Tectonic Hazards

Front 1

Describe and comment on the global distribution of earthquakes, volcanic eruptions and tsunamis

Back 1

All three tectonic hazards occur on or near plate boundaries. All tectonic hazards occur on convergent plate boundaries. Earthquakes only on transform and volcanoes and earthquakes on constructive

Front 2

Describe and explain the distribution of plate boundaries and compare divergent convergent and conservative plate movements.

Back 2

Convergent - One plate is bring subducted under the other

Divergent - two plates are moving apart

Transform - two plates are moving past each other

Front 3

Determine the cause of intra-plate earthquakes

Back 3

Nuclear weapons - atomic bombs release lots of energy that can send seismic waves through the earths crust.

Fracking - by recovering natural gas and injecting water to replace it. This injection creates cracks and if a crack is created near a fault it can release the strain built up along the fault.

Intra-plate faults - New Madrid fault was formed from a break up of the supercontinent Rodinia. The break up failed leaving a permanent scar on the earths crust, a intra-plate fault.q

Front 4

Determine the causes of intra-plate volcanoes

Back 4

Mantle plumes - When superhot liquid rock in the mantle is hot enough it can punch through the earths crust creating a hot spot that can be located in the middle of a plate e.g. Hawaii.

Front 5

What are the four types of volcanoes and give an example?

Back 5

Shield e.g Mauna Loa, Hawaii

Cinder done e.g Mount Zion, Israel

Composite cone e.g. Mount St Helens

Front 6

What is the inner core made of?

Back 6

Solid iron nickel ball

Front 7

What is the outer core made of?

Back 7

Liquid semi-molten rock

Front 8

What is the mantle?

Back 8

Upper part is the Asthenosphere has plastic properties allowing convection currents to occur.

Front 9

What is the lithosphere?

Back 9

The crust and the immediate upper rigid part of the mantle

Front 10

What is the crust?

Back 10

Floats on top of the asthenosphere. Two types of crust continental crust and Oceanic crust

Front 11

What is the difference between continental crust and oceanic crust?

Back 11

Continental crust - less dense, older and lighter

Oceanic crust - more dense, younger and heavier

Front 12

What happens at a divergent plate margin?

Back 12

- 2 plates are moving apart

- can form shield volcano when rising magma cools and solidifies or islands such as Surtsey in Iceland.

- When 2 oceanic move apart = ocean ridges

- When two continental move apart = rift valley

Front 13

What happens at a destructive plate boundary?

Back 13

- subduction occurs where an oceanic plate is forced under a continental plate - volcanoes and deep sea ocean trenches are formed

-2 oceanic plate meet = island arc

- 2 continental meet = fold mountains

Front 14

How are fold mountains formed?

Back 14

Fold mountain is formed where two plates meet at a geosyncline as these plates come together the geosyncline the sediments get compressed. As the sediment become even more compress the geosyncline begins to disappear and a new mountain ranges formed like the Himalayas. They are equally formed at subduction zones as well like the Andes in South America

Front 15

How is an island arc formed?

Back 15

When two oceanic plates come together one plate can subduct under the other. This oceanic plate will be melted and become molten magma. This molten magma will reach the surface creating a volcano as time passes. Except as the plate moves the magma chaebol will move in the process causing the volcano to be extinct as it willno longer have a chamber to fuel it this will create an island arc like the Caribbean and Hawaii.

Front 16

What happens at a conservative plate margin?

Back 16

Two plates sliding against each other e.g San Andreas.

Front 17

What are convection currents?

Back 17

Convection currents are what drive plate movement.

1) Heat produced by radioactive decay in the earths core heats the lower mantle.

1) Hot molten rock rises in the mantle heated by the earths core

2) Below the crust, the molten rock spreads sideways, beginning to lose heat

3) Eventually the cooler rock sinks back down filling the gap left by the rising rock.

