Topic 2: Tectonic Processes and Hazards Flashcards
(187 cards)
1
Q
Distribution of earthquakes?
A
- most EQ zones are found at or close to tectonic plate boundaries, often in clusters.
- 70% of all EQs are found in the ‘Ring of Fire’ in the Pacific Ocean.
- most powerful EQs are associated with convergent or conservative boundaries.
- Some EQs can occur along old fault lines and the weakness is reactivated, e.g. Church Stretton Fault in Shropshire.
- OFZ and CFZ
2
Q
What is the oceanic fracture zone (OFZ)?
A
- a belt of activity through the oceans along the mid-ocean ridges, coming ashore in Africa, the Red Sea, the Dead Sea rift and California.
3
Q
What is the continental fracture zone (CFZ)?
A
- a belt of activity following the mountain ranges from Spain through the Alps to the Middle East and the Himalayas.
4
Q
Causes of earthquakes?
A
- sudden release of energy which has been built up over time by stress as two plates move past each other.
5
Q
Distribution of volcanic eruptions?
A
- occur at or close to plate boundaries. This is due to the movement of plates at different speeds and directions causing collisions.
- also occur at volcanic hotspots, e.g. Hawaii as magma rises as plume.
- there are 500 active volcanoes in the world.
6
Q
Distribution of tsunami?
A
- 90% of tsunami occur within the Pacific Basin.
- most are generated at subduction zones (convergent boundaries) particularly the Japan-Taiwan island arc and South America.
7
Q
Causes of tsunami?
A
- occur or generated when a sub-marine earthquakes displaces the sea bed vertically as a result of movement along a fault line at the subduction zone.
- they can generate intense ground shaking damage followed by the damage of the tsunami.
8
Q
What are the different types of plate tectonics?
A
- convergent
- divergent
- conservative
9
Q
Types of conservative plage margins?
A
- two oceanic plates
- two continental plates
- one continental and one oceanic plate
10
Q
Continental and oceanic plates meeting - diagram?
A
- see flashcard
11
Q
Continental and oceanic plates colliding - description?
A
- when the plates collide, the oceanic plate slides under (subducts) the continental plate into the mantle and melts.
- deep ocean trenches mark the oceanic plate starts to sink beneath the continental plate.
- the subduction also leads to the formation of fold mountains. Since the plates are constantly moving, most fold mountains will continue to grow.
- the friction created between the plates causes intermediate and deep earthquake in the Benioff zone.
- volcanic eruptions are also generated - magma created by melting oceanic plate pushes up through faults in the continental crust to reach the surface.
12
Q
Continental and oceanic plates colliding - example?
A
- Mount Fuji (Japan)
13
Q
Two oceanic plates colliding diagram?
A
- see flashcard
14
Q
Two oceanic plates collision - description?
A
- when two oceanic plates collide, one plate (denser or faster) is subducted beneath the other.
- deep ocean trenches form when subduction occurs, and the subducted plate then melts - creating magma, which rises up from the Benioff zone to form underwater volcanoes.
- over millions of years the volcanoes rise above sea level to form separate island volcanoes, usually found in curved lines called island arcs.
- the subduction also produced shallow-to-deep focus earthquake.
15
Q
Example of two oceanic plates colliding?
A
- 2004 Indian Ocean tsunami - Indian plate sinking underneath the Burma plate (a part of the Eurasian plate)
16
Q
Two continental plates colliding - diagram?
A
- see flashcard
17
Q
- two continental plates colliding - description?
A
- when two continental plates meet, a collision margin occurs. As both plates have about the same density, and are less dense than the athenosphere beneath them, neither plate is subducted.
- instead they collide and sediments between them are crumpled and forced up to form high mountains - e.g. the Himalayas.
- however there can be some subduction such as Nepal earthquake, caused when compressed (therefore denser) sediments result in plate subduction beneath them.
- there is no volcanic activity, but any earthquakes are likely to have a shallow-focus increasing their severity.
18
Q
Divergent plate margin - diagram?
A
- see flashcard
19
Q
Divergent plate margin - description?
A
- two plates are moving apart (diverging) leading to the formation of new crust. In oceans this divergence forms mid-ocean ridges, and on continents it forms rift valleys.
20
Q
Mid-ocean ridges?
A
- mid-ocean dishes of underwater mountains extend for over 60,000km across the world’s ocean floors.
- regular breaks (transform faults) cut across the ridges as they spread at different rates.
- regular volcanic eruptions - create submarine volcanoes, along the ridges, some of which grow above sea level to create new islands such as Iceland on the Mid-Atlantic Ridge.
21
Q
Rift valleys?
A
- when plates move apart on continents, the crust stretches and breaks into sets of parallel cracks (faults)
- the land between these faults then collapses, forming steep-sided valleys (rift valleys). E.g. Great Rift Valley - Zambia.
22
Q
Conservative plate margin - diagram?
A
- see flashcard.
23
Q
Conservative plate margin - description:
A
- two plates slide past each other, forming a conservative plate margin. This results in a major break in the crust between them as they move.
- the break is called a fault, and where it occurs on a large scale is known as a transform fault, which affected a wider area. Although no crust is made or destroyed here (and no volcanic activity - no magma), this type of plate margin is tectonically very active - associated with powerful earthquakes.
- the two plates sometimes stuck as they move past each other, causing stress and pressure to build up, which is suddenly released as a strong shallow-focus earthquake.
24
Q
Conservative plate margin - example:
A
- San Andreas Fault in California, which has generated significant earthquakes.
25
Interplate earthquakes definition:
- caused by stresses within a plate.
- since plates move over a spherical surfaces, zones of weaknesses are created.
- earthquakes can happen along these zones of weakness.
- not all EQs occur at plate boundaries, some are known as intra-plate EQs and occur in the middle of the plate.
