Tectonic Processes and Hazards Flashcards
Define natural hazard
They are a natural/geophysical event that has the potential to threaten both life and property.
Define disaster
This is when the natural hazard actually happens and harms people, the environment or the economy
Define vulnerability
How susceptible an area or population is to damage from natural hazard events
What are the factors that influence the vulnerability of a population?
- Population density
- Building quality
- Level of urbanisation
- Wealth
- Quality of emergency/ health services
- Level of education
- Level of corruption
What are the 4 stages of the hazard management cycle?
Response -> recovery -> mitigation -> preparedness
What are the stages of Park’s model (aka the disaster response curve)?
Preparation -> response -> reconstruction -> mitigation
What is the hazard risk equation?
Risk = (hazard x vulnerability)/capacity to cope
What are the headings under vulnerability in the PAR model?
- Root cause e.g. limited access to resources
- Dynamic pressures e.g. lack of education
- Unsafe conditions e.g. fragile economy
Define asthenosphere.
The part of the mantle below the lithosphere where rock is semi-molten.
Define Benioff zone.
The are where friction is created between colliding tectonic plates, resulting in intermediate and deep earthquakes.
Define collision boundary.
When two continental plates collide forming fold mountains as there is no subduction.
Define constructive boundary.
When two plates spread apart causing magma to be released and new land being made.
Define conservative bounday.
When plates move alongside each other in the same or different direction, causing friction to build.
Define convection.
Heat from the core makes magma in the mantle rise towards the crust. As the hot current nears the crust, it begins to cool and sink back towards the core. As the magma sinks, it drags the plates across the surface of the Earth.
What is the core?
The extremely hot centre of the Earth.
What is the crust (continental and oceanic)?
The thinnest chemical layer and the outer layer of the Earth.
Oceanic is denser, made of basalt and thinner while continental is less dense, made of granite and thicker.
What is Degg’s model?
Shows the interaction between hazards and human vulnerability.
Claims disasters only occur when a vulnerable population is exposed to a hazard
Define destructive boundaries.
When the denser oceanic crust sinks beneath the continental crust.
Define epicentre.
The point on the Earths surface directly above the focus of an earthquake.
Define the focus.
The point inside the Earths crust from which pressure is released when as earthquake occurs.
Define geophysical hazard.
A hazard caused by land processes on a large or local scale and include tectonic or geomorphological hazards.
Define governance.
The organisation that controls/oversees a country.
What is a hazard profile?
A diagram that shows the main characteristics of a tectonic hazard.
A single hazard could be plotted or several could be to compare events.
They can help governments develop disaster plans.
Define HILP
High impact Low probability.
Define hotspot.
Points within the middle of a tectonic plate where plumes of hot magma rise and erupt.
Define hydrometeorological hazard.
Natural hazards caused by climate processes (e.g. droughts, floods and storms)
Define intensity.
The measurable amount of a property e.g. force
Define jökulhlaups.
Glacial outburst floods.
Define lahar.
Volcanic mud slides.
Define lava.
Molten or partially molten rock.
Define land-use zoning.
A process by which local government regulates how land in a community may be used.
Define lithosphere.
The solid layer, made from the crust and upper mantle, from which tectonic plates form.
Define liquefaction.
When the violent shaking during an earthquake causes surface rocks to lose strength and become more liquid than solid.
Define logarithmic.
A count that goes up the same amount each time
Define a love wave.
The fastest surface wave, has the longest wavelength and moves side to side while going forward.
Define magma.
Extremely hot liquid & semi-liquid rock located in the mantle.
Define magnitude.
A number that characterises the relative size of a tectonic event.
Define mantle.
The second chemical layer of the Earth that is made of molten magma (iron, magnesium and periodite)q
Define mantle plume.
A rock upwelling from the mantle that is extremely hot. Causes most hot spots.
Define mega-disaster.
A natural disaster of immense magnitude or one that causes severe damage.
Characterised by 2000+ deaths or 200,000+ homeless etc,
What is the Mercalli scale?
A scale of earthquake intensity ranging from I to XII.
Define mesosphere.
The third mechanical layer of the earth. It is solid due to pressure.
Define mid-oceanic ridge.
When two oceanic plates move apart in the ocean.
Define moho.
The boundary between the crust and the mantle.
What is the moment magnitude scale.
A way to quantify an earthquake’s magnitude.
Define multiple hazard zone.
An area that is at high risk from multiple natural hazards.
Define ocean trench.