4) Through this process the crust is dragged very slowly (3 to 5 cm a year)

5) This process of moving the crust over very long period of time from a supercontinent called Pangaea to the current day is known as Continental drift

Front 18

What was Alfred Wagner's theory on continental drift?

Back 18

Where can I believe that all continents were once all joined together Pangaea opposing the idea at the time that they were connected via land bridge is long since sunk. It was not generally accepted at the time by scientist he didn't have enough evidence but he did notice that there was similar fossils of animals located in Africa and South America

Front 19

What was Harry Hess theory on continental drift?

Back 19

Dr Hess believed that hot magma would rise from under the crust at the global rift. When it cooled it would expand and push tectonic plates apart. We know this today as convention currents in the mantle. He discovered Sea floor spreading. Wegener theory started to become more accepted.

Front 20

What was Morley, Vine and Matthews theory on continental drift?

Back 20

They believed that magnetic anomalies under the earths surface. When lava cools and becomes rock manual inside the rock lineup with the earth's magnetic direction at the time. Every 400,000 years the earths poles change direction. They metallic elements within the magma are attracted to the earths magnetic field. Over time both sides of the mid Atlantic ridge demonstrated exact changes in polarity at the same time.

Front 21

What is palaeomagnetism?

Back 21

The study of past changes in the earth's magnetic field (determined from rocks and sediments or archaeological records)

Front 22

What further evidence is their for continental drift?

Back 22

Biological - fossil formations found on either side of the Atlantic) for example mesosaurus freshwater reptile) found both in south-west Africa and in Brazil

Climatological - coal and oil deposits found in Antarctica suggest that it was once in a different climatic zone for these to have form

Geological - same type age and formations of rock found on two sides of the Atlantic Appalachian mountains in North America and Caledonian Mountains in Scotland both have igneous and sedimentary rock sequence

Front 23

What is basaltic lava and what are the characteristics

Back 23

Laugher it formed commonly a constructive plate boundaries low silica content, low viscosity and very hot

Front 24

What is Andesitic lava and what are the characteristics?

Back 24

Formed commonly at destructive plate margins medium silica content and viscosity and temperatures roughly 800°C

Front 25

What is Rhyolitic lava and what are the characteristics?

Back 25

Formed commonly at destructive plate margins high silica content and viscosity low temperature. E.g Yellowstone

Front 26

What are the characteristics of a Shield volcano?

Back 26

Liquid Lafaette emitted from a large central vent or group of vents, gently sloping, flat shape and low lying. Eruptions are gentle, frequent and predictAble.

Front 27

What are the properties of a Cinder cone volcano?

Back 27

Explosive liquid lava, small in size, central vent, pyroclastic material composed of ash and cinders

Front 28

What are the properties of a composite cone volcano?

Back 28

Explosive and unpredictable eruptions, steep sided, viscous lava, explosive pyroclastic eruptions

Front 29

Montserrat, Caribbean - 1995 (LEDC)

Back 29

Info:

Part of Island arc formed from from two oceanic plate meeting, Caribbean and North American

Until 1995, economy based on farming, fishing and tourism

Primary effects:

Pyroclastic flows & floods as valleys were blocked by ash

Vegetation and farmland destroyed

20 villages and 2/3 of homes were destroyed by pyroclastic flows

Tourism came to a halt

Health problems from harmful gases and ash

Secondary effects:

Forest fires caused by pyroclastic flows

23 people died as a result of pyroclastic flows burning them alive

More than half of Montserrat uninhabitable

Ageing population as many young people left the island (4,000 people went to the UK)

7000 (2/3 of people) have left the island

Destroyed capital city

Short term responses:

Abandons capital city of Plymouth

By November 1997 population fell from 12,000 to 3,500

Long term responses:

Volcanic observatory built in 1996 to monitor the volcano

British government gave £200 million for compensation and redevelopment.

Presence of volcano = growth in tourism

Front 30

Eyjafjalljökull, Iceland - 2010 (MEDC)

Back 30

Info:

On Mid-Atlantic ridge

Shield volcano surrounded by ice and water (ice cap)

Underwater ice cap mean a eruption similar to composite volcano as hydrogen in water mixes with lava making it thicker and acidic.

