Tectonic Hazards Flashcards
Fault line
Crack/boundary between two tectonic plates
Hypocentre
Focus
The point at which the seismic waves are released
Epicentre
Directly above the hypo-centre. The point on the earths surface which has the most shaking and energy
Seismic waves
Ripples of energy released from the hypocentre
What are p waves?
They are primary waves that are caused by compression - pushing and pulling in the direction of travel
They are the fastest and arrive first
What are S waves?
Slower and only move through sold rocks, up and down movement
60% of the speed of p waves
Only through crust
What are L waves?
Love waves
From epicentre, only travel through crust, fastest surface wave
Moves from side to side as it moves forward
Causes the most damage due to longer wavelength and focus of energy at the surface
Moment magnitude scale
Measures the magnitude so the power by measuring how much energy is being released
Scale is logarithmic - each level is x10 more powerful
What are factors that explain the intensity of an earthquake?
Magnitude
Distance from the hypocentre
Bedrock and soil - pwaves travel fast through hard rock
What is the modified mercalli scale?
Reflects the effect and intensity of earthquake
Subjective scale
What does shaking depend on?
magnitude of quake
distance from epicentre
depth of focus (focal length), e.g. Haiti and
Christchurch
rock type (amplification) e.g. Haiti and
Christchurch.
Secondary hazards
Tsunami
Mudslides
Sink whole
Landslides
Primary hazards
Caused by the initial processes - ground shaking and crustal fracture
Secondary hazard
Are the side effects or the knock on impacts of primary hazards
What is liquefaction?
Loosely packed grains of soil are held together by friction, pores spaces fill with water
Shaking destabilises the soil by increasing the space between grains, with its structure lost the soil flows like a liquid
The soil then moves downslope which makes the foundation unsupported which causes buildings to sink and collapse
How do slope process and earthquake relate?
Mass movements
Occur naturally at coasts
Earthquakes with magnitude over 4 can increase likelihood as the shaking puts more stress on to the slope causing it to fail
What is the distribution of tectonic hazards?
Wide spread but mostly surrounding the ring of fire
- some hazards aren’t located due to hotspots
Intra plate
Hazard that occurs in the middle of a plate
Plate tectonic theory
The theory that the earths surface is a huge jigsaw of irregular slabs which are moving constantly
Inner core
6000 degrees
Inner - solid iron
Most dense
Outer core
Liquid nickel and iron - swirling around making magnetic swirls
4500-6000 degrees
Semi molten
Mantle
Widest layer
Asthenosphere = solid below this is molten where plates float
Crust
Continental plates are older, thicker but less dense
Oceanic are thin but more dense - basalt
Outer shell is solid rock
Convergent plate boundary - oc
Oceanic meets continental Subduction Mantle, melts Deep ocean trenches Fold mountains Frictional drag - intermediate and deep earthquakes in Benioff zone -volcanic eruptions
Convergent plate boundary - oo
Denser is subjected
deep ocean trenches form
subducted melts creating magma and rises through vent
= underwater volcanoes
Convergent plate boundary - cc
both plates have same density
less dense then the asthenosphere beneath them
neither plate sub ducted - collide and sediments crumpled and forced to form fold mountains
-Himalayas
Divergent
plates moving apart to form new crust
Oceans = forms mid ocean ridges
Continents = rift valleys
Conservative
two plates slide past each other creates major faults in crust very active and powerful earthquakes Cause stress and pressure build up Suddenly released as earthquake San Andreas
Intra plate - earthquakes
Earthquakes that occur in the interior of plates
occur along old fault lines which reactivate
collision of plates can also fracture the crust away from boundary
Intra plate - hotspots
Volcanic regions have underlying mantle lava that is hot
Position on earths surface is independant
Result from the upwelling of hot molten material from core
-high heat and low pressure at base of lithosphere enable melting of rock
-Magma rises through cracks in crust and erupts
-as the plate moves over the stationary hotspot, form chain of volcanic islands
Wegener plate tectonic theory
suggested that mountains formed when the edge of a drifting continent collided with another causing it to crumple and fold
-heat is produced by core due to radioactive decay
Harry Hess theory
