. Lava flows may destroy farmland, buildings and lines of transport, but lives are rarely lost.
Gas emissions: sulphur gases are not the only type emitted during an eruption, other gases emitted, notably carbon dioxide and cyanide, can also kill. Being dense, they keep close to the ground. Particularly lethal are what are known as pyroclastic flows.
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Pyroclastic flow: dense cloud of gas and ash collapse to the surface, moves quick(600 mph)
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Tsunamis: mud, ash flows and landslides can create large waves if they enter water quickly. Tsunamis can cause large losses of life and destruction to property in coastal areas.
Inside the volcano
Magma chamber: a collection of magma inside the earth, below the volcano.
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types of volcanoes
shield
built from low viscosity basalt lavas that flow long distances out of a central vent building a broad, gently sloping cone.
cinder cone
Made of cinders, no lava. Tall and steep. Occur in groups.
composite
Found at destructive plate boundaries. They have very violent eruptions. Lahars(mudflows) can happen when rainwater mix with ash. The lava escapes through a number of vents and parasitic cones. This viscous lava moves more slowly. There are also steep sides. The volcanoes are made up of layers of ash and lava.
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Plate boundaries
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Collision
When 2 continental plates collide due to they are of equal density, neither sinks or is subducted.
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Hurricanes
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measured by Saffir Simpson scale, using wind speed in miles per hour(mph)
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Hurricane Katrina
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Where: South America, New Orlean(Mexico)
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