- although it isn't sure why this happens. It is thought that it is due to stresses in ancient faults causing them to be active again.
- due to there being no well-defined pattern it is harder to predict them.
26
Volcanic hotspot definition:
- there is a plume rising under the surface which creates a hotspot on the surface.
- over millions of years magma has been carried and created land.
- e.g. Hawaii
27
Properties of magma - convergent boundaries:
- Friction and pressure build up in the Benioff zone (the area within the subduction zone where most friction and pressure build up occurs) causes strong earthquakes
- Volcanic eruptions tend to be explosive as the magma is forcing its way to the surface
- These eruptions are often rhyolite lava:
- High gas content
- Low viscosity
- Lower temperature
28
Properties of magma - divergent boundaries:
- Earthquakes tend to be mild and shallow
- Eruptions tend to be small and effusive
- The eruptions are usually of basalt lava:
- Low gas content
- High viscosity
- Higher temperature
29
Properties of magma - transform boundaries:
Plates can stick causing a significant build up of pressure and powerful earthquakes
30
Diagram of the earth?
- see flashcard
- crust
- mantle: largest section, convection currents, partially liquid.
- outer core: high temperatures, gives the magnetic field. Molten (iron)
- inner core: solid, extremely hot (7000 degrees). Hotter than sun’s surface. Solid - iron and nickel.
31
Lithosphere definition:
- the solid layer from which tectonic plates are formed.
| - between the crust and upper mantle.
32
Athenosphere definition?
- (mantle) hot, weak, plastic layer which plates ‘float’ on - ‘porridge like’
33
The crust?
- forms the outer shell of the earth
- two types:
* oceanic: a think dense layer (6-10km) which lines the ocean floors
* continental: an older, thicker layer (usually 45-50km) which makes up the earth’s landmasses. It’s pense dense then oceanic crust.
34
The mantle?
- surrounds the core, and is the widest layer making up the Earth.
- the upper part is solid, but below it, the rock is semi-molten - forming the athenosphere (on which tectonic plates ‘float’
35
The core?
- found at the centre of the earth
- consists of two parts:
* outer core
* inner core
- inner core: at the very centre of the Earth, and the hottest part (about 6000 degrees); solid and mostly consists of iron; 2015 - seismic waves data suggested that the inner core has another distinct area at its centre (now called the inner inner core)
- outer core: which is semi-molten and mostly consists of liquid, iron and nickel; temperatures there range from 4500-6000 degrees.
36
Plate tectonic theory:
- the lithosphere is broken up into seven major and several minor parts (tectonic plates) which move relative to each other over the asthenosphere.
- it is this movement which causes earthquakes and volcanic eruptions.
- the movement of these plates is driven by processes such as
1) mantle convection
2) slab pull
3) subduction
4) seafloor spreading
37
What is mantle convection:
- is was long though that this was responsible for the movement of plates however this is less accepted.
- in MC heat produced by the decay of radioactive elements in the Earth's core heat up the lower mantle crating convection currents.
- these hot, liquid magma currents move in circles in the asthenosphere thus causing the plates to move.
38
What is slab pull?
- increasingly being seen as the major driving force for plate movement.
- newly-formed ocean crust at mid-ocean ridges becomes thicker and denser as it cools.
- this causes it to sink pulling the plate further down with it.
39
What is subduction?
- as new crust is being created in one place it is being destroyed in another - by subduction.
- as two oceanic plates move towards each other one subducts underneath the other and into the mantle where it melts in the subduction zone.
40
What is seafloor spreading?
- mid - ocean ridges or underwater mountains are formed when hot magma id forced up from the asthenosphere and hardens. This creates new oceanic curst.
- the ocean crust pushes the tectonic plates apart (seafloor spreading).
41
Paleomagnetism definition/what is it?
- the study of past changes in the Earth’s magnetic field (determine from rocks, sediments or archaeological records)
- at mid-ocean ridges scientists found the same pattern of magnetic direction on either side of the ridges (something that could only happen if new rock was being formed at the same time on both sides.
- the theory proved that new rock was being created.
- this was proved by testing ions in the rock to show polarity.
42
Natural hazard definition?
- a naturally occurring process or event that has potential to affect people.
43
Natural disaster definition:
- a major natural hazard that causes significant social, environmental and economic damage.
44
Vulnerability definition?
- the ability to anticipate, cope with, resist and recover from a natural hazard.
45
Plate tectonic theory timeline?
46
Earthquake formation diagram?
- see flashcard
47
How are earthquakes formed?
- earthquakes occur when rock fractures along fault lines.
- energy is released as seismic waves causing the ground to shake.
- the point inside the crust where the pressure is released from is called the hypocentre. If this is shallow then the earthquake can cause much more damage.
- the point of the surface directly above the hypocentre is called the epicentre. This is where the most damage occurs.
48
What are the different types of waves?
- primary waves
- secondary waves
- Rayleigh waves
- love waves
49
What are primary waves?
- arrive fast, first and move through solid rock and fluids (shake in backwards and forwards motion) and pushes and pulls (compressions) in the direction of travel.
- they’re only damaging in the most powerful earthquakes
50
What are secondary waves?
- slower than p-waves, only move through solid rock with up and down motion.
- do more damage than p-waves.
51
What are love waves?
- only travel through the surface of the crust, fastest of the surface waves and move from side to side (horizontal) as it moves forwards.
- largest wave but also slowest
52
What are the primary effects of earthquakes?
- things that happen as a direct result of earthquakes.
- e.g.
* ground shaking: causes bridges, building, roads and infrastructure to collapse, killing or injuring those nearby.
* crustal fracturing: when energy released during an earthquake causes the earth’s crust to crack.
53
What are the secondary effects of earthquakes?
- often cause as much or more damage than the initial shaking.
- e.g.
* liquefaction
* landslides/avalanches
* tsunamis
54
Liquefaction definition and it’s effect?