Main effects:

Less demand for air fuel = loss of money for oil industry

Stock market sharing air travel and tourism agencies dropped 40%

Airspace closed across much of Europe more than 7000 flights a day cancelled

Increased use of Eurostar train services ships and ferries

Flash flood damage to fields and homes in Iceland but increased tourism

Increased spending by people who are stranded in the UK for hotels and food Tec

Responses:

Launched a massive Europe wide review of safety of planes going through ash clouds

Front 31

What is an earthquake?

Back 31

An earthquake is a motion of the ground surface, ranging from a faint tremor to a wild motion capable of shaking buildings apart.

Front 32

How is an earthquake caused?

Back 32

Produced by sudden slip movements along faults, volcanic activity or man made influences (digging, building, mining etc) such as cracking which has been known to cause tremors.

Front 33

Where are earthquakes common?

Back 33

Along ocean trenches (at subduction zones)

In regions where continental plates are colliding (Nepal)

Along ocean ridges (Iceland)

Transform faults (San Andreas fault)

Front 34

What is the focus?

Back 34

The point where the fault ruptures first

Front 35

What is the epicentre?

Back 35

Above the focus on the surface, where seismic energy is strongest

Front 36

What are seismic waves and how are they caused?

Back 36

They are waves of energy that are caused by sudden breaking of rock within the Earth or an explosion.

Front 37

What are the effects of earthquakes

Back 37

Primary:

Ground Shaking

Secondary:

Soil liquefaction (seen in Japan 2011) soil loses mechanical structure and behaves like a liquid

Landslides (slope failure due to ground shaking)

Collapse of infrastructure - buildings, transport systems, power lines etc

Destruction of utilities - water, gas, electricity along with internet connections

Fires - ruptured gas mains, fallen power lines

Flooding - from groundwater & mains water

Disease and food shortages

Knock on effect -> start a tsunami e.g. Japan 2011

Front 38

What are the main types of seismic waves?

Back 38

Body waves

Surface waves

Front 39

What are body waves?

Back 39

Waves that travel through the earths inner layers

Front 40

What are surface waves?

Back 40

Waves that only move along the surface of the planet

Front 41

What are the two types of body waves?

Back 41

Primary waves

Secondary waves

Front 42

What are primary waves?

Back 42

Push waves, they can travel through liquid and solid

Front 43

What are secondary waves?

Back 43

Shear waves, can only travel through the surface

Front 44

What are the three types of surface waves?

Back 44

Longitudinal waves

Transverse waves

Love waves

Front 45

What are longitudinal waves?

Back 45

Up and down movement (like a worm)

Front 46

What are transverse waves?

Back 46

Side to side movement

Front 47

What are love waves?

Back 47

A combination of transverse and longitudinal waves in a circular motion

Front 48

How are earthquakes measured?

Back 48

Mercalli scale

Richter scale

Moment magnitude scale

Front 49

How does the mercalli scale work?

Back 49

12 point scale that measures the intensity of the impact of an earthquake on people and envitonemnt

Front 50

What are the advantages and disadvantages of the mercalli scale?

Back 50

Advantage - Useful for people to measure the actual damage rather than magnitude

Disadvantage - not scientifically accurate, it's based on subjective observation.

Front 51

What is the Richter scale?

Back 51

A logarithmic scale measuring the magnitude or energy released of an earthquake based on seismograph readings

Front 52

What are the advantages and disadvantages of the Richter scale?

Back 52

Advantages - accurate scientific measurement useful for comparison

Disadvantages - not useful for people to know how deadly an upcoming earthquake is if predicted

Front 53

What is the moment magnitude scale?

Back 53

Takes in both previous measurements into account. Measures mostly magnitude but also takes in the intensity of the earthquake into account.

Front 54

How do seismometers work?

