The Restless Earth

Question 1

What are the differences between Oceanic and Continental crust?

Answer 1

Oceanic is Denser, 6km thick, newer (less that 200m yrs old)

Continental is less dense, 35-70km thick, older (more than 3500m yrs old)

Question 2

Why do tectonic plates move?

Answer 2

because of convection currents in the mantle under the earths crust; heated rock in mantle rises, semi-molten rock spreads out carrying the above plate with it

Question 3

What is a destructive plate boundary?

Features?

Answer 3

where 2 plates (oceanic and continental) are moving towards each other
Ocean trenches, volcanoes, earthquake activity

Question 4

What is a constructive plate boundary?

Features?

Answer 4

where 2 plates (oceanic) are moving away from each other

Volcanoes

Question 5

What is a collision plate boundary?

Features?

Answer 5

where 2 continental crusts move together

Fold mountains

Question 6

What is a conservative (slip) boundary?

Features?

Answer 6

where 2 plates (continental) are moving past each other or in the same direction but at different speeds
earthquake activity

Question 7

What are ocean trenches?

How are they formed?

Answer 7

deep canyons on the sea floor
found at destructive margins; oceanic and continental crust moves together, oceanic is denser so it is forced to sink down at the zone of subduction taking the sea floor with it - leaving the ocean trench.

Question 8

How are fold mountains formed?

Answer 8

they are found at collision and destructive plate margins

they occur when plates move together and the land between is folded and buckled upwards

Question 9

What problems do people face living in fold mountain areas?

Answer 9

land is steep; bare rocky outcrops makes building hard
flat valley floor; subjected to flooding, crops are destroyed
hard to build roads/ railways; require many roads with hairpin bends
mountainous soils are often thin and infertile; poor crops

Question 10

What is a volcano and why do they occur?

Answer 10

caused by the movement of destructive and constructive tectonic plates
Destructive: oceanic plate moves down and is destroyed, a pool of magma forms, the magma rises through cracks called vents, magma erupts of the surface - volcano
Constructive: magma rises up into the gap caused when the plates move apart - volcano

Question 11

Features of a shield volcano?

Answer 11

made up of just layers of lava
lava is runny, flows quickly and spreads over a wide area
forming a low, flat volcano
eg. Mauna Loa, Hawaii

Question 12

Features of a dome volcano?

Answer 12

made up of just layers of lava
lava is thick, flows slowly and hardens quickly
forming the steep sided dome shaped volcano
eg. Mount Pelle, Caribbean

Question 13

Features of a composite volcano?

Answer 13

made up of ash and lava
cooled and hardened into layers
lava is thick, flows slowly and hardens quickly
forming the steep sided volcano
eg. Mount Fuji, Japan

Question 14

How and why are volcanos monitored and predicted?

Answer 14

scientists try to predict earthquake activity; things such as tiny earthquakes, escaping gas and changes in volcanoes shape are all signs

Question 15

How is a super volcano different from a normal volcano?

Features?

Answer 15

they are much bigger than a standard volcano
flat
cover a large area
have a caldera (big crater)

Question 16

What are earthquakes and why do they occur?

Answer 16

plates can get stuck as they move, tension builds up and when this tension is eventually released the plates jerk past each other, sending out shock waves (vibrations)
the vibrations are the earthquake

Question 17

Whats the difference between the focus and epicentre of an earthquake?

Answer 17

the Focus is where the seismic waves start

the Epicentre is directly above, on the surface

Question 18

How is the Richter scale used to measure earthquakes?

Answer 18

Measured using scientific equipment (seismometer)
one level is 10x stronger than the previous
it has 10 levels (0-1.9, 2-2.9…)
higher the level, stronger the magnitude

Question 19

How is the Mercalli scale used to measure earthquakes?

Answer 19

based on eyewitness observations (damage done)
has 12 levels (1,2,3…)
higher the level, stronger the magnitude

Question 20

What is a tsunami?

Answer 20

a series of enormous waves caused when huge amounts of water get displaced

Question 21

5 ways in which people use fold mountain areas?

Answer 21

Farming, Tourism, Mining, Forestry, HEP