- takes place when loosely packed, waterlogged sediments at or near the ground surface lose their strength and becomes more liquid than solid - the subsoil loses its ability to support building foundations so buildings and roads tilt or sink in response to strong ground shaking.
- liquefaction occurring beneath buildings and other structures can cause major damage and makes rescue efforts more difficult.
55
What are landslides?
- landslide: the rapid movement of earth’s materials down a slope, the material’s ranging from huge boulders to soil.
- can have a number of causes, of which earthquakes are just one. The shock of the earthquakes may be sufficient to start the slide.
56
What are the secondary effects of tsunami?
- some underwater earthquakes generate tsunami that cause major problems for coastal areas.
57
1989 Loma Prieta earthquake case study?
- 17th October 1989 - 6.9 magnitude earthquake near San Francisco.
- sandy soil amplified the ground shaking - the damage experienced by buildings and other structures. The sandy soil also liquefaction - causing building to collapse.
- part of the two-level cypress - freeway collapsed. Drivers on the lower level were injured or killed.
- 67 earthquake-related deaths
58
What are aftershocks?
- other smaller earthquakes which may follow for weeks, months or years after an earthquake.
- they occur in general area of the original earthquake and are a result or the earth ‘settling down’ or readjusting along the fault.
- can cause additional damage - e.g. structures weakened by the initial earthquakes may collapse, injuring or killing people and hampering rescue efforts)
- some aftershocks are very dangerous - e.g. Christchurch earthquakes in 2011 - the aftershock caused more damage and loss of life than the initial 2010 earthquake.
59
What is the Moment Magnitude Scale (MMS)?
- measures earthquake magnitude
- generally preferred as it’s accurate and better at measuring large earthquakes
- measures the total en where released by an earthquake at the moment it occurs (seismic moment) using the
* size of the seismic wave
* amount of slippage or rock movement
* area of the fault surface broken by an earthquake
* resistance of the affected rock.
- the scale goes from 1 (smallest) and is informé but usually stops at 10. Thé scale is logarithmic - each number is 10 times the magnitude of the number before.
60
What is the Moderate Mercalli Intensity Scale (MMIS)?
- measures intensity
| - scale goes from 1 (hardly noticed) to 10 (catastrophic)
61
What is the Volcanic Explosivity Index:
- used to describe and compare volcanic eruptions.
- uses a scale from 0 (non-explosive) to 8 (extremely large).
- logarithmic scale - increases by a factor of 10 each time.
- factors to assign a number include:
+ how long the eruption lasts
+ qualitative descriptive terms
+ height and amount of volcanic material ejected (e.g. tephra + ash falls, etc)
62
What caused the Christchurch earthquake?
- February 2011
- shallow focus and shockwaves were amplified by nearby solid rock
- an upper soft layer, about 30km thick, slapped back onto the layer underneath, sending renewed vibrations back to the surface, exaggerating the liquefaction.
- in places, waterlogged silt and sand lost its strength and cohesion and behaviour like a fluid, including eruptions onto the surface as ‘sand volcanoes’. Buildings lost their firm foundations and could no longer be supported.
- Mercalli Intensity scale - VII
63
Christchurch earthquake - effects and solutions?
- 80% of CBD buildings were damaged and had to be demolished.
- many new buildings will have a grid of stone columns inserted - this stabilises the ground and redistributes the weight of a building, reducing the stress on the ground - reducing the risk of ejected sand.
- some new buildings will have base idolaters. This is where buildings are not constructed directly onto the ground but are on flexible bearings so they when the ground is moved by earthquakes waves the building does not move enough to cause significant damage or collapse.
- historic buildings needed reinforcing. This was done by adding steel - reinforced concrete walls within existing wall cavities, bracing floors and roofs with plywood diaphragms.
64
Volcanoes definition:
- openings in the earth’s crust through which lava, ash and gas erupt. They are closely associated with plate margins similar to earthquakes.
65
How are volcanoes measured?
- measured by the Volcanic Explosivity Index (VEI).
| - the VEI uses a scale from 0 (non-explosive) to 8 (extremely large) and each number increases by a factor of 10.
66
How can volcanoes be predicted?
- volcanoes can be predicted as scientists can use equipment placed on a volcano as well as remote equipment (e.g. satellite-based radar and GPS) which monitor a volcano for signs that it may erupt.
67
Signs that a volcano may erupt?
- small earthquakes: as the magma rises to the surface it breaks the rock, causing small earthquakes which scientists can detect on seismograms.
- changes to the surface to the volcano: as it pushes upwards; the magma builds pressure (causing the surface of the volcano to swell)
- changes to the ‘tilt’ of the volcano: as the magma moves inside the volcano, it changes the slope angle or ‘tilt’ of the volcano.
68
Volcano formation?
1) as tectonic plates move, pressure builds and hot magma and gases push up from the mantle to the Earth’s crust and erupt.
2) when the magma reaches the Earth’s surface, it’s called lava.
3) when lava cools, it forms rock, so a volcano continues to erupt over time, it gets bigger.
69
General volcano facts?
- more than 500 million people worldwide are at risk from hazards caused by volcanoes.
- over the past 300 years, approximately 260,000 people have died as a result of volcanic eruptions.
- today, about 1,900 volcanoes are considered to be active.
70
Volcanic eruption case study example?
- Eykafjallajökull
| - Montserrat
71
About Eyjafjallajökull?
- 14th April 2010
| - Iceland: ash cloud spread over Europe.
72
What are the impacts of Eyjafjallajökull?
- 100,000 commercial flights were cancelled worldwide.
- worldwide, airlines lost US$1.7 billion in revenue.
- over 10 million passengers around the world were stranded or unable to board flight either to or from Europe (or even via Europe).
- 30% of global airline capacity was cut - with European capacity cut by 75%.