Back 54

Seismometers are placed in the ground and detect vibrations in the ground which are then displayed on seismographs

Front 55

What are the 3 P's?

Back 55

Prediction, prevention and protection

Front 56

What are the problems with predicting earthquakes?

Back 56

Very difficult, regions at risk can be identified but attempts to predict are unreliable

Front 57

Can we prevent an earthquake?

Back 57

No

Front 58

How can we protect people from an earthquake?

Back 58

Build earthquake proof buildings e.g. Transmerica pyramid in San Francisco

Educate people about earthquakes

Emergency planning - computer programmes in Japan alert people via media

Insurance - people urged to take insurance to cover loses as it can be very expensive

Aid - emergency aid sent after event e.g medical tents, food and rebuilding (long term)

Front 59

What is a tsunami?

Back 59

Any wave created by a geological stimulus e.g. an earthquake

Front 60

How is a tsunami generated by an earthquake?

Back 60

Underwater earthquakes cause the sea floor to become deformed, triggering a vertically displaced volume of water with waves moving outwards

Front 61

Port Au Prince, Haiti 2010 (LEDC)

Back 61

Caused by Caribbean plate moving against american plate at a transform plate boundary

Impacts:

Quarter of a million died

Thousands of buildings collapsed

Prison destroyed leading to criminals escaping

Cholera outbreak

Forced mass migration

1.2 million homeless

Responses:

Only 1 ambulance service run by a volunteer

No international aid, security concernsq

Armed forces and military arrived as they anticipated violence

Global relief effort people relocated to site with tents

Shortage of drinking wager. Government stopped some aid arriving at the airport

Front 62

Japan tsunami -March 2011 (MEDC)

Back 62

Cause: 9.0 on MMS

Impacts:

Earthquakes so massive it lower coastline by 1 meter

20,000 dead

Over 100,000 buildings destroyed

Fukushima nuclear plant overheated. Releasing radioactive substances leaving 35,000 homes uninhabitable

Front 63

Indian Ocean Tsunami - December 2004 (LEDC)

Back 63

No warning system, no preparation (barely any)

Causes:

plate subducting under Pacific plate

9.2 earthquake

35 meter high waves

Epicentre just off Sumatra coast

Impacts:

14 countries affected all poor

280,000 dead

1,500 villages destroyed

2 million homeless

Deforestation of mangroves before tsunami, loss of natural defence

Responses:

60% of fishing industry destroyed

July 2006 DART system set up

Provided sanitation to help contain spread of disease

Medical and monetary aid given ($1 billion worldwide)

Rapid burial of bodies due to disease Food aid to 1.3 million people affected

Front 64

What is a natural hazard?

Back 64

A naturally occurring process or event that has the potential to affect people

Front 65

What is a natural disaster?

Back 65

A major natural hazard that causes significant social environmental and economic damage

Front 66

What are the primary effects of earthquakes?

Back 66

Ground Shaking

Crustal fracturing

Front 67

What are the secondary effects of earthquakes?

Back 67

Liquefaction

Landslides and avalanches e.g Nepal 2015 mount Everest

Tsunami e.g 2004 & 2011

Front 68

How are aftershocks caused?

Back 68

Aftershocks occur in ephemeral area of the original earthquake, and are a result of the Earth 'settling down' or readjusting along the part of the fault that slipped

Front 69

What are the primary hazards of volcanoes?

Back 69

Lava flows

Pyroclastic flows

Tephra and ash fall

Gas eruptions

Front 70

What are the secondary hazards of volcanoes?

Back 70

Lahars

Jökulhlaup - heat of a volcanic eruption can melt snow and ice in a glacier causing heavy and sudden floods.

Front 71

How do we measure volcanic eruptions?

Back 71

Volcanic Explosivity Index (VEI)

Front 72

How does the VEI scale work?

Back 72

Volcanos are categorised by around and height of volcanic material injected

How long the eruption lasts

Qualitative descriptive terms like gentle or explosive

Front 73

How can we predict a volcanic eruption?