Used sonar to survey the seafloor and discovered that it wasn’t flat and that there were mountain ranges in middle of ocean
- lead to the discovery that the ocean floor is getting older and closer to the coast
- newer crust must be getting produced by molten rock rising from inside of earth
Ridge push
Magma pushes up as earth splits and pushes crust outwards
Slab pull
Heavy weight of the crust pulls it downwards towards subduction zone at the edge of the ocean
Convection current
Creates frictional drag
radioactive decay or uranium
creates convection cells
seafloor spreading
Features of a tsunami
Long wavelengths - 150 - 1000km Low height - 0.5-5m until they reach shallow bed fast velocity series of waves Ring of fire most common 60% of wave energy reaches shore
As tsunami wave gets closer to shallow sea bed
friction of sea floor makes wave slow down but rise in height
High risk zones
East Asia, south of Asia
ring of fire
Formation of a tsunami
Subduction at the convergent margin
Elastic energy and tectonic strain builds up in Benioff zoner
Energy is released - elastic rebound and cause seabed tp thrust upwards
Shallow sea causes wave to slow down due to friction with sea bed but to grow in height
Factors affecting severity of tsunamis - human
- Quality of warning systems
- Degree of coastal development - pop size, tourism, industry
- Structural integrity of buildings to withstand wave
- Timing of the event
Factors affecting severity of tsunamis - physical
- Wave amplitude, amount of water displaced, velocity, distance travelled
- Physical geography of coast - water depth, gradient of shoreline
- ocean topography - deep water retain more energy
- degree of coastal eco-system buffer - mangroves, coral reefs, barrier islands
Liquefaction
where water rises during earthquakes causing rock to slide around more and cause buildings to collapse
Methods used to measure and research tsunamis
Recorder on seabed measure changes in pressure and can detect tsunamis as small as 1cm
- an acoustic link is transmits this data to a surface buoy
- data relayed to satellite
- satellite transmits data to ground stations
How do scientists predict tsunamis?
Systems use seismic sensors to detect undersea earthquakes
DART - Deep ocean assessment and reporting or tsunami
What is DART?
Uses seabed sensors and surface buoys to monitor changes in sea levels and pressure
when a wave is detected, the system sends the information via satellite to tsunami warning stations
-stations review and estimate the size and direction of the tsunami before warning risk areas
-Early warning systems
What is the tsunami intensity scale?
12 point scale
It is arranged according to a tsunami effects on humans, objects and damage to buildings
Rough correlation with tsunami wave heights
Which plate boundaries do volcanoes occur on?
Convergent - subduction creates friction
Divergent - magma rises as plates move apart
Hotspots- mantle plumes
Features of a volcano
Magma rises from the chamber through the crust via the conduit
Magma reaches the crater
Cloud of ash (tephra)
Layers of ash and lava make up the sides of the volcano
Fumaroles - holes in the ground that give out sulphur
Lahars, ash clouds, acid rain
Primary hazards of volcanoes tend to …
have a long geographical reach
-tend to kill less people than earthquakes but single events can be catastrophic
The more viscous the lava, the more…
explosive it is
Basaltic lava features
Hottest 1000 degrees Low in silica, water, gas and aluminium High in CO2 iron and magnesium -thin and runny -low viscosity as gases escape -eruptions are gentle and effusive
Basaltic lava - formation
By the melting of the mantle minerals (olivine) mostly from the upper zone but some from the core-mantle boundary
Basaltic lava - where is it found?
Ocean hotspots, mid-ocean ridges, shield volcanoes (Mauna Loa)
Andesitic lava - features
800 degrees
Intermediate silica, gas content, magnesium and iron
high water and hydrochloric acid
low SO2
-slow flow, intermediate viscosity traps gases
-eruption is violent and moderately explosive
Andesitic lava - formation
By sub-ducted oceanic plate melting and mixing with seawater, lithospheric mantle and continental rocks
Andesitic lava - where is it found?
Composite cone volcanoes - Chances Peak
Subduction zones
Rhyolitic lava - features
Coolest 650 degrees High silica, potassium, sodium, aluminium, gas content Low iron and magnesium -Flow is thick and stiff -High viscosity traps gases -Eruption is very violent, cataclysmic
Rhyolitic lava - formation
By melting of lithospheric mantle and sales of previously subjected plate
Rhyolitic lava - where is it found?
