Topic 1 EQ1 Flashcards
What is the tectonic location of Nepal?
Sits on a fault between the Indian and Eurasian tectonic plates. Plate compression leads to pressure build up
What is a natural hazard
A naturally occurring event caused by natural processes
What is a natural disaster?
When a natural hazard causes social and environmental damage
What is vulnerability ?
People’s ability to cope with hazard events
What does the Degg model show?
The overlap between hazardous events and vulnerable population which causes a disaster
What magnitude was the 2015 Nepalese earthquake?
7.8
How many deaths were caused by the 2015 Nepal earthquake?
8633
Cost of the 2015 Nepalese earthquake
Lost 25% of GDP
Cost 6.6 billion to rebuild which they would have to rely on foreign aid
Human Vulnerabilities of Nepal
- half the population lives in poverty
- buildings weren’t built to withstand earthquakes
- lack of investment in emergency services meant that they had to rely heavily on foreign aid
- economy is very reliant on tourism
Physical vulnerability of Nepal
Mountainous landscape meant that shaking caused landslides
Earths structure
Core : inner and outer
Mantle - upper and asthenosphere
Crust - oceanic and continental
Characteristics of inner core
Solid
Made of iron
About 6000°c
Characteristics of the outer core
Semi molten
Liquid iron and nickel
4500 - 6000°c
Mantle characteristics
Widest
Upper mantle is solid
Lower mantle is the asthenosphere which is semi molten rock
Oceanic crust characteristics
Thin dense layer (6 - 8 km thick)
Characteristics of continental crust
Thicker less dense layer
45 - 50 km
What is the lithosphere made up of ?
Crust and upper mantle which is made up of tectonic plates
How does mantle convection cause plates to move?
Heat produced by radioactive decay in the core heats the lower mantle which creates convection currents in the asthenosphere and cause the plate to move
What is seafloor spreading
Occurs at divergent boundaries under the ocean and there is a continuous input of magma which forms a mid ocean ridge.
Paleo magnetism can be used to date the age of the new tectonic crust
What is paleomagnetism?
A record in the changes of the Earths magnetic field
How does paleomagnetism show that the sea floor has spread?
When lava solidifies , minerals line up with the earths magnetic direction. Mid ocean ridges show patterns of magnetic direction mirrored on each side of the ridge
Why did subduction become suggested?
If sea floor spreading creates new crust, then the Earth should be expanding which means that crust must be getting destroyed somewhere.
What is subduction?
A two plates move towards each other , the denser plate slides under into the mantle where it melts
