The Challenge of Natural Hazards Flashcards
What is a natural hazard?
A natural process which could cause death, injury and disruption to humans
What is a geological hazard?
A hazard caused by land and tectonic processes
Name one example of a geological hazard
Volcanoes, earthquakes, landslides or avalanches
What is a meteorological hazard?
A hazard that is caused by weather and climate
Name on example of a meteorological hazard
Tropical storms, droughts, cold spells or climate change
What factors increase the risk of being affected by a natural hazard?
Densely populated areas
Low income so lack of knowledge or protection
Severity of the event eg a powerful earthquake
Name the four parts to the structure of the earth
Crust, mantle, outer core, inner core
What is the difference between continental crust and oceanic crust?
Continental crust is thicker (30-50km) and less dense. Oceanic crust is thinner (5-10km) and more dense.
Describe what happens on a destructive plate margin
- Two plates are moving towards each other
- The denser oceanic plate is forced underneath continental plate.
- As it is forced down the friction causes the oceanic plate to melt.
- As the magma rises back up to the surface a volcano is created.
- Fold mountains are also created as the land is crumpled when the two plates collide.
- An ocean trench is created where the oceanic plate is being pulled down.
A good example is the Nazca and the South American plate.
Describe what happens on a constructive plate margin
- Two plates are moving away from each other
- Magma (molten rock) rises from the mantle to fill the gap.
- As this cools it creates new crust
A good example is Iceland on the Mid Atlantic ridge
Describe what happens on a conservative plate margin
- Two plates are moving sideways past each other or in the same direction but at a different rate
- Where the plates edges are jagged, they get stuck. Pressure builds up and is eventually released as an earthquake.
The San Andreas fault line in west coast of the USA is a good example
What plate margin does not lead to the creation of a volcano?
Conservative
Which plate margin is more violent?
Destructive
Which type of earthquake is more severe - shallow focus or deep focus?
Shallow focus. This means the plate movement has happened closer to the ground surface. This leads to more damage on the earth surface.
What is the epicentre?
The point directly above the focus of the earthquake
How are earthquakes measured?
On the Richter Scale.
How does the Richter scale work?
It is a logarithmic scale so each step up on the Richter scale is 10x worse than the one before so a 6 is 10 times worse than a 5. There is also no upper limit but the highest recorded is a 9.1 in Alaska.
Name the primary effects of an earthquake
Building collapse; Injury and death to people through the collapsed buildings or falling debris; Infrastructure (roads, railways, ports and airports) damaged; electricity cables; gas and water pipes and communication networks are damaged, cutting off supplies.
Name the secondary effects of an earthquake
Landslides; tsunamis; fires caused by leaking pipes; homelessness; shortage of clean water so disease can spread; emergency aid struggles to get through as roads are blocked; unemployment as businesses including the tourist industry are affected; high cost of repairs damaging the economy of the country.
What are the immediate responses to an earthquake?
Rescue trapped people; recover dead bodies to prevent the spread of disease; put out fires; set up temporary shelters; provide temporary supplies of water, food, gas and electricity; foreign governments and charities may send aid.
What are the long term responses to an earthquake?
Rehouse people who have lost their homes; repair and rebuild buildings and roads; reconnect broken electricity, water and gas pipes; improve building regulations; set up initiatives to improve economy and boost tourism.
When was the Chile earthquake?
February 2010
What was the Chile earthquake on the Richter scale?
Magnitude 8.8
How many people died in the Chilean earthquake?
500 people
How many people were injured in the Chilean earthquake?
12,000 people
How much did the Chilean earthquake cost?
$30 billion