Super-volcanoes (Taupo), composite volcanoes
Composite cone volcano
Form from viscous lava (rhyolitic, andesitic)
Usually at subduction zones
Steep sided and formed of layers of lava and ash
More likler to have pyroclastic flows
Shield volcanoes
Formed from lava with low viscosity (basaltic)
Usually at ocean hotspots and mid ocean ridges
Less steep and very wide
Form from layers of lava
Primary hazards of volcanoes
Lava flows
Emissions of gases or steam (phreatic eruption)
Phreatic eruptions
Steam-driven explosions that occur when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits (for example, tephra and pyroclastic-flow deposits
Secondary hazards of volcanoes
Pyroclastic flows
Lahars
Jokulhlaups
Lava
- Molten rock/magma that has reached the Earths surface
- flows - depends on type
- Can outrun unless lava lake drains
- Burns and destroys settlements
Pyroclastic flows
Dense mixture of poisonous gas and tephra 1000 degrees 700km/h Explosive from composite volcanoes Turbulent, fast-moving ash clouds
Tephra
Molten and solid rock ejected from explosive eruptions
Ash
Small fragments
Travel higher and further
Transported by jet streams
Volcanic gas
Water vapour seeps from crack, produces further fumaroles and geysers
Water mixes with sulphur dioxide - produced acid rain and particles reflect solar radiation
Lahars
Rainwater mixes with ash to create fast moving mud flows
Jokulhlaups
Floodwater resulting from rapid melting of ice caps/glaciers (E15 Iceland)
How are volcanic eruptions measured?
VEI - volcanic explosively index
Measures the volume of products, eruption cloud height, qualitative observations
Open ended scale- largest in history 8
Logarithmic - with each interval on the scale representing a tenfold increase
PAR Model
Pressure and Release model
Risk equation
Risk = hazard x vulnerability
Risk reduction equation
Risk reduction = mitigation of hazard x reduction of vulnerability and increasing capacity to cope (resilience)
Risk
The probability of harm or loss taking place
Risk/damage threshold
the point at which risk leads to damage
Mitigation
Means finding new ways of being prepared for possible tectonic hazards so that their impacts can be prevented or reduced
How to reduce vulnerability?
Management policies by government
Educate and train
Develop warning and evacuation systems
Good infrastructure for housing
Where must the action to reduce vulnerability come from?
The government as individuals or communities may lack the capacity to make significant improvements on their own, only better governance can help reduce vulnerability
Root causes
Corrupt government
Lack of access to resources
Dynamic pressures
Lack of investment
Young, dependant population
Unsafe conditions
Close to capital
Bad infrastructure
low income
Diseases
Governance and political conditions that impact vulnerability
- enforcement of building codes and regulations - determine the safety and quality of buildings
- quality of existing infrastructure - can impact recovery speed
- disaster preparedness plans - how quickly and effectively response is
- emergency services
- communication systems - inform and coordinate people in advance
- public education and practised hazard responses
- level of corruption
Economic conditions that impact vulnerability
- level of wealth influences the ability to protect themselves and then recover from a natural hazard
- quality of housing - influences how able it is to withstand hazards
- income opportunities - lack of this can mean people can’t afford resources they need to prepare for hazard - can impact health and living standard
Social conditions that impact vulnerability
- health care - poor means more people will suffer from disease and are less able to cope and recover
- access to education - may be less aware of the risks of a hazard event and how to protect themselves
Physical and environmental conditions that impact vulnerability
- areas with a high population density tend to have more low-quality housing
- rapid urbanisation creates a need for more housing - most of which is built quickly and of poor quality
- the accessibility - how quickly rescuers and aid can arrive
Hazard profile
a way of comparing the physical processes and impacts that all hazards share
Why are hazard profiles useful?
help decision makers to identify and rank hazards that should be given the most attention rather than considering hazards separately
What are the characteristics of a hazards that have large risk?
- high magnitude, low frequency events - least expected
- rapid onset events with low spatial predictability - occur in a number of places and happen without warning
- regional areal extent - affecting large numbers of people in a wide range of locations
What are the factors on a hazard profile?
- magnitude
- speed of onset
- areal extent
- duration
- frequencey
- spatial predictability
Why is it difficult to compare 2 different hazards?
-they have varying impacts and spatial and temporal distributions
Governance
the sum of the many ways individuals and institutions manage common affairs
economic governance
decisions on countries economic activities and is relationship with other economies
-implications for equality, poverty and quality of life
political governance
decision making on policies including national disaster reduction planning.