- the European economy lost US$5 billion as a result of the disruption.
- KENYA: 20% of the economy is based an export to Europe. When flights were cancelled, Kenyan businesses were forced to dump tonnes of fresh veg and flowers (casting US$1.3 million a day in lost revenue).
- No injuries or deaths
- 700 people evacuated
- Flooding caused by ice melt
- Contamination of local water supply with fluoride
73
Montserrat eruption?
- Montserrat: part of an island arc in the Caribbean Sea where the Atlantic Plate subducts beneath the Caribbean plate.
- 18th July 1995 - the Soufrière Hills volcano in the south of the island began to erupt huge clouds of ash. Over the next 5 years the eruptions continued - with pyroclastic flows also affecting much of the island.
74
Montserrat today?
- volcano is still active and two-thirds of the island is still inhabitable.
- a volcanic observatory has been built in the south to monitor the volcano.
- new infrastructure have been built in the safer northern part of the island.
- Montserrat is now trying to rebuild its tourism industry.
75
What were the impacts of Montserrat eruption?
- dozens of people lost their lives, and more than 7000 moved to other countries (over half of the original 11,000 residents.
- unemployment rose as the island’s tourist industry collapsed.
- a lot of farmland was destroyed or abandoned, because it was too close to the volcano - severely affecting agriculture.
- 2/3s of all housings and 3/4s of the infrastructure; were destroyed.
- many young people no longer saw an economic future on the island and moved elsewhere.
- the capital, Plymouth, was destroyed. It contained all of the island’s main services (such as government offices and hospitals).
76
What is the structure of a composite volcano?
- see flashcard
77
What are the features of a volcano?
- ash cloud
- crater
- main vent
- secondary vent
- lava flow
- layers of rock
- magma chamber
- conduit
78
Ash cloud definition?
- a cloud formed above the volcano which can drift into the sky and fall back to earth.
79
Crater definition?
- the mouth of the volcano which surrounds the vent.
80
Main vent definition?
- the primary opening of the volcano which magma, rocks and gas escape from.
81
Secondary vent definition?
- another vent though which magma and other rocks and gases can flow out.
82
Lava flow definition?
- lava will flow down the side of the volcano.
83
Layers of rock definition?
- successive eruptions have led to layers of volcanic rock being built up over time.
84
Magma chamber definition?
- a pool of magma beneath the volcano.
85
Conduit definition?
- the underground passage through which magma flows from the chamber to the vent.
86
Different types of eruptions:
- plinian eruption
- palean eruption
- Vulcanian eruption
- Icelandic eruption
- Hawaiian eruption
- Strombolian eruption
87
Plinian eruptions?
- eruptions with a high rate of magma discharge, sustained for minutes to hours.
- they form a tall, connective eruption column or a mixture of gas, and rock particles, and can cause wide dispersion of ash.
88
Pelean eruptions?
- associated with explosive outbursts that generate pyroclastic flows, dense mixtures of hot, volcanic fragments and gas.
- named for the eruption of Mount Pelée on the Caribbean island (1902).
89
Vulcanian eruptions?
- small to moderate eruptions, lasting seconds to minutes.
| - ash columns can be 20km in height, and lava blocks and bombs may be ejected from the vent.
90
Icelandic eruptions?
- characterised by diffusions of molten basaltic lava that flow from long, parallel fissures.
91
Strombolian volcano?
- the least violent types of explosive eruptions.
| - have explosions causing a shower of lava fragments.
92
Hawaiian eruptions?
- the least violent types of explosive eruptions.
| - fire mountains and lava flows.
93
What are the impacts of volcanic eruptions?
- primary impacts: volcanic gas; lava flows; trepha/ash falls; pyroclastic flows
- secondary impacts: jökulhlaup; lahars
94
What is volcanic gas?
- steam, sometimes containing other gases, escaped from geothermically active areas and can be seen in the form of geysers/fumaroles.
- these gases include water vapour (80%), carbon dioxide and sulphur dioxide.
- once in the air, gases can travel for 1000s of km.
- magma contains gases that are released into the atmosphere during a volcanic eruption.
- volcanic gas leads to heavy rainfall events.
95
What are lava flows?
- lava flows: streams of lava that have erupted from a volcano onto the Earth’s surface.
- they’re very hot (1170 degrees) and can take years to cool completely.
- generally not a threat to humans, because most of them move slowly so people can easily get out of the way. Although they can destroy many things - causing problems to many.
- buildings may be burnt and covered (e.g. Hawaii)
- the lava associated with composite cones ate andesitic and more viscous and flow more slowly (e.g. Mount Etna).
96
What ate tephra/ash clouds?
- tephra: pieces of volcanic rock and ash that blast into the air during volcanic eruptions.
- smaller pieces (ash) can travel 1000s of km while larger pieces tend to fall near the volcano, where they can chase injury or death. Can also damage structures.
- there are now a munger of Volcanic Ash Advisory Centres around the world monitoring ash clouds.
- roofs may collapse under the weight, engines may get clogged up or stop working. Can disrupt flight paths of aeroplanes - potential failures of jet engines.
- ash falls can he very disruptive - where the gas lands, it covers everything / causing poor visibility and slippery roads.
97
What are pyroclastic flows?
98
What are jökulhlaups?
- floods caused by a sudden release of water and rocks when glacial ice is melted by the eruption
99
What are lahars?
- a mixture of rocks, mud and water which flow down the volcano. They are fast flowing and destroy everything in their path
100
What are tsunami?
- tsunami: a series of larger-than-normal waves, which are usually caused by volcanic eruptions or underwater earthquakes.
- they tend to occur along plate boundaries - particularly the Pacific’s Basin’s ‘Ring of Fire’
- smaller tsunami occur almost every day, with little effect, but large tsunami can cause many deaths and widespread destruction.
101
Formation of a tsunami?
