Natural and weather hazards Flashcards
Define the term “natural hazard”
A naturally occcuring event which potentially endangers human life, the economy and property
What factors can affect a hazard risk?
- Population density: the more people living in an area of impact, the more people which are going to be affected
- Magnitude: the higher tha magnitude is, the more powerful the hazard will be, affecting a larger area of impact
- Location: If you live near the coast, you are at risk to tsunamis and flooding. If you live near any plate boundaries you are at risk to earthquakes and volcano eruptions (if you live near a volcano)
GIve more factors which affect a hazard
- Frequency: the more often a hazard occurs, the more risks people will need to face, but they would have more preparation, but possibly not enough time.
- Climate change: a warmer atmosphere and oceans lead to more intense storms and hurricanes, so areas are more at risk to flooding, or are prone to droughts in drier areas
- Level of development and wealth: If a country is a low income country, they may not have enough resources to predict, plan and prepare for any hazards coming, aswell as protecting people and structures. HICs have enough money to invest in advanced technology which can keep citizens safe and lower the impact of a hazard
What are the 3 / 4 P’s?
Prediction, Planning, Preparation and Protection
How is prediction useful to reduce the risk of a natural hazard?
Using technology and instruments like forecasts and satelites, you can estimate when and where a natural hazard might occur, which gives people enough time to plan and prepare for it
Give a few examples of what equipment / technology you can use to predict a volcanic eruption
- Satellite imaging: They use infrared to measure the surface temperature of an area. If the temperature is high, it could mean that magma is rising to the surface, potentially leading to a volcanic eruption
- Seismic waves: Scientists can use seismic waves to predict a volcanic eruption or earthquake. (High Frequency)
- Ground Deformation: The movement of magma can usually deform the ground above. Scientists measure the tilt of the slope (of the volcano) to see if there is any swelling
Give a few examples of what methods are used to predict an earthquake
- Seisometers: They measure/detect the movements of the ground and draw waves on a piece of paper.
- Animal behaviour: Animals are said to react to an earthquake before the event and well before humans.
- Laser beams: Laser beams are used to detect movements from the plates
Give a few examples of plannining for a natural hazard
-Setting laws
- Setting building codes
- Setting up evacuation plans to reduce the impact of it
Give a few examples of preparing for a natural hazard
- Educating people what to do in an event of a hazard, to help reduce panic and fatalities: Every year on September 1st, Japan has a disaster day.
- Building seawalls
- Building quakeproof structures and buildings.
What is the plate tectonic theory
How the earth is structured and what it is made of: Crust, mantle, outer core and inner core
What are the two types of crust and their features?
Oceanic crust - thinner but denser and is made of basalt rock - semi molten
Continental crust - thicker but less dense and is made of granite rock. They both are fractured into different plates
What happens in the mantle?
Thermal convection
80% volume
What is thermal convection?
When super heated magma rises to the surface, cools down and sinks down to where it is then re-heated. This process is called thermal convection and it is repeated again and again
What are convection currents
Convection currents are the cause for the movement of plates
What happens at:
1) A constructive plate margin
2) A destructive plate margin
3) A conservative plate margin
1) When the plates move away from eachother and magma rises up and out <- ->
2) When the plates move towards eachother -><-
3) When the plates move together / slide past eachother
What happens at subduction zone?
The oceanic plate is subducted underneath the continental plate by convection currents, creating a deep ocean trench. The oceanic plate sinks down into the mantle because of slab pull and it is eventually melted because of friction. The friction between the two plates causes intense pressure to build up, which then gives away releasing energy and shockwaves, causing an earthquake.
Volcano: Magma is collected to create a magma chamber, which then rises up through cracks in the continental crust
What is formed at a subduction zone?
Earthquakes, Volcanic eruptions, ocean trenches and fold mountains (such as the Andes, volcanic islands
Name two plates which move into eachother at a destructive plate margin
- Nazca plate and South American
- Pacific plate and Eurasian plate
Describe the global distribution of volcanoes
Are found at destructive and constructive plate margins, and are grouped in clusters or lines (depending on image given). Placed mainly around the pacific ocean + pacific edge.
Describe the global distribution of Earthquakes
Normally found in long, narrow belts along plate margins/boundaries and the west coast of North and South America
Why do people live in areas at risk from a tectonic hazard?
Volcanos: Geothermal energy can be harnessed which is used to drive turbines in power stations to produce electricity. This provides cheaper electricity costs
The soil around volcanic areas are very fertile and rich in minerals. This is beneficial for farmers as they can produce richa nd healthy harvests.
In General: Tourism - provides new job opportunites eg. Tour guide. Tourists also spend money in the local areas in gift shops etc. which is beneficial for the people living there.
Example: Iceland
Nepal Earthquake case study ~ 2015
CAUSES
7.8 magnitude meaning that it was very powerful and area of impact was large.
Nepal lies on a collision boundary of the Eurasian plate and the Indo-Australian plate.
Epicenter was 60-80km North west of Kathmandu. Focus was only 8km deep.
Nepal Earthquake case study ~ 2015
PRIMARY IMPACTS
Primary: 8841 deaths, over 19,000 injuries and 10 Billion USD of economic loss. 600,000 structures damadged and destroyed. UNESCO heritage sight collapsed.
Nepal Earthquake case study ~ 2015
RESPONSES
Short term: Survivors digging under rubble to find and help others, (national) search and rescue teams, support from overseas, medical teams providing emergency first aid.
Indian Airforce and Nepalese Army
Long Term: Charities from around the world helping the worst hit communities, took longer for supplies to reach remote villages. Providing shelter and food / emergency relief