-the nature of this process, the way it bring together the state, non and private sector players will determine the quality of the policies
Administrative governance
policy implementation requires a good governance at central and local levels
-for disaster reduction, it requires functioning enforcement of building codes, land use planning, environmental risk and human vulnerability monitoring and safety standards
Factors increasing risk
- population growth
- urbanisation and urban sprawl
- environnemental degradation
- very young or old population
- inadequate infrastructure
Factors mitigating risk
- warning and emergency response systems
- economic wealth
- government disaster assistance programmes
- scientific understanding
How does low human development increase vulnerability?
- more people lack basic needs of sufficient water and food
- housing is informally constructed with no regard for hazard resilience
- access to healthcare is poor
- education level is low - so hazard perception and risk awareness is low
Aspects of governance and disaster vulnerability
- meeting basic needs
- planning
- environmental management
- preparedness
- corruption
- open-ness
Case study - Egypt’s governance
- frequency of earthquakes are low
- this means that peoples perception of risk is poor
- the social and educational structures have not helped the distribution of knowledge and understanding either
- the Egyptian government produced a free booklet about earthquake disasters and how to prepare for them and distributed it through schools
- the emphasis was on emergency response
- enabled people to take action for themselves
What is gini coefficient?
a measure of corruption
What geographical factors influence the nature of tectonic hazards?
- population density - harder to evacuate
- degree of urbanisation - concentration of at-risk people
- isolation and accessibility -can slow the rescue relief effort
Hydrometeorological hazards
- caused by weather systems
- floods, storms, cyclones and drought
- more common over time due to global warming
Geophysical hazards
caused by weather systems
What kind of hazard is a landslide?
-tectonics and weather but classified as geophysical as they involve ground movement
What is the overall trend of natural disasters from 1960 - 2012?
- overall has increased
- from 1992 there was a drastic increase in the number of hazards
- since 1996, the number of hydro hazards has increased - due to climate change
- total reported has increased due to better technology
- higher density so more people at-risk
- changes to the environment - more urban areas
Why may graphs and data on hazard trends not be accurate?
- meaning of definitions vary - damage and disaster
- reported number of deaths might be inaccurate due to indirect deaths following the event (e.g., Cholera outbreak in Haiti)
- Mega-disasters can change trends
- political bias in reporting trends (e.g., Thailand post 2004 Tsunami, due to the impact on tourism)
- no single organisation is responsible for collecting data so methods vary in the collection of data
- difficult to collect data in remote areas - under reporting deaths and damage can occur
- this can also occur in densely populated areas of informal settlements where population is unknown (e.g., Dharavi slums, Mumbai)
Changing trends of death tolls
- overall fluctuates but without major events its decreasing
- more people are prepared and mitigating against hazards
- with a rising population, more people are likely to affected
Changing trend of affected people
- overall increase
- rising population living in hazardous area
Changing trends of economic damage
- overall increase in cost of damage
- growing population and economic growth
- more wealth to lose especially in more developed countries like Japan
What is a mega distaster and characteristics?
A high magnitude, high impact, infrequent disaster that affects several countries directly or indirectly.