1) underwater movement (volcanic eruption, landslides or earthquakes) displaces water.
2) the displaced water (water column) is forced vertically upwards.
3) the water moves outwards in every direction as a series of waves.
4) in open water, tsunami can love extremely fast (over 600mph)
5) in open watered tsunami are difficult to sooty and don’t have a high amplitude.
6) as it moves towards the shore, friction on the seabed slows the wave down.
7) the water gets shallower so height of the tsunami increases as the water is forced into smaller areas.
8) the tsunami hits the coastline as a series of waves (not one).
9) the tsunami will move inland and keep travelling until it runs out of energy.
102
What are the impact of tsunami?
- large tsunami can travel for several miles - sweeping away buildings, tress, bridges and people.
- they also wash away the soil - undermining the foundations of buildings, bridges, and roads, uprooting trees and destroying farmland.
- tsunami can completely change the landscape. Small islands are often totally destroyed.
- most tsunami-related deaths are from drowning but many are killed or injured by large debris or collapsing buildings.
103
What was the 2004 Indian Ocean tsunami?
- caused by an earthquake in Indonesia which was estimated at a magnitude of 9.0 - 9.3.
- thrust heaved the floor of the Indian Ocean to Indonesia by about 15 metres and sent out shock waves. This then radiated out in a series of ripple waves.
- waves that struck coastline near Banda Ache were nearly 17 metres high.
- 12 countries were affected - from Indonesia to South Africa.
- five million were affected, nearly 300,000 died and 1.7 were left homeless.
104
The nature of the Indian Ocean tsunami (2004)?
- the earthquake that caused the tsunami was especially huge.
- the epicentre was close to some densely populated coastal communities, which had no time to react to the tsunami rapid arrival within minutes.
- there were no early warning systems in place in the Indian Ocean.
- the low-lying coastlines of many Indian Ocean countries and islands meant that the tsunami waves were able to travel several kmp/h inland.
- many of the countries in the region were LICs. They did not have the resources to spend on tsunami protection.
105
social impacts of the Indian Ocean tsunami (2004)?
- coastal settlements were devastated:
* in some areas, 70% of villagers were killed
* in Sumatra - 1500 villages were destroyed completely.
- infrastructure was destroyed, e.g. The Andaman and Nicobar islands were all but cut off as all jetties were washed away.
106
economic impacts of 2004 tsunami:
- economies were devastated, especially fishing, tourism and agriculture:
* Sri Lanka - more than 60% of the fishing fleet and industrial infrastructure was destroyed.
* Thailand - tourism industry lost about US$ 25 million a month, and 120,000 workers lost their jobs.
- overall economic cost came to $10 billion.
107
environmental impacts of 2004 tsunami:
- ecosystems were destroyed/severely damaged
- freshwater supplies/agricultural soil were contaminated by salt water
- most vegetation and topsoil was removed up to 800 metres inland.
108
Vulnerability definition:
- the ability to anticipate, cope with, resist and recover from a natural hazard.
109
Resilience definition:
- the ability to protect lives, livelihoods and infrastructure from destruction, and to restore areas after a natural hazard had occurred.
110
Hazard event definition:
- a natural hazard (e.g. earthquake, volcanic eruption or tsunami)
111
What is the pressure and release (PAR) model?
- shows how disasters are produced when natural hazards affect vulnerable people.
- a disaster occurs when two forces (socioeconomic pressures and physical pressure) collide. The ‘high pressure’ applied to the situation results in a sharp ‘release’ of the pressure.
112
Pressure and release (PAR) model diagram?
- see flashcard.
113
Root causes - PAR model:
- limited access to:
* power
* structures
* resources
- ideologies:
* political systems
* economical systems
114
Dynamic pressures:
- lack of:
* appropriate skills
* training
* local investment
* ethical standards in public life.
- macro-forces:
* rapid population change
* rapid urbanisation
* deforestation
* arms expenditure
* debt repayment schedules
115
Unsafe conditions:
- fragile physical environment
- fragile local economy
- vulnerable society
- public actions
116
Natural hazards:
- volcanic eruptions
- earthquakes
- flooding
- drought
- storms
- landslides
- pests of diseases
117
PAR model: Root causes - Haiti:
- Haiti were in severe debt to US, German and French banks. Therefore the little money was spent repaying debts rather than improving infrastructure.
- 30-40% of government budget came from foreign aid.
- 8% of the population lived below poverty line <$2 a day.
- extensive corruption within the Haitian government.
118
PAR model: dynamic pressures - Haiti:
- lack of:
+ effective education systems
+ disaster management systems
+ disaster preparedness systems
+ urban planning to control where and how buildings were constructed.
- macroforces:
+ rapid urbanisation - resulted in vulnerable slum-like housing
+ high population density - Port-au-Prince (306 per square kilometre.)
119
PAR model: unsafe conditions - Haiti:
- soft soil, which buildings were built on, amplified seismic waves - increasing ground shaking and damage.
- before EQ: 39% had access to safe water and 24% to sanitation.
- low GDP of $1300 meant infrastructure was constructed cheaply and quickly, which resulted in poor buildings.
-0 a lot of illegal housing was built in unsafe areas - e.g. hillsides.
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Hazard risk equation:
- risk (R) = hazard (H) x vulnerability (V) / capacity to cope.
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Hazard:
- near a volcano which is active - e.g. Mount Fuji.
| - proximity to a plate boundary - e.g. in Japan.
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Vulnerability:
- people in lower income areas may not be able to afford resources, e.g. first aid kits.
- some areas aren’t very accessible by road - rescue and aid can be delayed, e.g. Haiti EQ.
- people may not be well educated, meaning they are less aware of the risks and protection.
- communities with poor healthcare ate less likely to be able to cope with disease spread in hazards - e.g. water borne diseases in flood water.
- poor quality housing is likely to fall over in an EQ, trapping people and causing high numbers of deaths.