Long, narrow depressions on the seafloor as a result of tectonic activity at convergent plate boundaries.
Define palaeomagnetism.
The study of past changes in the Earths magnetic field.
What is the Park’s Model?
It shows how a country or region might respond after a hazard event.
What is the Pressure and Release Model (PAR)?
A tool used to work out how vulnerable a country is to hazards.
The ‘release’ idea represents the reduction of disaster via relieving pressure to reduce vulnerability
Define primary wave.
The fastest body wave which arrives first. It moves through rock and fluid in an accordion movement.
Define a pyroclastic flow.
A flow of tephra and volcanic rock
Define Rayleigh wave.
The slowest, last to arrive wave. Moves only through the crust. Responsible for the movement and shaking felt. Rolling movement.
Define resilience.
The ability to cope and recover
Define rheid.
Partially liquid.
Define ridge-push.
Where lava hardens between ridges push the plates apart.
Define risk.
The probability of a hazard occurring that leads to loss of life or livelihoods
Define sea floor spreading.
Mid-oceanic ridges form new crust when magma cools which pushes plates apart.
Define secondary wave.
The slowest main body wave that arrives second. It only moves through the solid rock and moves up and down.
Define seismic gap theory.
Predicting the magnitude of an earthquake via its frequency.
Define seismic wave.
A wave of energy that travels through the earth.
What is a seimometer?
Measures the movement of the ground to measure an earthquake/volcano
What is a shield volcano?
A short, effusive volcano with effusive explosions that are made only of lava.
Define slab-pull.
When newly formed oceanic crust sinks into the mantle, pulling the rest of the plate further down.
What is a stratovolcano?
A tall, violent volcano of infrequent eruptions made of ash and lava.
Define subduction.
The area in the mantle where a tectonic plate melts.
Define surface wave.
First surface wave that travels through the surface
Define tephra.
Solidified magma (sizes from ash to lava bombs)
Define tsunami.
A sequence of extreme waves due to water displacement.
What is the volcanic explosivity index (VEI)?
It measures the size of explosive volcano eruptions from 0 (non-explosive) to 8 (mega-colossal) and is logarithmic (every increase is by a factor of 10)
Several factors are measured:
- High or eruption column
- Amount of volcanic material
- Duration of explosion
What are some examples of volcanoes measured under VEI?
1 is a Hawaiian style small gentle eruption
5 is a very large eruption with a high eruption column from a composite cone volcano e.g. Mount St. Helens, 1980
The largest ever recorded only reached 8 on the VEI scale
Define volcano.
An opening in the crust that allows lava, ash and gases to escape from magma chamber allow.
Who was Alfred Wegener?
He came up with the Continental Drift Theory in 1912
What are the mechanical layers of the earth?
- Lithosphere
- Asthenosphere
- Mesosphere
- Outer Core
- Inner Core
What are the chemical layers of the earth?
- Crust
- Mantle
- Core
How does mantle convection work?
- Heat from the Earth’s core, caused by radioactive decay, rises to produce convection currents in the molten mantle.
- The lithosphere is broken up into fifteen tectonic plates which ‘float’ on the asthenosphere below.
- Mantle convection causes magma to move, causing the plates to move, bringing them into contact at plate boundaries
What is ridge push?
A plate tectonic process where rising magma in the asthenosphere diverges and pushes plates apart
What is slab pull?
A plate tectonic process where sinking magma, along with gravity, help drag plates down into the mantle.
What is subduction?
A plate tectonic process that is closely related to slab pull at destructive or convergent plate boundaries
What is sea floor spreading?
A plate tectonic process which occurs at constructive as a result of rising magma in the asthenosphere and creates mid-oceanic ridges, as the sea floor spreads apart.
What were the 6 sets of evidence of the Continental Drift Theory?
- Jigsaw Fit
- Geological Fit
- Tectonic Fit
- Glacial Deposits
- Fossil Evidence
- Climatology
What is jigsaw fit?
One set of evidence for the continental drift theory where several continents seem to have a jigsaw like fir, especially South America and Africa. This suggest they were once part of a supercontinent called Pangea.
What is geological fit?
One set of evidence for the continental drift theory where rocks of similar type, age, formation and structure occur in SE Brazil and South Africa. If you fit the continents together, the distribution matches. This means these rocks must have been under the same conditions at the same time in the same place.
What is tectonic fit?
One set of evidence for the continental drift theory where one set of mountains can correspond geologically with mountains on another continent, suggesting they were formed before the continents drifted apart.