- huge number of deaths
- high economic damage
- can’t predict
- impacts extend beyond one country
- regarded as high impact, low probability events
Mega disaster - 2004 Asian Tsunami
- affected 14 countries around the Indian Ocean
- economic loss and deaths
- largest in terms of areal extent
Mega disaster - 2011 Japanese Tsunami
- economic impacts had global consequences
- disruption to ports, factories and power supplies - impacted global car-production supply chain
Mega disaster - 2010 E15 eruption
- 20 European counties affected by total or partial closure of their airspace
- ash cloud led to closure as it would impact jet engines
Mega disasters significant on trade
-due to globalisation of production and supply chains, a mega disaster will have knock on impacts on is several countries, affecting their economies
Mega disasters significant on economic factors
- business -trade
- international aid
- tourism industry
- travel and aviation industry
- resources
- damaged crops
Mega disaster - Japan Tsunami global significance
-Flooding of Fukushima
- Fukushima flooded a depth of 5m shutting the emergency electrical supplies to generators that powered cooling supplies, B reactors melted and released radioactivity into the air and water in Pacific Ocean
- encouraged countries to think about safety of nuclear energy
- Germany decided to phase out its nuclear energy by 2022
- Italy and Switzerland confirmed their anti-nuclear power soon after
Mega disaster - Japan Tsunami global significance
- decline in Japan’s contribution to world industry, particularly with high tech products and vehicle manufacturing
- buildings that were destroyed in Japan released chemicals from the debris - debris carried throughout Northern Pacific and coast of North America with radioactive seawater
Mega disaster - Mount Pinatubo global significance
- damage to aeroplanes west of Philippines $100m damage- due to ash being deposited in the Indian Ocean and satellites tracked movement of ash at high altitude
- The SO2 aerosol cloud which circumnavigated the world several times in the lower stratosphere causing global decrease in temp from 1991 - 1993 by 0.6 degrees (global dimming)
Mega disaster - E15 global significance
- the distribution of the ash was across main flight paths and over airports - flights over Europe and North America were disrupted
- considerable disruption to tourism and business with total economic impacts estimated at over $3bn
- Perishable Kenyan agriculture products for the UK rotted in warehouses and workers were temporarily unemployed
- Vehicles didn’t reach European factories (BMW was down by 7000 vehicles in one week
Mega disaster -Indian Ocean Tsunami 2004 global significance
- affected countries around the Indian Ocean with deaths in Indonesia, Thailand and Sri Lanka
- Fatalities in 46 other countries due to tourism
What is a multiple hazard zone?
An area that is at risk from multiple types of hazards including tectonics and hydrometeorological
Why is important to identify multiple hazard zones?
- helps decision makers understand a regions hazards, to set priorities for action and to decide how to assign resources
- may get more support from international aid agencies as well as resources to help with disaster planning and prevention
Describe what multiple hazard zones are like
-are tectonically active and so earthquakes are common
-are geologically young with unstable mountain zones prone to landslides
-are often on major storm tracks either in the mid-latitudes or tropical cyclone tracks
-may suffer from global climate perturbations such as El
Nino
Examples of multiple hazard zones
The Philippines
Indonesia
Japan
Why is The Philippines considered to be a multiple hazard zone?
- sits across major convergent plate boundary so faces risk of volcanoes and earthquakes
- north and east coast faces the pacific the most tsunami prone ocean
- lies within South East Asia typhoon belt - flooding and landslides
- monsoon climate
- 47 volcanoes, 22 are active
- steep topography and high deforestation and high rainfall = landslides
How do human factors in The Philippines increase risk of multiple hazards?
- growing population - highly dense
- rapid urbanisation
- poverty - many people live in coastal areas -storms are worse due to poorly constructed infrastructure
- 25% live in poverty
Predict
using instruments to monitor and calculations to try and work out when and where a hazard event will occur
Protect
try to make buildings and infrastructure hazard proof
- cross bracing
- aseismic buildings
Prepare
make sure everyone knows what to do when it happens and have a plan for the short and long term recovery
Can earthquakes be predicted?
no
- only areas at high risk can be identified through risk forecasting
- areas that could suffer from severe ground shaking and liquefaction can be identified - this is used for land-use zoning purposes
- seismic gaps - areas that have not experienced an earthquake for some time are are overdue can point to areas of especially high risk
Can volcanic eruptions be predicted?
yes
- sophisticated monitoring equipment on volcanoes can measure changes as magma chambers fill and eruption nears
- tilt-metres and strain meters record volcanoes bulging as magma rises and seismometers record minor earthquakes indicating magma movement
- gas spectrometers analyse gas emissions which can point to increased eruption likelihood
Can tsunamis be predicted?
Partly
- an earthquake induced tsunami cannot be predicted
- however, seismometers can tell an earthquake has occurred and locate it, then ocean monitoring can detect tsunami in the the open sea
- this information can be relayed to coastal areas, which can be evacuated
Mount Pinatubo 1991 in the Philippines - multiple hazard zones
- during the eruption, the areas was struck by Typhoon Yunga
- heavy rain mobilised volcanic ash into destructive lahars
- landslides can be triggered by heavy rain on sloped previously weakened by earthquake tremors
hazard management
the process in which governments and other organisations work together to protect people from the natural hazards that threaten their communities
what is the aim of hazard management?
- avoid or reduce loss of life and property
- provide help to those affected
- ensure a rapid and effective recovery
Which players are involved with the hazard management cycle?
- governments (local, regional, national)
- international organisations
- businesses
- community groups
What are the four stages of the hazard management cycle?
