Natural hazards Flashcards
What is a natural hazard?
A natural event that threatens people of has the potential to cause damage, destruction and death
What are the 4 different categories of hazard?
Atmospheric, geological, water based, biological
Give some physical factors affecting hazards
Magnitude, geology, level of development of the place,
Give some human factors affecting hazard risk
Population density, governments, technology
What four parts is the earth made up of?
Inner core, outer core, mantle, crust
Inside the earth, heat is released from the core which creates convection currents in where?
The mantle
Which crust is more dense: oceanic or continental ?
Oceanic
Describe the pattern of earthquakes
Generally, earthquakes are found on the plate boundaries. For example, the Nazca and South American plate boundary is a destructive plate boundary.
Describe the pattern of volcanoes
Volcanoes are usually found on constructive and destructive plate boundaries. For example, Iceland is ok the constructive plate boundary and there are usually a lot of volcanoes there.
Why do earthquakes and volcanoes mainly occur along plate margins?
Because they are caused by the friction between the two plates or the hot molten rock(magma) rising to the surface of the earth
What is an epicentre?
It’s directly above the focus. It’s where the seismic waves are the strongest. The epicentre has the most potential for damage
What is a focus?
The point at which the earthquake is occuring
Why might there not be any damage at the epicentre of an earthquake?
There might be nothing there, for example, there might only be vegetation in the area
Describe what happens at a destructive plate margin
-Oceanic and continental plate are moving towards each other
-Oceanic plate is subducted
Describe what happens at a constructive plate margin
Two plates move apart
Describe what happens at a conservative plate margin
Two plates slide past each other
What were the primary and secondary effects of the Nepal earthquake(case study)
PRIMARY-9000 people died, 20,000 injured, 3million left homeless
SECONDARY-ground shaking triggered landslides and avalanches, avalanches on Mt. Everest killed at least 19 people
What were the primary and secondary responses of the Nepal Earthquake(case study)
PRIMARY- The Red Cross set up temporary shelters for 225000 people, the UK raised US$125 million to provide emergency aid
SECONDARY-thousands of homes were repaired, stricter building controls in the future
What were the primary and secondary effects from the earthquake in l’Aquila.
PRIMARY- 300 people died, 1,500 injured, 67000 made homeless
SECONDARY-house prices and rent increased due to lack of housing, business and tourism had suffered as there are still unsafe buildings in the city centre
what were the primary and secondary responses from the earthquake in l’Aquila?
PRIMARY-hotels provided shelter for 10,000 people and 40,000 tents were given out, the EU gave US$552 million to help rebuild l’Aquila
SECONDARY-residents didn’t have to pay tax for 1 year, free public transport for students
What ECONOMIC reasons would people continue to live in areas at risk from tectonic hazard?
- poor people can not afford to live anywhere away from volcanoes as the e provide jobs
-better job opportunities
What SOCIAL reasons would people continue to live in areas at risk from tectonic hazard?
-the hazards are predictable
-some people are well prepared for hazards so people feel safe
What ENVIRONMENTAL reasons would people continue to live in areas at risk from tectonic hazard?
-fertile soil
-Iceland volcanoes provide cheap geothermal power
What conditions come with high pressure?
Sunny, warm, clear skies
What conditions come with low pressure?
Wet, rainy, cloudy
Describe the global distribution of tropical storms
-They occur between the Tropic of Cancer and the Tropic of Capricorn
-There aren’t any tropical storms on the equator
-We don’t tend to get tropical storms in the south Atlantic Ocean
What conditions are needed from a tropical storm to form?
Ocean-27 degrees Celsius
During summer and autumn time
Between 8-20 degrees north and south of the equator
Over how many years does an axial tilt happen?
41,000
Over how many years does eccentricity happen?
100,000
Over how many years does precession occur?
26000
Give some mitigation strategies
-alternative energy sources
-carbon capture
-planting trees
-international agreements
Give some adaptation strategies
-adapting farming methods
-managing water supplies
-reducing risk from rising sea levels
What are interglacials and how long do they last for?
Warm periods- approximately 10000 years
What are glacials and how long do they last for?
Cold periods- approximately 100,000 years
When did the last cold period end
About 12,000 years ago
What are the 4 evidences for climate change
Ice cores
Rising sea levels
Tree rings
Shrinking glaciers