- high population density can lead to more people in a small area being affected, which makes recovery difficult.
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Capacity to cope?
- public education and drills can help people to be prepared for what to do in response to a hazard event - e.g. disaster preparedness day in Japan.
- government corruption between officials and business influences how resources are used.
- some emergency services can be mote or less effective in rescue efforts.
- building codes and regulations have been enforced so buildings are safe and good quality.
- people have enough money to help protect themselves in advance, e.g. quality buildings, first aid kits.
- developed communication systems can allow governments to inform people of some hazards in advance.
- the government have disaster plans in place meaning they can quickly respond and recover.
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EQ case study examples?
- Haiti EQ
- China EQ
- Japan EQ
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Haiti EQ - context?
- HDI: 0.510
- literacy rate: 61%
- life expectancy: 64
- doctors per 1000: 0.234
- GNI total: $3.4 billion
- GNI per capita: $1,330
- poorest country in the western hemisphere
- high rate of government corruption
- high population density
- weak infrastructure
- low lying coastline
- exposed to many disasters, e.g. droughts, floods, landslides
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Haiti EQ - causes?
- 12th Jan 2010
- 7 on the Richter scale
- caused by the movement in the Enriquillo - Plaintain Garden fault system in the south.
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Haiti EQ - impacts?
- 3 million people were affected
- over 220,000 deaths
- 300,000 injured
- 1.3 million people made homeless
- several hospitals collapsed
- airport and port damaged
- 30,000 commercial buildings collapsed/businesses destroyed.
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Haiti EQ - management?
- shelter: over 300,000 people
- provided tool kits/seeds to farmers to help them recover
- water supply improved for many
- over 100,000 people received information on how to cope with future disasters
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China EQ - context?
- HDI: 0.761
- literacy rate: 97%
- life expectancy: 76.9
- doctors per 1000: 1.98
- GNI total: $24.11 trillion
- GNI per capita: $10,610
- huge regional inequalities
- life expectancy, literacy rate (etc) ate much lower in inland regions of China
- mountain areas have poor infrastructure and are quite inaccessible
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China EQ - causes?
- 12th May 2008 - magnitude of 7.9 struck Sichuan (SW China) 50 miles trom Chengdu.
- shallow earthquake - only 19km under the surface
- collision plate boundary (Indian plate moving north)
- ground uplift of up to 9m occurred in some areas.
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China EQ - impacts?
- over 45.5 million people in ten provinces and regions were affected (5 million were made homeless)
- earthquake caused landslides - led to a 1/4 of the earthquake-related deaths - over 200 response workers
- 1000s of schools fell down (killing 5335 children) while properly built government buildings remained standing
- 87,000 people were killed or missing (7th highest death toll)
- economic loss of $191 million
- 370,000 people sustained injuries - mostly from fallen debris
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China EQ - management?
- 97% of the planned 29,704 reconstruction projects in the region had started
- 99% of the 196,000 farmhouse destroyed in the EQ had been rebuilt
- a total if 216 transport projects (e.g. highways, main roads, railways and airports) were under construction it had been completed
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China EQ - government management?
within hours:
- over 130,000 soldiers and relief workers were sent to affected areas
- medical services were quickly restored, which helped to avoid the outbreaks of disease (like Haiti)
- people in danger from landslides were safely located.
- government pledged US$10 billion for rebuilding works and banks wrote off the debts for those with no insurance.
- within two weeks temporary homes, roads and bridges were being built
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Japan EQ - context?
- HDI: 0.919
- literacy rate: 99%
- life expectancy: 84.4
- doctors per 1000: 2.412
- GNI total: $5.5 trillion
- GNI per capita: $41,580
- disaster response find - $4.5 trillion yen
* early warning systems which communicate to people immediately.
* training for disaster response - disaster response in schools (trained by the military)
- tectonically vulnerable - on a meeting point of three earthquakes
- high population density at the coast - 2/3 of Japan is mountains or forest
- 35 million people over the age of 70
- population is inland
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Japan EQ - causes?
- 11th March 2011, a magnitude of 9.0 earthquake struck under the Pacific Ocean 100km east of Sendai on the eastern coast of the Japanese island of Honshu
- waves reached up to 10km inland
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Japan EQ - impacts?
- Fukushima Daiichi Nuclear power plant was severely damaged releasing dangerous levels of radioactivity - 47,000 people had to he evacuated
- risk of flu and disease spreading between the elderly and weak was huge
- within 10 days, an estimated 452,000 people were living in evacuation facilities
- damage to roads, railways and airports severely impeded transport following the disaster
- only emergency vehicles were allowed to use roads - preventing food supplies, fuel and other aid from being driven from Tokyo
- heating and other services were cut off
- 15, 853 deaths
- 6,023 people injured
- 330,000 people homeless
- Over 300,000 buildings destroyed
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Japan EQ - management?
- within 24 hours, 110,000 defence troops had been mobilised
- all radio and TV stations switched to official coverage, which told people what was happening and what they should do.
- the Bank of Japan gave US$183 billion to Japanese banks so they could afford to keep operating
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What are hazard profiles?
- a diagram which shows the main features of different hazards
- we use then to display one hazard or multiple , which allows us to compare them directly.
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Why are hazard profiles used?
- governments can use them to help develop disaster plans
- certain factors such as rapid onset, might indicate that an early warning system is needed to allow the maximum time for evacuation/management
- give a good visual way for us to compare disasters without using a vast amount of statistics
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Haiti EQ HP?
- see flashcard
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China EQ HP?
- see flashcard
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Japan EQ HP?
- see flashcard
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What is the Hazard Management Cycle (HMC)?
- continuous 4-cycle stage
- different activities occur at each stage but there is also a great deal of overlap and linking between stages
- involves free players:
* governments at all levels - local, regional, national
* international organisations
* businesses
* community groups are involved in emergency planning
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Hazard management processes?