- prevention and mitigation
- preparation
- response
- recovery
Hazard management cycle - mitigation and prevention - what are the aims?
- identifying potential natural hazards and taking steps to reduce their impact
- the main aim is to reduce the loss of life and property
- help communities become less vulnerable
Hazard management cycle - mitigation and prevention - What are the actions?
- zoning and land use planning
- developing and enforcing building codes
- building protective structures - tsunami sea defence walls
Hazard management cycle - mitigation and prevention - when does this take place?
-before and after hazard events
Hazard management cycle - preparedness - what are the aims?
- 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
Hazard management cycle - preparedness - what are the actions?
- developing preparedness plans
- developing warning systems
- creating evacuation routes
- stockpiling aid equipment and supplies
- raising public awareness (earthquake drills)
Hazard management cycle - preparedness - when does it take place?
-before hazard events
Hazard management cycle - response - what are the aims?
- coping with disaster
- the main aims are to save lives, protect property and make the affected areas safe and reduce economic losses
Hazard management cycle - response - what are the actions?
- search and rescue effort
- evacuating people where needed
- restoring critical infrastructure (power and water supplies)
- ensuring that critical services continue (medial care and law enforcement)
Hazard management cycle - response - when does it take place?
-During the hazard event
Hazard management cycle - recovery - what are the aims?
Short term - this focuses on peoples immediate needs, so it overlaps with the response phase.
Long term - this involves the same actions but continue for months and years. takes steps to reduce future vulnerability which overlaps with the mitigation phase and the cycle continues
Hazard management cycle - recovery - what are the actions? Short term
short-term -
- providing essential health and safety services
- restoring permanent power and water supplies
- re-establishing transportation routes
- providing food and temporary shelter
- organising financial assistance to help people rebuild their lives
Hazard management cycle - recovery - what are the actions? Long term
- rebuilding homes and other structures
- repairing and rebuilding infrastructure
- re-opening businesses and schools
Hazard management cycle - recovery - when does it take place?
-after hazard events
What does the recovery stage depend on?
- the magnitude of the disaster - bigger means longer
- development level - lower means longer, as poorer people are more severely affected
- governance, because well governed places will divert resources more effectively to recovery efforts
- external help- aid and financing to help the recovery effort
How is the importance of the recovery stage be shown?
Park’s model - the disaster response curve
What can be done to forecast hazards?
- probability is used to measure when an earthquake of a particular magnitude is likely to occur - large earthquakes happen less often 1 in 1000 year
- long-term forecasts are more reliable than short term
- based on data gathered from global seismic monitoring networks and historical records
- satellites monitor crust from space to look for signs of stress building
Why is it difficult for scientist to accurately predict?
- people measured Radon Gas, animal behaviour but didn’t work
- hypo-centres typically 15km under ground - as you go down everything changes
- temperature, rock type, pressure - can’t pinpoint which factor is effecting them
What is resilience?
ability to resist, cope with, adapt and recover from
What is the park hazard response model?
- used to show how resilience in the aftermath of a hazard event can vary in different countries
- model shows that a hazard will inevitably cause a deterioration in QOL and economic activity
- but the amount of disruption and time it takes to recover varies depending on the success of the relief, rehabilitation and reconstruction
What does the park hazard model show?
- the impacts of a hazard event change over time - depending on factors such as the size of the hazard, the development level of the areas affected and the amount of aid received
- all hazards have different impacts so their curves are different have different responses
- wealthier countries have very different curves than developing countries because they will be able to recover much faster
Rehabilitation and relief stage of park model
-relief and rehabilitation period often with outside help through national and international agencies
reconstruction stage of park model
- nature of recovery related to the:
- need to reduce vulnerability
- desire to increase self-resilience
- goal of restoring normality as soon as possible
What are the types of disaster modification?
- modify event
- modify vulnerability
- modify loss
Modify event
- before the hazard
- long term
- mitigate the impacts of the hazard by reducing its areal extent and effective magnitude
- use this as can’t predict earthquakes
How was Mount Pinatubo modified?
-draining crater lakes to reduce the risk of lahars
How was Ofunto Bay, Japan modified? (tsunami)
-by changing the offshore coastal environment
How was Glendales Jong, Indonesia modified? (tsunami)
-higher and stronger sea walls, mangrove forests - 70,000 trees were planted after 2004
How has New Zealand modified the events?
