Tectonic hazards

Question 1

What is an earthquake?

Answer 1

A sudden and violent period of ground shaking, commonly caused by the sudden movement of rocks within the Earth’s crust.

Question 2

Where do earthquakes occur?

Answer 2

Mostly at plate margins. Lots around the edge of the Pacific Ocean. Some are human-induced and caused by fracking, mining and oil extraction.

Question 3

What is a tectonic plate?

Answer 3

A large section of the Earth’s crust.

Question 4

What is a tectonic plate margin?

Answer 4

The boundary between two tectonic plates.

Question 5

What is a volcano?

Answer 5

A large, often conical-shaped, landform created over a long period of time by a series of volcanic eruptions.

Question 6

Where are volcanoes found?

Answer 6

In long belts that correspond to plate margins. Around the edge of the Pacific Ocean (known as the Pacific Ring of Fire). Through the middle of the Atlantic Ocean.

Question 7

What are the 4 layers of the Earth called?

Answer 7

Crust, mantle, outer core inner core.

Question 8

What are the features of continental crust?

Answer 8

Cannot sink/be forced into the mantle. Less dense than oceanic. Older than oceanic – most is over 1500 years old. Cannot be remade or destroyed.

Question 9

What are the features of oceanic crust?

Answer 9

Can sink/be forced into the mantle. Denser than continental. Younger – most is <200 million years old. Can be remade or destroyed.

Question 10

Name a process that causes plates to move.

Answer 10

Slab pull / Ridge push.

Question 11

How do plates move at a constructive plate margin?

Answer 11

Apart from/away from one another.

Question 12

How are earthquakes/volcanoes created at constructive plate margins?

Answer 12

Plates move apart (e.g. North American Plate & Eurasian Plate). Magma forces its way to surface. Magma breaks through overlying crust = earthquakes. On surface, lava cools to form new crust. Repeated eruptions = layers of cooled crust = volcano. Sometimes volcano chains form.

Question 13

How do plates move at a destructive (C&O) plate margin?

Answer 13

Toward one another.

Question 14

How are earthquakes/volcanoes created at destructive (continental and oceanic) plate margins?

Answer 14

Plates move toward one another (e.g. Nazca Plate & South American Plate). Trench formed. Dense oceanic subducted under continental = friction = earthquakes. Oceanic melts in mantle, creating viscous magma = rises through surface, forming steep-sided volcanoes. Eruptions are violent and explosive.

Question 15

How do plates move at a destructive (C&C) plate margin?

Answer 15

Toward one another.

Question 16

How are earthquakes created at destructive (continental and continental) plate margins?

Answer 16

Plates Destructive (continental & continental). move toward one another (e.g. Indian Plate & Eurasian Plate). No subduction, no magma, no volcanoes. Plates collide = crust gets crumpled, uplifted & folded. Huge pressure builds, eventually released = severe earthquakes.

Question 17

How do plates move at a conservative plate margin?

Answer 17

Alongside one another.

Question 18

How are earthquakes created at conservative plate margins?

Answer 18

Plates move alongside one another (e.g. Pacific Plate & North American Plate). No subduction, no magma. Rough edges of plates grind past one another. Get stuck = huge pressure builds up = crumpled crust. Pressure released when plates slip, jerk or shift) = big earthquake, often close to surface, so devastating.

Question 19

At which plate margins is there no volcanic activity?

Answer 19

Destructive (continental & continental) and conservative.

Question 20

Which type of plate margin are the Himalayan Mountains sat on?

Answer 20

Conservative plate margin.

Question 21

When did the New Zealand earthquake occur?

Answer 21

14th November 2016

Question 22

How powerful was the New Zealand earthquake?

Answer 22

7.8 on the Richter Scale.

Question 23

Which plate margin caused the New Zealand earthquake?

Answer 23

The Pacific Plate is subducting beneath the Australian Plate - destructive plate margin.

Question 24

What were the primary effects of the New Zealand earthquake?

Answer 24

2 people died and over 50 people were injured. Tens of thousands of homes were damaged. 60 people were made homeless. The total cost of the damage was around $8.5 billion. Over 200km of road and over 190km of rail line were destroyed.

Question 25

What were the secondary effects of the New Zealand earthquake?

Answer 25

The earthquake triggered up to 100,000 landslides which blocked major road and rail routes. A major landslide blocked the Clarence River, resulting in flooding. The earthquake generated a tsunami with waves up to 5 metres in height.

