Models and Plate Tectonics Flashcards
How may people’s circumstances affect their perception of hazards?
Wealth - The risk is largely smaller for richer people as they have the means to adapt with and move away from disasters.
Religion - Some people may see natural hazards as an act of god.
Education - Better educated people may be able to understand the risk of hazards and may be more knowledgeable about how to overcome it.
Past experience - People who live in hazard prone areas may have experienced hazards before which can change their perception.
Personality - Some people may fear and others may get excited about disasters.
What does the Park Model look like?
It has 3 sections - RELIEF, REHABILITATION and RECONSTRUCTION which take place over varying time scales which a line representing the normality of the area throughout, the line also passes into three categories rating the quality of life - BETTER, NORMAL and WORSE with the opportunity to improve or to return to normal in the reconstruction stage.
What are the four phases of the Hazard Management Cycle?
MITIGATION - Minimising the impact of future disasters e.g Earthquake-proof buildings.
PREPAREDNESS - Planning how to respond e.g evacuation drills.
RESPONSE - How people react during the disaster e.g Rescuing trapped people.
RECOVERY - Getting the area back to normal e.g repairing buildings.
What are the characteristics of the inner and outer core?
The inner core is a solid ball of Iron and Nickel.
The outer core is semi-molten and also contains iron and nickel.
What is the rigid top part of the mantle (ASTHENOSPHERE) and crust collectively know as?
The LITHOSPHERE
What are the characteristics of Continental and Oceanic plates?
Continental crust is thicker at around 30-70km and less dense.
Oceanic crust is thinner (6-10km) and more dense.
How do convection currents move tectonic plates?
As the earths mantle is hottest closer to the core the surrounding rocks heat up, become less dense and rise, as they move towards the top of the asthenosphere they cool down, become more dense and begin to sink, these circular movements create drag, moving the plates.
What is slab pull?
At destructive plate margins denser crust is forced under less dense crust, the sinking of the plate pulls the rest of the plate towards the boundary.
What is ridge push?
At constructive plate boundaries magma rises to the surface creating new crust, the crust is very hot which expands the surrounding rocks resulting in a slope. Gravity then pulls the rocks downwards, shifting the plate. Also known as gravitational sliding.
What is sea-floor spreading?
As convection currents cause tectonic plates to diverge, magma rises up to fill the gap created pushing the plates apart causing the sea-floor to spread, this also creates mid ocean ridges.
What are constructive margins and what do they create?
A constructive margin is when two plates are DIVERGING (moving apart).
As the plates rarely move at uniform rates this leads to pressure which can create cracks and fault lines causing damaging earthquakes.
When the pressure is released it can also result in volcanoes.
Constructive margins create OCEAN RIDGES between two oceanic plates and RIFT VALLEYS between two continental plates.
What is an Ocean Ridge?
An ocean ridge is when two plates diverge underwater and pressure is released creating underwater volcanoes that create mid ocean ridges such as the Mid-Atlantic Ridge, that can sometimes build up to be above sea level e.g Iceland.
What is a Rift Valley?
A Rift Valley is when plates diverge under land, as the plates diverge the land drops down between them. E.g The East African Rift System.
What are Destructive margins and what do they create?
A destructive margin occurs where two plates are converging (moving towards each other).
At Oceanic-Continental boundaries the denser Oceanic plate is subducted under the lighter Continental plate, this forms a DEEP SEA TRENCH, the pressure of the oceanic plate melting (caused by friction) uplifts the continental plate creating FOLD MOUNTAINS. Either plate can become stuck and cause earthquakes in the BENIOFF ZONE and the magma is lighter so rises above the continental plate creating volcanoes.
At Oceanic-Oceanic boundaries the denser of the plates is subducted and the rising magma creates ISLAND ARCS e.g the Mariana Islands.
Continental-Continental, Neither plate is subducted so there aren’t any volcanoes but the pressure leads to the creation of FOLD MOUNTAINS e.g the Himalayas
What are conservative plate margins and what do they create?
This is when two plates are moving past each other and become locked together in places causing pressure to build up, as they jerk past each other their energy is released as an earthquake. E.g San Andreas Fault, California.