-GNS science use satellite and aircraft remote sensing data
(LIDAR - light detection and ranging)
(SAR - synthetic aperture radar)
-create 3D data for the Earth’s surface
Modify vulnerability
- before the hazard strikes
- short term
- get people out of the way of the hazard, or help them cope with its impacts by building resilience
- most effective
- can lead to complacency and lack of preparation
How did Japan modify vulnerability?
2011
-Japanese scientists had predicted a smaller earthquake than the tsunami in 2011
How did Japan modify vulnerability? Kobe earthquake in 1995
the group of Japanese experts responsible for predictions all reigned
Modify loss
- after the hazard strikes
- short/long term
- reduce the short and long term losses by acting to aid recovery and reconstruction
Modify the vulnerability - High tech scientific monitoring
what is it?
pros and cons?
- used to monitor volcano behaviour and predict eruptions
+in most cases, predicting an eruption Is possible
+warnings and evacuations save lives
-costly, so not all developing world volcanoes are monitored
-does not prevent property damage
Modify the vulnerability - community preparedness and education
what is it?
pros and cons?
-earthquake kits and preparation days, education in schools
+low cost often implemented by NGO’s
+can save lives through small actions
-doesn’t prevent property damage
-harder to implement in slated rural areas
Modify the vulnerability - adaption
what is it?
pros and cons?
-moving out of harm’s way and relocation to a safe area
+would save both lives and property
-high population densities prevent it
-disrupts peoples traditional homes and traditions
Modify the loss - short term emergency aid
-search and rescue followed by emergency food, water and shelter
+Reduces death toll by saving lives and keeping people alive until longer-term help arrives
-high costs and technical difficulties in isolated areas
-emergency services are limited and poorly equipped in developing countries
Modify the loss - long term aid
-reconstruction plans to rebuild an area and possibly improve resilience
+reconstruction can build in resilience through land use planning and better construction methods
-very high costs
-needs are very quickly forgotten by the media after the initial disaster
Modify the loss - insurance
-compensation given to people to replace their losses
+allows people to recover economically by paying for reconstruction
-doesn’t save lives
-few people are in the developing world have insurance
What is the cry wolf syndrome?
occurs when prediction and evaluations prove to be wrong, so that people are less likely to believe the next prediction and warning so therefore fail to evacuate
Hazard mitigation
strategies meant to avoid, delay or prevent hazard events (land use zoning, diverting lava flows, GIS mapping, hazard resistant design and engineering)
Hazard adaptaiton
strategies designed to reduce the impacts of hazard events (high-tech monitoring, crisis mapping, modelling hazard impacts, public education and community preparedness)
Examples of government hazard-mitigation strategies
- land use zoning
- diverting lava flows
- GIS mapping
- hazard resistant design and engineering defences
What is land use zoning?
a process by which local government planners regulate how land in a community may be used (residential, industrial, recreational)
Why is land use zoning helpful?
- in areas at risk from eruptions and tsunamis, land use zoning is an effective way to protect both people and property
- land use planner and other use hazard maps like this to make decisions about the appropriate use of land in each zone as well as for predatory tasks such as determining safe evacuation routes
In areas of high risk, what does land use zoning say?
- any settlements tends to be limited
- certain types of structures and facilities will be prohibited -such as those that pose a risk if damaged or those that are critical for. a community to function (hospitals)
- some communities may be resettled (people along a coast deemed to be at risk of tsunami may be moved inland to higher ground)
- development in areas which provide natural protection will be limited (coastal mangrove forests, which act as buffers and reduce the impact of tsunami waves)
Advantages of land use zoning
- low cost
- removes people from high-risk areas
Disadvantages of land use zoning
- prevents economic development on some high-value land (tourism)
- requires strict and enforced planning rules
What are the different methods of diverting lava flows?
- they are done to divert flows away from people and communities
- building barriers and digging channels to try divert the flows into a safer direction
Why is it difficult to divert lava flows?
- the path taken by lava is hard to predict - making it difficult to know where to build the walls or dig the channels
- the terrain has to be suitable (downward slop so the diverted lava can easily flow away)
- stopping the lava from flowing towards one community may push it towards another
Pros and cons of lava diverting
pros - diverts it out of harms way -relatively low cost cons -only works for low VEI basaltic lava -the majority of killer volcanoes are not basaltic lava
What is GIS mapping?