What are fossil evidence?
One set of evidence for the continental drift theory where the fossils, bones or remains of extinct animals can be found in both Africa and South America, suggesting it lived there before they separated.
Who theorised sea-floor spreading and when?
Harry Hess in 1962
What is palaeomegnetism?
The process where magma cools during an underwater volcanic eruption and minerals align themselves along the Earths magnetic field. This field reverses periodically so over time rock would be aligned to different poles as this changes.
Through palaeomagnetism, it was discovered that there is symmetrical pattern of magnetic stripes on either side of the mid-oceanic ridges.
What are the three main types of plate boundary?
- Constructive/Divergent
- Destructive/Convergent
- Conservative/Transform
What happens at a constructive/divergent margin?
Plates are moving away from each other. At these ridges, rising magma creates new crust.
Shallow focus and low magnitude earthquakes and volcanic activity are found here.
What happens at a destructive/convergent margin?
Plates are moving towards each other. One plate is forced beneath the other and plate material is melted in the mantle.
At C-C, collisions occur and mountains are formed.
Both volcanic (explosive) and earthquake (shallow to deep with medium to high magnitudes) activity is found at O-C and O-O, but only earthquakes at C-C boundaries.
What happens at a conservative/transform margin?
Plates are sliding past each other. No lithosphere is created or subducted, no there is no volcanic activity.
There is extensive seismic activity with large magnitude, shallow earthquakes
What factors effect the risk of hazards?
- Unpredictability - many hazards aren’t predictable so people may get caught out by timing or the magnitude
- Lack of alternatives - people may stay in hazardous areas due to the lack of options e.g. for economic reasons
- Dynamic hazards - risk may increase or decrease over time
- Cost-benefit- benefits of living in hazardous areas may outweigh the costs e.g. fertile soil in volcanic areas for agriculture
- Fatalism - acceptance of a risk that will happen
What are the two classifications of hazards?
- Geophysical - hazards triggered by earth processes e.g. tectonic hazards or mass movement
- Hydrometeorological - hazards triggered by climate or weather processes e.g. tropical storms or floods
What is our case study for mega-disasters?
Haiti Earthquake in 2010
- 100% fall in GDP
- 200,000+ died
- International aid was needed
What are the different types of vulnerability?
- Physical vulnerability - when people live in hazard prone areas with buildings that offer little protection.
- Economic vulnerability - when people risk losing their jobs, assets and money
- Social vulnerability - when a community is unable to support disadvantaged people within it e.g. the elderly
- Knowledge vulnerability - when people lack education or training and have no or little warning systems
- Environmental vulnerability - where the area that people live in has increased in risk due to population pressures, forcing people into riskier areas
What is the distribution of volcanoes?
Around 500 volcanoes are active globally with 50 erupting on average every year.
The violence of these eruptions depends on the amount of dissolved gasses in the magma.
They are usually distributed along constructive and destructive plate boundaries. Many are found in the Pacific Ring of Fire.
Do volcanoes only occur at plate boundaries?
No there are intraplate volcanoes called hotspots e.g. Iceland or Hawaii
- They are when magma plumes break through the surface
- They can be on both type of plates
How was the Hawaiian islands formed?
They sit above the huge Pacific Plate mantle plume. The chain of islands was created as the lithospheric plate moved along the stationary mantle plume. Whichever point is over the mantle plume is active, e.g. the Big Island of Hawaii now
Can we predict volcanoes?
Yes with some degree of accuracy.
What are the signs of an imminent volcanic eruption?
- A series of small volcanoes due to the heat breaking surrounding rocks
- Changes to the volcanoes surface e.g. swells or budges due to increased pressure
- Changes to volcanoes tilt/dip due to pressure build up
- Historical eruption patterns e.g. whether a volcano erupts every 20 years
How are impacts of volcanoes predicted and what is this used for?
Risk mapping can be completed (e.g. predicating areas at risk of lahars) which could help produce land use zoning and strict planning laws.
E.g. Mouth Etna has areas where people cannot build due to risk
What is land reform?
It is used to help relocate people to less risky areas or encourage an increase in food production and stockpiling or diversify the economy so less jobs are lost due to disasters.
What are the three types of lava?
- Basaltic
- Andesitic
- Rhyolitic
What are the features of basaltic lava?
- It is the hottest lava
- Low silica, water and gases
- Formed by melting of mantle
- Low viscosity so gas can escape, allowing it to be gentle and effusive
- Located at hotspots, mid-oceanic ridges and shield volcanoes
What are the features of andesitic lava?
