Volcanoes
- Created by: Rachelezy
- Created on: 10-10-18 13:06
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- Volcanoes
- Basic Information
- Earth's crust through which lava, ash and gases erupt.
- Closely associated with plate margins
- Hot magma and gases push up from mantle to the Earth's crust
- Lava = Magma that reaches the Earth's surface
- Around 1900 volcanoes are considered to be active
- Primary Hazards
- Lava Flows
- Streams of lava
- Have erupted from a volcano onto the Earth's surface
- Takes years to cool completeley
- Move slowly - Not very threatening to humans
- Destroy everything in their path
- Pyroclastic Flows
- One of the greatest volcanic hazards
- Mixture of dense hot rock, lava. ash, and gases ejected from a volcano
- Destroy everything in their path
- Move very quickly and can reach up to 700'C
- Can travel at 100 km per hour
- Tephra and Ash falls
- Tephra -Pieces of volcano rock and ash which blast into air during an eruption
- Larger pieces tend to fall near the volcano
- Can cause injury and death (as well as damaging structures)
- Ash falls - Very disruptive
- Covers everything causing poor visibility and slippery roads
- Roofs may collapse due to its weight
- Engines may get clogged or stop working
- Gas Eruptions
- Released into atmosphere during eruption
- Potential hazard to people, animals and structures
- Water Vapour (80%)
- Carbon Dioxide
- Sulphur Dioxide
- Can travel for thousands of kilometres
- Released into atmosphere during eruption
- Lava Flows
- Secondary Hazards
- Lahars
- Masses of rock, mud and water that travel quickly down the side of a volcano
- Travel too fast for people to outrun
- Caused when an eruption quickly melts snow and ice
- Or heavy rainfall during or after and eruption
- Jokulhlaup
- Glacial outburst floods
- Dangerous because they suddenly release large amounts of water, rock, gravel and ice that can catch people unaware.
- Flood and damage land and alnd structures
- Heavy and sudden floods made by an eruption melting ice and snow in a glacier
- Lahars
- Basic Information
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