Hazards Flashcards
Define disaster.
A major hazard that causes widespread disruption to a community that may be unable to deal with the impacts without outside help.
Define hazard
A threat that has a potential to cause loss of life, livelihoods or socio-economic disruption.
Define hazard event
Occurrence of a hazard, the effects which cause demographic, economic, or environment changes.
Define hazard risk
The likelihood of a hazard causing harmful consequences.
Define risk
Probability and quantity caused by hazards that present threats to people.
Define fatalism
People choosing to accept the hazards will occur e.g. ‘God’s Plan’. There’s nothing one can do.
Define adaptive
People believe they can be prepared and survive hazards, very dependent on level of development.
Define the Hazard Management Cycle
Cyclical method of preparing for each disaster, focusing on before and after the hazard. Involved hazard identification, analysis of risks, prioritising greatest risks.
Implementing plans, public awareness and monitoring. After an event, infrastructure is repaired and the cycle repeats.
What are the three P’s for disaster management?
Predict - The Risk
Prevent - Mitigate
Protect - People and Property
What are some advantages of the hazard management cycle?
- Focuses on before the hazard.
- Easy to understand.
- Useful to assess pros and cons, what happened vs what should’ve happened.
- Can be applied to any hazard.
What are some disadvantages of the hazard management cycle?
- Certain sections of the cycle are vague.
- Favours HICs who have time, money, resources, and knowledge.
Define Park’s Curve
Shows how a country might respond to a hazard after it has occurred. Often used to understand resilience and preparation for future events.
How thick is the mantle?
2900km
What are the chemical layers within the mantle?
- Lithosphere.
- Asthenosphere.
- Mesosphere.D
Define lithosphere
Made of crust and solid upper mantle.
Define asthenosphere
Layer of upper mantle ductile, can move/reshape slowly.
Define mesosphere
More viscous because it is under pressure. Heat transferred unevenly, leading to plumes and hotspots.
How hot is the core of the Earth?
Around 5000 degrees c.
How does the core create the Earth’s magnetic field?
Core is mostly made of iron and nickel - these are magnetic. The outer core is also liquid which spins and creates the field.
What evidence is there to support the movement of tectonic plates?
- Jigsaw theory = Africa and South Africa ‘fit’ together.
- Similar fossils found on different continents.
- Coal found in Antarctica despite needing warm, wet conditions to form.
- Glacial deposits in Brazil that match Western Africa.
Who initially proposed Continental Drift and when?
Alfred Wegener in 1912.
Who discovered evidence for sea floor spreading in 1962 and what was it?
Harry Hess - Newer rocks were discovered in Iceland and older ones were located on shores of Caribbean and USA.
What method was used to confirm sea floor spreading?
Palaeomagnetism - The study of Earth’s magnetic field.
Define convection currents
Radioactive decay of isotopes create large temperatures. Hot air rises and forces plates away from each other before sinking. Not the driving force of plate movement!
Define ridge push
Lithosphere thickens with time and distance from mid ocean ridge. Boundary between lithosphere and asthenosphere becomes deeper and slopes away from ridge. Gravity acting on weight of lithosphere causes it to slide away.
Define slab pull
When an oceanic plate becomes so dense, it subducts under its weight and pulls rest of plate along with it.
Which plate boundaries do volcanoes occur at?
Converging - lots of volcanoes.
Diverging - less volcanoes but present.
- Transform - NO volcanoes.
Why are there lots of volcanoes in Hawaii?
Hotspot under Hawaii doesn’t move, but plate above does, so volcanoes become extinct when they move away and new islands form.
How does the silica content of lava determine explosivity?
Low silica content means low viscosity meaning less trapped gases. This leads to less explosive eruptions.
Name the three types of lava in order of silica content (lowest to highest)
Basaltic
Andesitic
Rhyolitic
What is another name for nuees ardentes?
Pyroclastic flows.
What are the different types of volcanoes?
- Acid dome
- Caldera
- Ash and cinder
- Shield
- Stratovolcano
How can volcanic eruptions be predicted?
- Seismicity weeks and days beforehand may be unusual.
- Tiltmeters measure the ground.
- Changing magnetism is an indicator.
- Rising magma heats groundwater.
- Measuring sulphur dioxide levels.