- Intermediate amounts of silica and gas
- High water contents
- Formed by subducted ocean plates melt and mixes with sea water
- Slow flow with intermediate viscosity that traps some gases so is violent and mildly explosive
- Located at composite cones and subduction zones
What are the features of rhyolitic lava?
- It is the coolest lava
- High in silica and gas
- Formed by the melting of lithospheric mantle
- High viscosity so traps most gas leading to very violent and cataclysmic eruptions
- Located at super volcanoes and composite cones
What are the two types of volcano?
- Composite cone/stratovolcano
- Shield volcano
What are features of composite cone volcanoes and give an example.
- Formed by alternating layers of viscous lava and ash deposits
- Tall with a narrow base
- Associated with destructive boundaries
- E.g. Mount St Helens, USA
Has hazards like:
- Ash clouds
- Tephra
- Pyroclastic flows
- Lava flows
What are features of shield volcanoes and give an example.
- Formed by runny basaltic lava that flows a great distance before cooling
- Shallow with wide base
- Associated with constructive boundaries
- E.g. Kilauea, Hawaii
What are the primary hazards of volcanoes?
Include case studies
- Lava - This is magma that has reached the Earths surface. Its extremely hot. Fast flows can pose significant threats but most move slowly. They destroy everything in their path.
E.g. Nyiragongo, DRC where a lava lake drained rapidly and killed 400 sleeping people - Tephra - This is pieces of volcanic rock and ash which are blasted into the air in an eruption. Range from large ‘bombs’, which can destroy houses, to ash which can be distributed globally.
E.g. Eyjafjallajökull, Iceland where the ash cloud stopped European flights for a week (100,000 + flights cancelled). Over 700+ people were evacuated to avoid breathing in ash. Main roads closed due to visibility. - Pyroclastic flows - This is a dense mixture of extremely hot tephra and poisonous gases that move rapidly, from composite cone volcanoes, up to 700kph.
E.g. Soufriere Hills, Montserrat where 11,000 people where evacuated to the North of the island to escape pyroclastic flows. - Volcanic gases - the most common is water vapour which can lead to heavy rainfall or sulphur dioxide which can get taken high into the stratosphere and reflect the suns radiation.
E.g. Mt Pinatubo, Philippines which produced 20m tonne sulphur dioxide cloud which cooled the earth for 3 years by 0.6C
What are the secondary hazards of volcanoes?
Include case studies
- Lahars - This is volcanic mudflows that consist of water mixed with volcanic deposits that flow rapidly along valleys. They are caused by heavy rainfall, the emptying of a crater lake or snow/ice melt. The degree of hazard depends on the steepness of slope and volume.
E.g. Soufriere Hills, Montserrat where lahars destroyed large area of the island including homes and the only hospital and airport.
*Jökulhlaups - This is glacial outburst floods, which is a large very sudden flood with a rapid discharge of large volumes of water, ice and debris from a glacial source.
Occurs when a volcano erupts underneath the ice and melts it to form a lake, eventually this meltwater will have enough volume to lift the ice away from the ground and carry it away. This will wash away anything in its path and change river channels.
E.g. Eyjafjallajökull, Iceland where the main road along the south coast is often cut off and bridges washed away, due to this regularity, jökulhlaups caused by E-16 were anticipated and roads were closed + embankments set up
Which country is our case study for multiple hazard zones and volcanic activity in emerging countries?
Philippines
Why is the Philippines at risk from natural hazards?
- Is on a destructive plate boundary (Philippines plate is subducted under Eurasian plate) so has both seismic and volcanic activity.
- N and E coastlines face Pacific Ocean so prone to tsunamis
- Lies in a major typhoon melt with a tropical monsoon climate causing risks of landslides and flooding
- 18 active volcanoes out of 37, with 30% of the population living close to a volcano
- Steep topography, high levels of rain and deforestation increases risk of landslides
Why is the Philippines so vulnerable?
- Rapidly developing middle income country with fast growing population
- Rapid urbanisation and high population density
- Most deprived people live coastally so at risk of storm surges and flooding etc. made worse by poor infrastructure
- 25% of population in poverty
How does being an MHZ challenge the Philippines?
- One hazard can have knock on effects and cause other hazards
- Events happening in short time from each other while communities try and recover from last one another one happens, drains resources + services
Which volcano eruption event is the case study for the Philippines?
