What are that x4 processes that drive tectonic plate movement?
- Mantle Convection
- Sea Floor Spreading
- Slab Pull
- Subduction
What is a natural hazard?
A naturally occurring process or event that has the potential to affect people
What is a natural disaster?
A major natural hazard that can cause significant social, economic and environmental damage to a vulnerable population
What is vulnerability?
The ability to anticipate, cope with, resist and recover froma natural hazard
Why is Nepal vulnerable to natural hazards?
- Monsoon rain
- Poor infrastructure
- Excessive snow melt
- Poor technology
- Poor economy
- Located on a plate boundary
- Relief rainfall
What is the inner core?
- Hottest part of the Earth - heat is generated by radioactive decay
- Solid due to extreme temperatures & pressure
- Consists of ion
What is the outer core?
- Temperatures range from 4500 to 6000
- Semi molten
- Consists of liquid iron and nickel
What is the mantle?
- Cooler
- Semi molten
- Consists mostly of silicates
- Thickest layer
- Upper mantle can be split into two layers - lithosphere and asthenosphere
What is the crust?
- Temperatures range form 200 to 400
- Solid
- Thinnest layer of the Earth’s structure
- 2 types of crust - oceanic (thin and dense) and continental (thicker, older & less dense)
What is the lithosphere?
Thin solid layer where tectonic plates are formed
What is the asthenosphere?
Semi molten layer which tectonic plates ‘float’ upon
What is mantle convection?
- Long thought to be responsible for plate movement
- Heat produced by the decay of radioactive elements in the core eats the lower mantle - creating convection currents
-These cause the plates to move
What is slab pull?
- Increasingly seen as a major driving force for plate movement
- Newly formed oceanic crust at mid-ocean ridges becomes denser and thicker a it cools
- This causes it to sink into the mantle under its own weight pulling the rest of the plate further down with it
What is subduction?
- As new crust is being created in one place, its being destroyed in another - by subduction
- As two oceanic plate move towards each other, one slide under the other into the mantle - where it melts in an and are known as a subduction zone
What is seafloor spreading?
- In the middle of many oceans are huge made-ocean ridges, or underwater mountain ranges
- These are formed when hot magma is forced up from the asthenosphere and hardens - forming new oceanic crust
- The new crust pushes the tectonic plates part in a process called seafloor spreading
What is paleomagnetism?
The study of past changes in the Earth’s magnetic field
What is a plate boundary?
Place on Earth’s crust where two or more plates meet
What is a plate margin?
The area either side of the plate
What is a Benioff Zone?
Area where plates make contact and friction occurs - results in an earthquake
What is an Island Arc?
A long chain of active volcanoes with intense seismic activity found along convergent plate boundaries?
What is a Mid-Ocean Ridge?
Seafloor mountain system formed at divergent plate boundaries
What is a Rift Valley?
Steep-sided valley formed at divergent plate boundaries when the land between faults collapses
What happens at convergent plate boundaries?
- Plates move toward each other
-3 types
-Oceanic meets continental
-Oceanic meets oceanic
-Continental meets continental
What happens at divergent plate boundaries?
- 2 plates move apart
-Leads to formation of new crust - Forms mid-ocean ridges and rift valleys
