Natural disasters
Plate boundaries
Destructive plate boundaries: happens when one plate slides under another, usually occurs between oceanic and continental plates and can cause earthquakes and volcanoes,
Volcanoes
Earthquakes
Volcanoes are classified as active, dormant and extinct
Collision plate boundaries: plates pushing against one another, crust gets folded upwards which forms fold mountains and earthquake can also occur but no volcanoes
Conservative plate boundaries: plates sliding past one another, it can cause earthquakes as parts of the plate can get stuck then lurch free, no volcanoes
Constructive plate boundaries: plates are pulled apart and magma seeps out, this only happens on oceanic plates, small volcanoes or more sea floor can form from the magma
Layers of the earth
Crust: solid, temperature 200-400 c, made up of sedimentary rocks and minerals, 2.79/cm3 thick, 8-65km thick
Mantle: solid at outer mantle, liquid at inner, 1000-3700c, made up of silicate rocks, density is 4.5g/cm3 , 2900km thick
Outer core: liquid, made up of iron and nickel, 4500-5500c, density is12.6-13g/cm3, 2300km thick
Inner core: solid, made up of iron and nickel, 6000c, density is 9.9-12.2, 1250 km thick
Earthquakes are caused by the pressure from tectonic plates, when tectonic plates move they get stuck sometimes and pressure builds
Eventually the pressure is released and huge amounts of energy is sent out causing the surface of the earth to shake violently
Earthquakes usually occurs on plate boundaries although some occurs within the plates itself
Earthquakes are measued by seismometer
Pyramid and symmetrical shapes are safer in an earthquake, cross bracing which means diagonal supports in a x shape to prevent buildings from collapsing, walls with steel bars can also help reduce impacts
There are 2 types of volcanoes, stratovolcanoes and shield volcanoes
A shield volcano is like a shield on the ground, the slope is gentle and the magma is very runny which means it flows fast, it occurs on constructive plate boundaries
A stratovolcanoe is the stereotypical one in our mind, it blews up pretty violently and sends out pyroclastic flows and magma which is very sticky, it forms on destructive plate boundaries
Volcanoes occurs on destructive and constructive boundaries, though it can also form within plates
Volcanoes can provides hot springs, free heating and being a tourist hotspot, volcanic ash also makes the land more fertile
The reason that people doesn't move away from volcanoes are that they are lazy, poor or can't move important things like livestocks away