Back 73

Seismometers - when a volcano is about to erupt it generates loads of small as the magma tries to break through the crust. Scientists can detect these on seismographs

Thermal imaging - when a volcano is about to erupt the magma is very close to the surface causing the ground temperature to increase. Scientists can use thermal imaging to detect this increase in temperature

Tiltmeter - as the magma moves inside the volcanoes it changes the slope and angle or tilt of the volcano

Front 74

How is a tsunami generated?

Back 74

When land is uplifted due to the earthquake the ocean is displaced. Waves begin to radiate out from the source in all directions. As the tsunami reaches shallow waters e.g. the coast the eaves begin to slow down and increase in height to produce high waves.

Front 75

What is the hazard risk formula?

Back 75

Risk = (Hazard x Vulnerability) divided by capability to cope

Front 76

What human factors affect vulnerability and resilience?

Back 76

Quality of existing infrastructure (Mexico 2017 bad infrastructure)

Existence of disaster preparedness plans

Efficiency of emergency services

Existence of public education

Level of corruption of government

Wealth affects people's ability for them to protect themselves

Quality of health care

Population density

Front 77

What is resilience?

Back 77

The ability to overcome a natural hazard

Front 78

What are the geophysical trends since 1960?

Back 78

Number of deaths increased

More people affected

More damage caused by tectonic events

Front 79

Why have geophysical disasters increased?

Back 79

Global population in 1960 = under 3 billion

Global population in 2016 = 7.3 billion

This increase in population has meant that even more people are living in poverty and are vulnerable.

Therefore more people occupy more hazardous spaces and there is an increase in population density in megacities like Mexico City

Front 80

What is a disaster hot spot?

Back 80

A disaster hotspot is when hydrometeorological and geophysical hazards strike a vulnerable population. For example, the Philippines

Front 81

What are hydrometeorological hazards?

Back 81

Natural hazards caused by climatic processes (including droughts, gloods, hurricanes and storms)

Front 82

What makes the Philippines a disaster hot spot?

Back 82

The Philippines sits across a major convergent plate boundary creating volcanoes, earthquakes and tsunamis

Northern and eastern coasts face the Pacific ( world's most tsunami prone ocean)

The Philippines lies within South East Asia's major typhoons belt

47 volcanoes 22 of which are active

Landslides are common due to a combination of steep typography high levels of deforestation and high rain fall.

Front 83

Why is the Philippines vulnerable?

Back 83

Fast growing population

High population density

Many of the country's poor live in coastal areas where sea surges flooding and tsunami are made worse by poorly constructed housing and infrastructure.

25% of population live in poverty

Front 84

What is the Hazard management cycle?

Back 84

The hazard management cycle is the mitigation and preparation before an event and the response and recovery after an event.

Front 85

What is the park model (hazard-response curve)

Back 85

The park hazard-response curve is a model that shows how a country or region might respond after a hazard event

Front 86

What is hazard mitigation?

Back 86

Strategies meant to avoid, delay or prevent hazard event like land use zoning, diverting lava flows, GIS mapping and hazard-resistant design and engineering

Front 87

What is hazard adaptation?

Back 87

Strategies designed to reduce the impacts of hazard events like high-tech monitoring, crisis mapping, modelling hazard impacts, public education and community preparedness.

Front 88

What is land-use zoning?

Back 88

Land-use zoning is the process in which local government planners regulate how land in a community may be used. In areas at risk from natural hazards land use zoning is an effective way to protect people and property. This was done by New Zealands government with Mount Taranaki

Front 89

What is GIS mapping?

Back 89

GIS mapping is used to identify the locations of highly populated areas, sizes of major towns and cities, areas affected by the earthquake and the locations of airports and airstrip and key evacuation routes. This was used in the Nepal earthquake 2015.

Front 90

What are the key players in managing loss after a tectonic event?

Back 90

Aid donors

Governments

Non governmental organizations

Communities