The Restless Earth

Question 0

What is the contrast between oceanic and continental crust?

Answer 0

Oceanic is denser, thinner, can sink and is subducted under the continental.

Question 1

Describe the distribution of plates.

Answer 1

Some countries are only on 1 plate but some can lie between 2.

Question 2

What are the 4 plate margins?

Answer 2

Destructive, constructive, collision and conservative.

Question 3

What happens at a destructive plate boundary?

Answer 3

Oceanic plate subducts under continental plate forming fold mountains, ocean trenches and volcanoes.

Question 4

What happens at a constructive plate boundary?

Answer 4

The 2 plates move apart. The convection (rising) in mantle cools and spreads out as it nears the surface, making magma fill the gap forming volcanoes.

Question 5

What happens at a collision plate boundary?

Answer 5

2 continental plates move towards each other, pushing the crust upwards forming fold mountains.

Question 6

What happens at a conservative plate boundary?

Answer 6

Plates slide past each other causing friction to build up and create stress. When the stress is released it lets off energy forming earthquakes.

Question 7

Where and how do fold mountains occur?

Answer 7

Occur at collision and destructive boundaries.

Sediment deposited on the ocean floor gets pushed upwards overtime.

Question 8

Where and how do ocean trenches occur?

Answer 8

Occur in deep sections of the ocean on destructive plate boundaries.
An oceanic plate gets subducted underneath a continental plate.

Question 9

How are composite and shield volcanoes formed?

Answer 9

Composite volcanoes formed on destructive boundaries by layers of hardened lava, tephra, pumice and ash building up a steep slope.
Shield volcanoes formed on constructive boundaries by thin layers of lava building up a gentle slope.

Question 10

Outline the Andes fold mountain case study.

Answer 10

Happened in South America west coast.
7000 km long, 300 km wide, 4000 m tall.
Used for farming (terraces, crops, llamas), mining (exporting, gold mines, minerals), hydroelectricity (rapid flow, easily dammed) and tourism

Question 11

What are the characteristics of volcanoes?

Answer 11

Found at constructive and destructive boundaries. Can be underwater. Magma when inside volcano; lava when erupted. Composite and Shield.

Question 12

Outline the Soufriere Hills volcano case study.

Answer 12

Happened in Montserrat, Caribbean when the North American plate subducted under the Caribbean plate (magma>pressure>forced though cracks).
Evacuation, aid sent, charities, job loss, 19 dead.
No more tourism and loss of vegetation, South still unsafe.

Question 13

How are eruptions monitored and predicted?

Answer 13

GPS Satellite detects movement. Seismometers detect the tiny earthquakes that usually occur before an eruption. Certain sounds. Gas seeps out when it is close to erupting.

Question 14

What is a supervolcano?

Answer 14

A mega colossal volcano that erupts and causes wide-scale damage.

Question 15

What are the characteristics and likely effects of a supervolcano?

Answer 15

1000-3000 km3 of ash in air. Ash fall 1-5 m deep. Dust cloud could cause volcanic winter for 5 years>ice age. Destroys everything in its path within 500 km. Can trigger tsunamis. Poisonous gases pollute water and rain.

Question 16

Where and how do earthquakes occur?

Answer 16

Occur at conservative boundaries.

The friction between 2 plates releases energy to cause the earthquake.

Question 17

Describe the features of an earthquake.

Answer 17

Vibration of the earths crust due to release of energy.
The focus is the point where the earthquake happens. The epicentre is where the earthquake reaches the surface directly above.

Question 18

How are earthquakes measured?

Answer 18

Seismometers record earthquake at the time they’re happening.

Richter scales (measure earthquakes based on seismometer readings) and Mercalli scale (descriptions of damage from I to XII)

Question 19

Outline the MEDC Northridge earthquake case study.

Answer 19

Happened in LA suburb on Pacific and North American conservative plates (they go the same direction>cracks>pressure>rock slid upwards).
6.7 on Richter scale. Damage was $15bil.
Most people were asleep under quake proof buildings, broken gas mains shot fireballs, electricity repaired in hours, food served, emergency services ready, compensation, help kits, 57 dead.

Question 20

Outline the LEDC Haiti earthquake case study.

Answer 20

Happened in Port Au Prince on North American and Caribbean conservative plate.
7 on Richter scale. 6 aftershocks.
Houses gone, destroyed infrastructure, thousands injured, no communication, cholera, corpses everywhere, confusion, food/water needed, mass graves, 230,000 dead.

Question 21

Describe the responses to earthquakes.

Answer 21

Developing the 3p’s, worldwide aid, emergency services, building quake proof buildings, charities, bringing supplies, rescuing, evacuating quickly.

Question 22

Outline the Japan tsunami case study.

Answer 22

Happened mainly at Fukishima after earthquake struck (plate stresses and buckles>pressure>jolt>water displacement).
9.2 magnitude. Around 35 m waves.
Hard to escape, degree swept away, powerplant meltdown leaking radiation, no transport, coast sunk, infertile land, fires from oil on water and electricity, warning system to alert people, coastal defences were too weak and short, 18000+ dead.