Question 26

What were the immediate responses to the New Zealand earthquake?

Answer 26

Tsunami warning issued and people near the coast evacuated. Power was restored to most places within a few hours.

Question 27

What were the long term responses to the New Zealand earthquake?

Answer 27

$5.3 million of funding was provided by the Kaikōura District Council to help with rebuilding the town’s water systems and harbour. Most road and rail routes were repaired and reopened within 2 years. By March 2017, a permanent water main had been laid in Kaikōura. This new pipe was designed to move with any future earthquakes, so that it won’t break.

Question 28

When did the Nepal earthquake occur?

Answer 28

25th April 2015.

Question 29

How powerful was the Nepal earthquake?

Answer 29

7.8 on the Richter Scale.

Question 30

Which plate margin caused the Nepal earthquake?

Answer 30

The margin between the Indo-Australian Plate and Eurasian Plate (destructive C&C).

Question 31

What were the primary effects of the Nepal earthquake?

Answer 31

9,000 people died and over 22,000 people were injured. 800,000 buildings were damaged or destroyed. 4 million people were made homeless. The total cost of the damage was around $5 billion. Roads and bridges were destroyed, and 2 million people had no access to clean water and sanitation due to water tanks and pipes being destroyed.

Question 32

What were the secondary effects of the Nepal earthquake?

Answer 32

Avalanches on Everest killed 18 people. A lack of clean water caused typhus outbreaks, killing 13 people.

Question 33

What were the immediate responses to the Nepal earthquake?

Answer 33

India and China sent teams to help residents rescue people trapped by debris. Charities such as Oxfam provided medicine, food, and temporary water supplies. The Red Cross set up emergency shelters for 130,000 families who had lost their homes.

Question 34

What were the long term responses to the Nepal earthquake?

Answer 34

The World Bank Group financed $500 million worth of projects to build earthquake-resistant housing, and repair roads and irrigation systems. Some projects are still ongoing. NGOs are working with residents to increase their resilience to disasters by providing alternative energy sources.

Question 35

Why did Nepal suffer more than New Zealand did?

Answer 35

It is more densely populated and has high density housing. Building regulations are not strict/enforced well. Doesn’t have technology to monitor/predict disasters.

Question 36

Why did New Zealand suffer less than Nepal did?

Answer 36

Schools and workplaces hold regular earthquake drills. Emergency services work together, communicate and have specialised equipment.

Question 37

Why do people live in areas that are at risk from tectonic hazards?

Answer 37

May not be aware of the risks. May live in poverty & not have a choice about where to live. Volcanoes bring benefits e.g. fertile soils and valuable minerals = jobs. Better technology = people feel safer/protected.

Question 38

What are the 4 strategies for reducing tectonic hazards?

Answer 38

Monitoring, prediction, protection, planning.

Question 39

What is monitoring?

Answer 39

Using scientific equipment to detect warning signs of events such as volcanic eruptions.

Question 40

How can volcanoes and earthquakes be monitored?

Answer 40

V – remote sensing uses satellites to detect heat & changes to volcano’s shape. Instruments can detect gases released which might suggest rising magma. E – earthquakes generally occur without warning. Can monitor ground deformation but unreliable.

Question 41

What is prediction?

Answer 41

Using historical evidence and monitoring to make predictions about when/where a tectonic hazard might happen.

Question 42

Can volcanic eruptions and earthquakes be predicted?

Answer 42

V – prediction is based on scientific monitoring. Eyjafjallajokull eruption predicted based on increased earthquake activity beneath volcano. E – impossible to predict. Historical records can show which locations are at greatest risk.

Question 43

What is protection?

Answer 43

Designing buildings that will withstand tectonic hazards.

Question 44

How can we use protection to manage volcano and earthquake risk?

Answer 44

V – can use earth embankments & explosives to divert lava flows away from buildings. E – resistant buildings e.g. walls reinforced with concrete, shock absorbers to absorb ground shaking, auto window shutters to prevent broken glass falling.

Question 45

What is planning?

Answer 45

Identifying and avoiding places most at risk.

Question 46

How can we use planning to manage volcano and earthquake risk?

Answer 46

V – hazard maps show areas most likely to be affected = restrict certain land uses here & know where to evacuate first. E – hazard maps show areas most at risk from high damage. Hospitals & schools can be protected here.

Question 47

Which of the 4 forms of management are earthquake drills classed as?

Answer 47

Protection.