Mt Pinatubo, 1991
What were the primary impacts of the Mt Pinatubo eruption?
- 400 dead
- Global dimming due to large ash cloud that spread globally, global temp dropped 0.6C in 3 years
- 200,000+ homeless
- $710 million in damages
What were the secondary impacts of the Mt Pinatubo eruption?
- Measles spread with 400+ people dying from it
- 550,000+ people jobless
- Lahars contaminated water
- Loss in indigenous communities due to disease in the emergency camps (400 dead)
What was the immediate response after the Mt Pinatubo eruption?
- 58000 evacuated due to early warning systems
- Evacuation camps were built
- US geological service helped with predication
- Exclusion zone was set up before due to prediction
What was the long-term response after the Mt Pinatubo eruption?
- New houses were built on stilts
- International aid was provided
- Equivalent of $60,000 raised (in pesos)
- Dykes were built (but were washed away)
What is our case study for volcanic activity in developed countries?
Eyjafjallajökull, Iceland 2010
What were the primary impacts of the Eyjafjallajökull eruption?
- Ash cloud blocked the sun and chocked people
- Homes and roads damaged
- Flights cancelled (100,000)
What were the secondary impacts of the Eyjafjallajökull eruption?
- Food import delays
- Water supplies contaminated
- Glacier melt caused floods/jökulhlaups
What was the immediate response after the Eyjafjallajökull eruption?
- Evacuated 700 people
- Foreign aid provided by the Red Cross
What was the long-term response after the Eyjafjallajökull eruption?
- Improvements to European air traffic management
What is our case study for volcanic activity in developing countries?
Soufriere Hills, Montserrat 1995
What were the primary impacts of the Soufriere Hills eruption?
- 19 people killed
- Many buildings including the hospital was destroyed
What were the secondary impacts of the Soufriere Hills eruption?
- Lahars destroyed large areas
- The capital was covered in mud and ash from pyroclastic flows
- Top heavy population pyramid as young people left for better opportunities
What was the immediate response after the Soufriere Hills eruption?
- Evacuations
- Donations from British Government
What was the long-term response after the Soufriere Hills eruption?
- Exclusion zone set up
- Volcanic observatory built
- New roads + airport built
What is the distribution of earthquakes?
Hundreds of earthquakes occur globally every day, but most are not felt.
95% of earthquakes occur at plate boundaries. Many occur at the Pacific Ring of Fire.
What are the causes of earthquakes?
- Plate movements cause pressure to build up in the Earths crust
- As the strength of the rock is exceeded, it fractures along cracks called faults
- This causes energy to be quickly released as seismic waves
- This is known as elastic rebound
What are the 4 types of seismic wave?
- Primary
- Secondary
- Love
- Rayleigh
What is a primary wave?
- It is the fastest of the body waves
- It arrives at surface first
- Moves through solid rock and fluids
- Compressional/ push and pull movement
What is a secondary wave?
- Travels slower than P-wave
- Arrives at surface second
- Only moves through solids
- Up and down movement
What is a love wave?
- Longest wavelength
- Fastest surface wave
- Arrives at surface third
- Travels only through crust
- Moves side to side while going forwards
What is a Rayleigh wave?
- Slowest wave
- Arrives at surface last
- Travels only through crust
- Rolling motion
- Responsible for the shaking felt
How does seismic activity vary at different plate boundaries?
At constructive margins, earthquakes are shallow and low magnitude.
At destructive margins, earthquakes have a range of focal depth and are moderate to high magnitude
At collision margins, earthquakes have a shallow to moderate focus and moderate magnitude
At conservative margins, earthquakes are shallow and moderate magnitude
Do earthquakes only occur at plate boundaries?
No, they can also occur at hotspots, ancient fault lines or after isostatic readjustment/
They may also occur due to human activity e.g. fracking or mining
How are earthquakes magnitude measured?
Moment Magnitude Scale (MMS) - measures the total energy released by the earthquake at the moment it occurs, taking into account:
- size of the seismic waves
- amount of slippage or rock movement
- area of the fault surface broken by the earthquakes
- the resistance of the affected rocks
It works in an infinite scale starting from 1, but usually stops at 10 (as largest recorded is 9.5). It is also logarithmic so magnitude 5 is 10x more powerful than 4.
How are seismic waves recorded?
Using a seismometer
What factors affect the impact of earthquakes?