- mitigation
- preparation
- response
- recovery
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Mitigation definition?
- preventing hazard events or minimising their effects
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Preparation definition?
- prepare to deal with a hazard event
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Response definition?
- responding effectively to hazard event
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Recovery definition?
- getting back to normal
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Mitigation focus?
- identifying potential natural hazards and taking steps to reduce their impact
- main aim to reduce the loss of life and property (largely by helping communities to become less vulnerable
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Mitigation actions?
- zoning and land-use planning
- developing and enforcing building codes
- building protective structures (e.g. sea defence walls)
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Preparation focus?
- minimising loss of life and property, and facilitating the response and recovery phases
- many activities are developed and implemented by emergency planners in both governments and aid organisations
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Preparation actions?
- developing preparedness plans
- raising public awareness (e.g. holding EQ drills)
- developing early warning systems
- stockpiling aid equipment/supplies
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Response focus?
- coping with disaster
| - main aims are to save lives, protect property, make the affected areas safe, and reduce economic losses
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Response actions?
- search and rescue efforts
- evacuating people where needed
- restoring critical infrastructure (e.g. power and water supplies)
- ensuring that critical services continue (e.g. medical care and law enforcement)
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Recovery focus - short + long term?
short-term:
- focuses on people’s immediate needs, so it overlaps with the response phase
- may last for weeks
long-term:
- may continue for month or even years
- includes taking steps to reduce future vulnerability which overlaps with the mitigation phase and the cycle continues
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Recovery actions - long + short term?
short-term:
- providing food and temporary shelter
- providing essential health and safety services
- organising financial assistance
- restoring permanent power and water supplies
long-term:
- rebuilding homes and other structures
- repairing and rebuilding infrastructure
- re-opening schools and businesses
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What are the advantages of HMC?
- adaptable for all events
| - shows all management stages visibly
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What are the disadvantages of HMC?
- each process may be longer than others - may not all be the same length
- too generic
- no data/figures
- doesn’t specify economic development
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What is the park model?
- shows how countries or regions may respond after a hazard event
- used as a framework to understand the time dimensions of resilience, from the time the hazard strikes to when the community returns to normal operation
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Park model - what needs to be taken into consideration?
- hazards are inconsistent, e.g. magnitude of hazard, level of development
- all hazards have different impacts and responses. Haiti - short term whereas Montserrat - several years
- wealthier countries have different curves as they recover faster
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What are the advantages of the park model?
- shows where improvements can be made
- given countries a better view
- visually effective and east to interpret.
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What are the disadvantages of the park model?
- generalised model
| - no account of varying capacity to respond, some countries need more outside help than others
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Hazard mitigation/adaption definitions?
- Hazard mitigation: strategies meant to avoid, delay or prevent hazard events
- Hazard adaption: strategies designed to reduce the impacts of hazard events
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What are hazard mitigation strategies?
- land-use zoning
- diverting lava flows
- GIS mapping
- hazard-resistant design and engineering defences
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What are hazard adaption stategies?
- high-tech monitoring
- crisis mapping
- modelling hazard impacts
- public education
- community preparedness
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What is land-use zoning?
- land-use zoning: a process by which local governments regulate how land in a community may be used (e.g. as residential, industrial or recreational)
- it's an effective way to protect people and property in areas at risk from eruptions/tsunami
- any settlements tend to be limited, if they're allowed at all:
* certain types of structures and facilities will be prohibited (e.g. power stations - pose risks)
* some communities may be resettled (e.g. people who live along a coast may be moved inland)
* development in areas which provide natural protection will be limited
- land-use zoning is common in wealthy countries but less so in developing countries (Haiti). This is one reason why hazard evets often cause more deaths and destruction in developing countries.
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What is GIS mapping?
- can be used in all stages of the disaster management cycle (DMC). For example, to identify where evacuation routes should be placed (preparedness stage), or to help with rescue and recovery options (the response stage)
- combines information including: (Nepal 2015)
* the locations and very rough population sizes of major towns and cities
* the areas affected by the EQ
* the location of airports and airstrips
- the information helps aid agencies to identify the areas most affected by the EQ (or disaster) and then to find the nearest location where aircraft or helicopters carrying emergency supplies and relief workers could land.
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What is diverting lava flows?
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What are hazard-resistant design and engineering defences?
- collapsing buildings are one of the main causes of death and damage from tectonic hazards. Designing and constructing buildings that can withstand events more effectively is key to protecting lives and property.
- example: Pakistan - some hoses have been built from bales of straw held together by strong plastic netting (sandwiched between layers of plaster). During an EQ, the walls crack but don't collapse.
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examples of hazard-resistant buildings?
- new buildings and structures (bridges) can be designed to resist ground shaking during EQs.
- roofs of houses near volcanoes can be sloped to reduce the amount of ash that builds upon them thus reducing the risk of them collapsing under the weight.
- buildings at risk from tsunami can be elevated and also anchored to their foundations to stop them from floating away.
- existing buildings can be modified - called retrofitting - to make them safer. e.g. strengthening the foundations.
- protective structures (seawalls) can be built to stop or slow the impact of tsunami waves.
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What is high-tech monitoring?
- monitoring systems already allow some advanced warning of volcanic eruptions and tsunami to be given.
* GIS - helps to create hazard maps and manage hazards more effectively.
* early warning systems - use specific instruments to detect signs that a volcanic eruption or tsunami is about to occur. The relevant authorities then can be informed and rapid alerts issued to communities at risk.
* satellite-communication technology - helps to transmit the data from monitoring equipment, so that early warnings can be issued (e.g. the Indian Ocean Tsunami Warning System, by which scientific data collected from the seafloor is transmitted via satellite to ground stations every 15 seconds).
