Natural Hazards

hannah.pickard
Mind Map by , created over 6 years ago

Higher Geography (Natural Hazards) Mind Map on Natural Hazards, created by hannah.pickard on 05/07/2013.

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hannah.pickard
Created by hannah.pickard over 6 years ago
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Natural Hazards
1 Tectonic Hazards
1.1 Volcanoes
1.1.1 Composite
1.1.1.1 Pyroclastic flow

Annotations:

  • A destructive flow of hot ash, rocks, gases and steam that can travel at speeds of up to 200mph.
1.1.1.2 Ash cloud

Annotations:

  • Causes suffocation and leads to many health problems
1.1.1.3 Lahar

Annotations:

  • Mudslide made of melted snow and volcanic ash
1.1.1.4 Sticky acidic lava escapes form the main and side vents

Annotations:

  • Magma is also viscous
1.1.1.5 Ash erupts before lava, so they are made of alternate layers.
1.1.1.6 Found at destructive boundaries
1.1.2 Shield
1.1.2.1 Found at constructive boundaries
1.1.2.2 Eruptions surface basic lava, which forms wide sides and gradual slopes .

Annotations:

  • Basic lava - runny lava that flows quickly and a long way before it cools
1.1.2.3 Eruptions are not explosive because magma is not viscous

Annotations:

  • Viscous lava traps hot gases, the pressure builds and gases are suddenly released in explsove eruptions. 
1.2 Plate Boundaries
1.2.1 The Earth's crust is seperated into different plates
1.2.1.1 The main ones
1.2.1.1.1 North and South American plates
1.2.1.1.2 African plate
1.2.1.1.3 Eurasian plate
1.2.1.1.4 Indo-Australian plate
1.2.1.1.5 Caribbean plate
1.2.1.1.6 Pacific plate
1.2.2 Most volcanoes and earthquakes occur at plate boundaries
1.2.3 Types
1.2.3.1 Destructive

Annotations:

  • Denser continental plate subducts oceanic plate, it becomes magma in the mantle. The magma is forces to the surface through volcanoes. The plate also causes friction between the plates which causes earthquakes.
1.2.3.2 Constructive

Annotations:

  • Tectonic plates are moving away from each other, magma rises in the gap or through fissures creating ridges
1.2.3.3 Conservative

Annotations:

  • Two plates moving past each other, or in the same direction at different speeds. They occasionally snag which builds up pressure released in earthquakes.
1.2.3.4 Collision

Annotations:

  • Two continental plates moving towards each other and forcing each other upwards, making fold mountains.
1.3 Earthquakes
1.3.1 Focus

Annotations:

  • The pint underground where the earthquakes occurs
1.3.2 Epicentre

Annotations:

  • The point of the surface directly above the focus, where the quakes and damage will be most severe.
1.3.3 Seismic waves

Annotations:

  • Waves of energy released by the quakes that are measure dby seismographs. These come in the form of P and S waves, P waves are faster and spread out first, the S waves follow and are often more destructive.
1.3.4 Measured from 0-10 on the Richter Scale
1.3.5 After shocks

Annotations:

  • Smaller tremours in the days after the initial quake. They can slow down rescue efforts and cause extra damage.
1.3.6 Earthquakes occur at every type of plate boundary
2 Climatic Hazards
2.1 Tropical Storms
2.1.1 Hurricanes
2.1.1.1 off Africa
2.1.1.2 Caribbean, Mexico, southern USA
2.1.1.3 August to October
2.1.2 how they're formed
2.1.2.1 water 27°C or higher
2.1.2.2 warm, moist air

Annotations:

  • the air rises and condensates which releases huge amounts of energy and makes the storm very powerful
2.1.2.3 in either the Atlantic or the Pacific
2.1.3 move west because easterly winds at equator
2.1.4 lose strength over land

Annotations:

  • this is because the supply from warm water is cut off
2.1.5 characteristics
2.1.5.1 spin anti-clockwise
2.1.5.2 circular in shape
2.1.5.3 life span of 7-14 days
2.1.5.4 eye is caused by descending air

Annotations:

  • low pressure, cloud and no rain in here
2.1.6 Cyclones
2.1.6.1 Indian Sea
2.1.7 Tyhpoons
2.1.7.1 Japan and China
2.2 Drought
2.2.1 long period of weeks, months or years where rainfall is lower than average
2.2.2 caused when changes in the atmosphere mean it doesn't rain much
2.2.3 water supplies are depleted

Annotations:

  • people keep using them but they aren't being replenished by rainfall
2.2.4 high temperatures increase the rate of evaporations

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