Unit 1 - Restless Earth Flashcards
Describe the differences between oceanic and continental crusts
OCEANIC -
•Under the ocean
•Thin but dense
•Made from basalt
CONTINENTAL -
•Under land
•Thick but less dense
•Made of granite
Describe the layers of the earth
Crust - 0-50km thick
Mantle - 3000km thick, semi solid consistency (custardy)
Outer Core - 2300km thick, iron/nickel liquid consistency
Inner Core - 1200km thick, iron/nickel, solid consistency
Describe how convection currents move tectonic plates
The mantle is warmed by the core
The mantle rises to the earth’s surface
The movement of the magma in the mantle pulls the tectonic plates
The molten rock cools and sinks back towards the core
What is the lithosphere?
The crust and upper mantle
What is the asthenosphere?
The upper mantle just below the lithosphere
How do we know the plates move?
The plates used to be joined as one giant plate know as Pangea.
Fossils of the same species were found on the east of South America and west Africa suggesting they were once all joined
Describe a constructive plate boundary
Where 2 oceanic plates are moving away from each other.
Magma is drawn up in the gap forming new crust when it cools
Give an example of a constructive plate boundary
Mid-Atlantic Ridge
Describe a destructive plate boundary
Where an oceanic plate meets a continental plate and the denser oceanic plate is subducted underneath the less dense continental plate
Give an example of a destructive plate boundary
The Andes Mountains, Peru, Chile
Describe a conservative plate boundary
Where 2 plates slide past eachother
Give an example of a conservative plate boundary
San Andreas Fault, California, USA
Describe a collision plate boundary
Where 2 continental plates collide pushing upwards to form mountains
Give an example of a collision boundary
The Himalayas, Asia
Describe the Hot-spot Theory
The Hot-spot Theory is the idea that magma plumes rise in the mantle causing islands such a Hawaii miles away from plate boundaries
What is the scaled called used to measure volcanic eruptions?
VEI - Volcanic Explosivity Index
From 1 - 8
What is the most common scale used to measure the magnitude of earthquakes?
The Richter Scale
1-10 but each level is 10x stronger than the previous level
How are volcanic eruptions predicted?
Tiltmeters - detect when volcanoes swell up
Seismometers - monitor earth tremors (which increase as magma rises)
Aircraft - record the levels of gas given off by a volcano
How are earthquakes predicted?
Seismometers - sense vibrations in the earth’s crust
Radon Gas - a gas that escapes from cracks in the earth (more gas means greater risk of earthquake)
At what plate boundaries are earthquakes most common?
Destructive boundaries
Conservative boundaries
Collision boundaries
At what boundaries are volcanoes formed?
Constructive boundaries
Destructive boundaries
State an earthquake that occurred in an LEDC
Haiti 2010 7 on the Richter scale 220,000 deaths 300,000+ injured Hospitals and schools destroyed Airport and port damaged