* mobile-phone technology - used to communicate rapid warnings and coordinate preparation activities. E.g. in Japan 2011 when seismographs detected p-waves off the northeast coast - the government sent out text messages (via mobile phone) warning of the EQ.
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What is crisis mapping?
- founded by members of Ushahidi (Haiti EQ)
- local people provide information, such as where people were trapped under rubble (or where food and water are needed), via social media sites and text messages
- These locations are then plotted onto maps by volunteers worldwide and placed online so that people with internet can see them
- rescue and aid workers began to use the maps to decide how, when and where to direct resources
- crisis mapping: uses crowd-sourced information (collected by volunteers in various locations) as well as satellite imagery and statistical models to accurately map areas struck by disaster.
- aid agencies are beginning to use crisis mapping before a disaster occurs (by pre-mapping vulnerable areas around the world).
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What is public education?
- can help reduce vulnerability and prevent hazards from becoming disasters. It helps people to understand what they can do to protect themselves before, during and after a hazard event.
- it includes:
* encouraging households and workplaces to create emergency preparedness kits
* providing effective educational materials, such as information on constructing buildings to withstand earthquakes.
* regularly practising emergency procedures (e.g. in Japan children practice EQ drills four times a year and the Japanese government also holds an annual Disaster Prevention Day), in which over 2 million people regularly participate.
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What is community preparedness and adaptation?
- community based preparedness is becoming an increasingly important part of hazard management.
- people living within a community at risk are often best placed to develop suitable preparedness plans and educate local residents. This is especially true in LICs where governments may not have the resources to invest fully in disaster planning or to reach all communities.
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Community preparedness activities?
- providing first aid courses
- organising evacuation drills
- creating a list of vulnerable people who may need special assistance (e.g. the elderly)
- local knowledge: 2004 Indian Ocean tsunami - the elders of Thailand's Moken tribe noticed unusual movements in the Bay of Bengal. They ordered villagers to run to the hilltop and as a result only one out of 200 villagers died.
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Key players in managing loss?
1) the role of donors
2) the role of non-governmental organisations (NGOs)
3) the role of insurance in hazard management
4) the role of communities in managing loss
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What is the role of aid donors?
- three stages:
* emergency aid - e.g. providing food, clean water, shelter
* short-term aid - e.g. restoring water supplies or providing temporary shelter
* long-term aid - e.g. reconstructing buildings and infrastructure, redeveloping the economy and managing programmes to reduce the risk of future disasters.
- organisations providing aid - NGIs, governments, international organisations (e.g. the UN)
- can be provided as cash, personnel, services or equipment
- can be distributed to the government of the affected country (which them uses it to manage the disaster recovery operation) or is controlled directly by aid agencies or foreign governments. E.g. Haiti 2010
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What is the role of NGOs?
- important in places where local governments are struggling to respond, or don't have the resources to do so. E.g. Haiti 2010
- they provide funds, co-ordinate search-and-rescue efforts, and help develop construction plans
- many NGOs are involved in all stages of the HMC and often remain in affected areas for years.
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NGOs - Pakistan EQ, 2005?
- responded immediately: over 500,000 tents and 6 million people blankets, safe water for over 700,000 people, food and clothing and emergency medical care
- short-term: more permanent shelters, re-established water supplies, roads rebuilt or re-routed
- recovery-phase: new schools, medical centres, and homes were built, community based disaster-risk reduction programmes were developed.
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What is the role of insurance in hazard management?
- natural disasters are expensive - in 2011 worldwide losses from EQs alone were US$54 billion
- insurance coverage provides individuals and businesses with the money needed to repair and rebuild. However, few people have insurance for tectonic hazards as more pressing economic needs are prioritised over events that may not happen
- Japan: governments and insurance companies work together to provide insurance for economic loss. However, these partnerships ate either unavailable or unaffordable in many developing countries.
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What is the role of communities in managing loss?
- communities are crucial in the immediate search-and-rescue efforts
- it can take days or weeks for aid to arrive so local people have to undertake the recovery steps themselves - e.g. creating shelters or cleaning debris to access roads
- community groups are also involved in long-term strategies for rebuilding and improving resilience
- example: after an EQ in Afghanistan (Oct 2015) villagers in mountain communities set up small groups to travel to the more remote areas to help with search and rescue
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The Philippines - background information:
- area: consists of 7107 islands, 25% bigger than UK.
- population: 2015 - 101 million
- wealth: GDP per capita = $7000 (MIC).
- landscape: mostly mountainous with coastal lowlands.
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Why is the Philippines physically vulnerable?
- sits across a major convergent plate boundary, so faces significant risks from both volcanoes and earthquakes.
- northern and eastern coasts face the Pacific Ocean (world's most tsunami-prone ocean).
- lies within South-East Asia's major typhoon belts. In most ears it experiences 15 typhoons ranging from 7-9. Also increases flooding and landslides.
- tropical monsoon climate - subject to heavy rainfall
- 47 volcanoes - 22 active. Over 30% of population live within 30km of a volcano.
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Why is the Philippines vulnerable - hum an factors?
- rapidly developing lower-middle-income country. Its development, and fast growing population, has led to rapid urbanisation ad a 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 the population live in poverty.
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What are the challenges of MHZ?
- one hazard or event can cause or increase other hazards.
- different hazards happening in a short amount of time can leave communities and the government having to deal with a new disaster at the same time as recovering from another. This drains resources and stretches the ability of emergency systems to respond.
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Philippines EQ- 2006:
- earthquake:
+ killed 15 people, injured 100 and damaged/destroyed 800 buildings
+ generated a local tsunami (3m high)
+ triggered landslides - created a flood that washed away houses.
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Philippines - three natural disasters in 2013:
- three disasters within three months.
- earthquake in October killing 223 people
- Typhoon Haiyan in November killing 6201 people
- floods from tropical depression in January 2014 killing 64 people.