- can be used in all stages of the disaster management cycle
- to identify where evacuation routes should be placed or to help with rescue and recovery options
Why is GIS mapping useful?
this information can help aid agencies to identify the areas most affected by the earthquake and then to find the nearest location where aircraft or helicopters carrying emergency supplies and relief workers can land
What is hazard resistant design and engineering defences?
-designing and constructing buildings that can withstand hazard events more effectively is key to protecting lives and property
Different types of hazard resistant design and engineering defences
- new buildings and structures can be designed to resist ground shaking during earthquakes
- the roofs of houses built near volcanoes can be sloped to reduce the amount of ash that builds up on them - this can reduce the risk of them collapsing under the weight
- building at risk from tsunami can be elevated and also anchored to their foundations to stop them floating away
- existing buildings can be modifies (retrofitting) to make them safer by strengthening their foundations
- protective structures such as seawalls or retaining walls can be built to stop or slow the impact of tsunami waves and landslides
Who are important player of hazard resistant design and engineering defences
Engineers - they do a lot of research and study the impacts of tectonic events on structures and then developed ways to make them safer
Examples of hazard resistant design and engineering defences
- rolling weights on roof to counteract shock waves
- panels of marble and glass flexibly anchored to steel superstructure
- reinforced lift shafts with tensioned cables
- birdcage interlocking steel frame
- reinforced latticework foundations deep in bedrock
- rubber shock absorbers between foundations and super structure
- cross bracing
Pros and cons of hazard resistant design and engineering defences
pros
-widely used technology can prevent collapse
-protects both people and property
cons
-high costs for tall structures
-older buildings and low income homes are rarely protected
What are some tsunami defences, pros and cons?
-tsunami sea walls and breakwaters prevent waves travelling inland
+dramatically reduces damage
+provides a sense of security
-can be overtopped
-very high cost
-ugly and restrict use/ development at the coast
Sendai framework (2015-2030)
-says that emergency planners have a key role in reducing impacts of tectonic hazards
Targets for sendai framework to reduce
- disaster mortality
- number affected
- economic losses
Targets for sendai framework to increase
- number of disaster risk reduction strategies
- cooperation between developed and developing
- information flow to people
- number of warning systems
Priorities for action (Sendai Framework)
- understand disaster risk
- strengthen disaster risk governance
- invest to make places more resilient
- strengthen disaster preparedness and actions during recovery phase
How did planners modify Mount Etna eruption?
-Italian workmen attempt to stop Mount Etna’s lava flow using earth dams as diversions
How did planners modify Iceland eruption of Eldfell in 1973?
- Icelandic authorities got fishermen to spray Lava flows
- 43 pumps non-stop spraying seawater to cool volcano and to stop it from blocking the harbour entrance
How did planners modify Mount Pinatubo in 2001?
- volcanologists drain the crater lake if Mount Pinatubo in 2001 to the growth of lahars drowning villages
- 75m canal dug on side of crater lake
What is base isolation?
-putting flexible bearings or pads made from layers of rubber and lead between the buildings foundations and structure
What have Japan done to protect against tsunamis?
- offshore wave barriers
- 250 mile and 4 storey high walls
- £4.6bn cement barrier
- negative impact on marine life
- replanting mangrove forests to absorb wave energy - cut greenhouse emissions - £4m
What is the role of aid donors in managing loss?
-need aid to recover and rebuild
emergency aid - providing food, clean water, shelter
short-term aid - restoring water supplies, providing temporary shelter
longer term aid - reconstructing buildings and infrastructure, redeveloping the economy and managing programmes to reduce the impact of future disasters
What is the role of NGO’s in managing loss?
- important in disaster when the local government is struggling to respond ore doesn’t have the resources to
- they can provide funds, co-ordinate search and rescue efforts and help to develop reconstruction plans
What is the role of insurance in hazard management?
- insurance coverage can help communities to recover from disasters
- it provides individuals and businesses with the money they need to repair and rebuild
- many people in developing countries have no insurance
What is the role of communities in managing loss?
- they are crucial in the immediate search and rescue efforts
- in remote or isolated communities, it can take days or weeks for aid to arrive so local people have to undertake the recovery steps themselves (creating temporary shelters or clearing debris from access roads)
- community groups are also often involved in long-term strategies for rebuilding and improving resilience
