Geography
Natural Disaster
What is a natural disaster?
A natural disaster is a disaster that is not man-made meaning that nature made it. It is an event that results in terrible damage or lots of death.
What are the factors which affect a hazard risk?
Magnitude
Duration
Location / concentration
Predictability
This can help us prepare if a natural disaster is about to happen meaning that it can give us time to escape or get ready etc. But if we can't predict when a disaster is going to happen then the disaster will be much more serious.
This means how long a disaster lasts, in most cases the longer the more serious but sometimes shorter ones can be more serious as well.
This is how strong a disaster is. Using scales such as the Richter Scale we can measure how strong a disaster is. Stronger = more serious
This is a important factor. This is because hazards are normally located near plate boundaries which can help us prepare but when we can't if the disaster happens near a city/capital then it would be much more serious than one near a tiny village.
Frequency
This means the size of the next hazard/the return of it. Example, earthquakes with a magnitude of 8 can happen once a year but ones with a magnitude of 3 (which is tiny and probably can't feel it) can happen many times a day. Basically the smaller the frequency and bigger the hazard means that it is more severe.
Internal Structure of Earth
Crust
Mantle
Outer core
Inner core
Asthenoshere is part of the mantle and is 80km deep where rocks which are semi-molten stay.
This is the outside layer of the Earth. It is the thinnest layer which is made out of solid rocks and minerals. 40km deep with a temperature of 200°c to 400°c.
The third layer counting in from the earth. It is made out of liquid and mostly made up of iron, due to the iron the earth has a magnetic field. Temperature is 4500°c.
Its a dense ball of extremely hot iron. The pressure is insane meaning that it cant turn into a liquid. Radius is about 1220km. Its 6000°c hot.
Two types of plates are located on the crust, Oceanic and Continental.
The mantle is the thickest layer of the earth. 2900km thick with a temperature of 1000°c to 3700°c. Lava can come from the upper part of the mantle, which gets to the surface through a volcano. The inner heat can set up convection currents in the mantle.
Plate boundries
Constructive (divergent)
This is when the continental plates move away from each other. The magma then forces the ends of the plates to move up making a dome shape which is called ridges. The magma then is squeezed into the gap which forms new land.
Destructive (subduction)
This is when an oceanic plate (denser and newer) moves towards and below a continental plate (less dense and older). This can form a deep-sea trench. The oceanic plate is then melted by the friction which the magma then flows through the fault lines to form volcanoes. The subduction zone (when they lock and release) can also cause earthquakes.
Destructive (collision)
The two continental plates moves towards each other which then makes the plates crumple upwards to form fold mountains.
Conservative
This is when two continental plates either move past or the same way. The plates can sometimes stick together which can cause tension to form and when this tension is released, an earthquake can occur, the longer the tension is there the larger the earthquake.
Key terms of a earthquake
Epicenter - the point right above the focus, where most of the shaking happens
Focus - the point where the tectonic plates release.
Seismic waves- waves which are passed through the ground which causes it to shake
Fault line - the area where the rocks along the tectonic plates are the weakest.
How are earthquakes measured?
Richter scale
A Richter scales is a logarithmic scale meaning that it goes up in factors, for e.g. a 1 can equal to 10 a 2 equals to 20 a 3 equals to 30. This shows that it is 10 times stronger each unit it goes up in.
Seismic waves
Surface waves- On the surface of the earth like ripples on water.
Body waves- travels though the earths inner layers
Effects and responses
Responses
Short term - this is the response like right after or a few days after, e.g. saving people, giving food out, search and rescue.
Long term - a response which goes on for months and sometimes years, e.g. rebuilding buildings, supplying food/water and reconstructing roads.
Effects
Primary - Is like the actual disaster, e.g. earthquake, the ground is shaking, volcano, buildings collapse
Secondary - What happens right after the primary effect, e.g. gas pipes ruptured because of earthquake, people die, no medic coming through as roads are damaged
Whats the difference between poor and wealthy countries?
First of all, they have more money. This means a lot of stuff such as better buildings, responses (food, shelter, help, medic), less chance of dying. But a poor country is the exact opposite.
If we compare Haiti and the UK we can see a huge difference.
Life expectancy - Haiti - 63 years England - 82 years
GPD - Haiti $810 UK - £39,100
Huge differnce, this can mean lots of things such as the location, maybe there are lots of natural disasters or hazards there, or maybe the money, no medical help or maybe not enough food or shelter.