Restless Earth

Question 1

Name 2 features of continental crust

Answer 1

30-50km thick and made of granite (low density igneous rock)

Question 2

Name 2 features of oceanic crust

Answer 2

6-8km thick and made of basalt (higher density igneous rock)

Question 3

How are earthquakes caused at conservative boundaries?

Answer 3

As plates slide past each other, friction between them causes earthquakes. These are rare but very destructive

Question 4

How are volcanoes formed at constructive boundaries?

Answer 4

As plates move apart, magma rises up through the gap. The magma is basalt and is very hot and runny. It forms lava flows and shallow sided volcanoes

Question 5

How are earthquakes caused at constructive boundaries?

Answer 5

Earthquakes are caused by friction as the plates tear apart. These earthquakes are small and don’t do much damage

Question 6

How are volcanoes formed at destructive boundaries?

Answer 6

As plates push together the oceanic plate is subducted. As it sinks it melts and makes magma called andesite. Sea water is dragged down with oceanic plate making the magma less dense so it rises through the continental crust. The water erupts as very explosive steam

Question 7

How are earthquakes caused at destructive boundaries?

Answer 7

Sinking oceanic plate can stick to the continental plate. Pressure builds up against the friction. When the plates finally snap apart a lot of energy is released as an earthquake. They can be devastating, especially if shallow

Question 8

Give an example of a conservative plate boundary

Answer 8

The San Andreas Fault

Question 9

What is the Volcanic Explosivity Index?

Answer 9

The VEI measures destructive power of a volcanic eruption on a scale of 1 to 8

Question 10

Give two advantages of the volcano Sakurajima in Japan

Answer 10

40% of the land is fertile volcanic soil, growing tea and rice. Hot springs and lava flows are a popular tourist attraction; the area is a national park

Question 11

How many people live at the base of the volcano Sakurajima in Japan?

Answer 11

7000 people

Question 12

Give a disadvantage of the volcano Sakurajima in Japan

Answer 12

The nearest city, Kagoshima, has a population of 650,000; a big eruption could devastate it with ash, lava bombs and pyroclastic flows

Question 13

How are aircraft used to predict a volcanic eruption?

Answer 13

They measure the amount of gas given off by the volcano, which would increase as the chance of an eruption increases

Question 14

How are tiltmeters used to predict a volcanic eruption?

Answer 14

They detect when a volcano swells up and fills with magma

Question 15

How are seismeters used to predict a volcanic eruption?

Answer 15

They monitor earthquakes, which would increase as the chance of a volcanic eruption increases

Question 16

How do concrete lahar channels protect against volcanic eruptions?

Answer 16

They divert dangerous mud flows

Question 17

How do concrete shelters protect against volcanic eruptions?

Answer 17

They protect against volcanic bombs and ash

Question 18

Why are tectonic hazards increased in developing countries?

Answer 18

People live in risky locations as there’s nowhere else to live
Can’t afford safe well-built homes so often buildings collapse
They don’t have insurance
Governments don’t have money and resources to provide aid
Poor communications so warning and evacuation may not happen

Question 19

Where and when did Mount Nyiragongo erupt?

Answer 19

Democratic Republic of Congo in January 2002 on a constructive plate boundary - hot and runny basalt lava

Question 20

What were the primary effects of the eruption of Mount Nyiragongo?

Answer 20

River of lava 1000m wide, 20km long flowed into city of Goma
14 villages destroyed + 12,500 homes
100 people died from lava + poisonous gas
400,000 people evacuated, many became refugees
Earthquakes triggered

Question 21

What were the secondary effects of the eruption of Mount Nyiragongo?

Answer 21

120,000 people homeless
Little clean food + water so cholera spread
In first week UN sent 260 tonnes of food
Governments around world gave $35 million to aid refugees
By June 2002 some roads cleared and water supply repaired

Question 22

What are the focus and epicentre of an earthquake?

Answer 22

An earthquake starts at the focus. The epicentre is the point on the Earth’s surface above the focus and is the first place to shake

Question 23

What happened in the Nigata (Japan) earthquake in 2007?

Answer 23

In city of 90,000, 11 people died + 1000 injured
350 buildings destroyed
Tsunami warning issued but false alarm
Epicentre offshore so less shaking on land
Happened at 6pm - people alert and remembered drill

Question 24

What happened in the Kobe (Japan) earthquake in 1995?

Answer 24

City of 1.5 million - very high population density
5000 died and 26,000 injured
Many fires started and couldn’t be reached due to collapsed buildings
Damage was $200 billion
Epicentre was close to Kobe
Happened at 6am - people were asleep and confused in the dark

Question 25

Name 3 features of earthquake contingency planning in Japan?

Answer 25

Every year Japan has earthquake drills
Emergency services practise rescuing people
People keep emergency kits at home containing water, food, a torch and radio

Question 26

Name 6 features of an earthquake proof building in a developed country

Answer 26

Damper in roof acts like pendulum reducing building sway
Shock absorbers built into cross braces
Strong double glazed windows stop broken glass showering down
Very deep foundations to prevent collapse
A strong steel flexible frame prevents cracking
Cross bracing stops floors collapsing

Question 27

When and where did the Sichuan earthquake occur?

Answer 27

In a province in central China on 12 May 2008

Question 28

What were the primary impacts of the Sichuan earthquake?

Answer 28

Magnitude 8.0 earthquake
70,000 people died
400,000 people injured
5 million people made homeless
up to $75 billion in damage

Question 29

What were the local responses to the Sichuan earthquake?

Answer 29

Heavy rain, landslides and aftershocks made rescue effort very difficult
50,000 soldiers sent to help dig for survivors
Helicopters issued to help reach isolated areas
Chinese people donated $1.5 billion in aid

Question 30

What were the international responses to the Sichuan earthquake?

Answer 30

UK gave $2 million
Finland sent 8000 tents
Indonesia sent 8 tonnes of medicine
Rescue teams flew in from Russia, Hong Kong, South Korea and Singapore

Question 31

Name 5 features of an earthquake proof building in a developing country

Answer 31

Cross braced wood or bamboo frame
Concrete ring ties the walls to the foundations
Lightweight thatch roof
Walls made of mud and straw packed between wooden slats
Simple steel rod foundations