Post on 02-Jan-2016
Earth Hazards Revision –Level 5
1. Map showing where volcanoes and earthquakes happen
Mid-Ocean Ridges
Pacific Ring of Fire
MediterraneanMediterranean to Indonesia
Andes Mts
Earthquake lines
Volcanoes
5C Describe and explain the effects of a volcano on nearby villages.
• Dust clouds from the volcano block the sunlight
• So the village gets as dark as nighttime.
• Ash falls all round the volcano
• So houses collapse and roads are blocked to vehicles.
• Lava flows down to the village so homes are buried or burned..
Case study – Italy’s Mt. Etna
5C What is deforestation.
• Deforestation means “cutting down trees”.
The word comes from:-
• De (doing away with)
- forest (area of many trees)
- ation ( the process)
5B Describe and explain why deforestation causes soil erosion.
• Soil erosion means that soil has had most of its cover of trees removed.
• Then the soil is easily blown away by wind or washed away by streams.
This soil has been washed away
leaving a gully
5A Describe and explain why deforestation causes soil erosion.
• A cover of trees usually protects the soil.
• If trees are cut down soil is exposed to rain and wind.
• Rainwater then washes away topsoil into rivers, leaving little valleys (called gullies) in the soil
• Then the extra mud in rivers clogs them up and causes floods.
• Because the sandy subsoil is now exposed, strong winds can blow it away to create sand dunes.)
• Sand dunes can cover valuable farmland.
• The soil left behind is useless
•Because it is soil which is moved the processes are called soil erosion.
5A Why Soil Erosion is a Hazard.
• Because the soil is loose, heavy rain can cause mudflows which cover homes and can kill people.
• Even when rainwater washes away topsoil gently into rivers, the extra mud forms mudbanks.
• Because of this navigation becomes difficult for ships.
• Because of the mudbanks, rivers flood more deeply, destroying more farmland..
• Because sand dunes creep forward in the wind, valuable farmland may be covered and destroyed.