- Physical factors:
- Magnitude
- Depth of focus
- Distance from epicentre
- Sub-surface geology
- Relief
- Coastal location (for tsunamis)
- Secondary factors:
- Level of development
- Population density
- Level of preparedness
- Effectiveness of emergency response
- Impact of indirect hazards
How are earthquakes intensity measured?
Modified Mercalli Intensity Scale (aka Mercalli Scale) -
This is a subjective measure that takes observations from people who experienced the earthquake and puts them on a scale. This scale goes from 1 (hardly noticed) to 12 (catastrophic) written in roman numerals.
What are the primary hazards of earthquakes?
- Ground shaking - damages buildings and other infrastructure or causes them to collapse, killing or injuring people.
- Crustal fracturing - when energy released during an earthquake ruptures the Earths crust
What are the secondary hazards of earthquakes?
- Liquefaction - violent shaking causes surface rocks to looks strength. Water rises towards the surface, causing the ground to behave like a liquid. This makes it unable to support buildings and makes rescue efforts more difficult
- Mass movement (e.g. landslides and avalanches)
- Tsunamis
- Aftershocks
Can scientists predict earthquakes?
Not yet but we are able to know which areas are most at risk especially if time since last earthquake, which is known as seismic gap theory, is considered.
Forecasting allows us to say where an earthquake may happen but not when.
Researchers can also look at warning signs that may suggest earthquakes are coming.
What is our case study for seismic activity in developed countries?
Tohoku earthquake, Japan 2011
What were the primary impacts of Tohoku earthquake?
- 16,000 people killed
- 450,000 made homeless
- Fukushima disaster
What were the secondary impacts of Tohoku earthquake?
What was the immediate response after the Tohoku earthquake?
- 100,000+ defence troops were mobilised
- All radio and TV were immediately switched to official earthquake coverage
- International aid recieved
What was the long-term response after the Tohoku earthquake?
- Bank of Japan offered over $180 billion to banks so they could keep operating and protected Japan’s economy
What is our case study for seismic activity in emerging countries?
Sichuan, China 2008
What were the primary impacts of Sichuan earthquake?
- 5 million homeless
- Poorly built buildings (due to political negligence) collapsed, many being schools
- 5,000+ kids died due to schools collapsing
What were the secondary impacts of Sichuan earthquake?
- Landslides led to more deaths
What was the immediate response after the Sichuan earthquake?
- 130,000 soldiers and relief workers were sent out
- Medical centres quickly restored
- Temporary homes and roads set up
What was the long-term response after the Sichuan earthquake?
- $10 billion pledged by government to rebuild
- 40,000+ people were moved into the new city of Yongchang but there were problems with officials being bribed
What is our case study for seismic activity in developing countries?
Port-au-Prince, Haiti 2010
What were the primary impacts of Haiti earthquake?
- 1/4 of government officials were killed
- Roads and airport was damaged which made aid efforts harder
What were the secondary impacts of Haiti earthquake?
- Liquefaction led building foundations to sink
- Outbreak of cholera (720,000 effected by 2015)
What was the immediate response after the Haiti earthquake?
- Temporary camps set up
What was the long-term response after the Haiti earthquake?
- $13 billion in aid donated
- Some improvements in infrastructure
Why was the death toll lowest in Japan out of the three earthquake case studies?
It is a highly developed country with a high capacity to cope:
* Has good building constructions and strict regulations
* Low levels of corruption
* Well designed disaster plans
* Early warning sign
* Regular emergency drills preformed
Which earthquake case study has a low capacity to cope and why?
Haiti:
- Poverty and lack of wealth meant limited resources were spent om other things and not earthquake preparedness
- High levels of local and national corruption
- Lack of building controls and regulations so many buildings were slim dwellings which easily collapsed
- Dense urban areas
- Lack of disaster preparation
What causes tsunamis?
- Most are caused by large underwater earthquakes at subduction zones
- Energy released during the earthquakes uplifts the sea floor, displacing the water column above.
- When waves reach the shoreline, they produce a vacuum effect, sucking water back out to sea and exposing the sea floor.
- The tsunami breaks on the shore as a series of large waves.
What is the distribution of tsunamis?
They tend to occur along plate boundaries as they are usually linked to tectonic events.
Many are found in the Pacific ‘Ring of Fire’
What are the impacts of tsunamis?
- Large tsunamis travel inland for several miles.
- Soil is washed away, undermining building foundations and destroying agricultural land.
- Landscapes can be completely changed with small islands being completely destroyed.
- Most deaths are from drowning, but many are also killed/injured by collapsing buildings or falling debris
- Inland flooding many contaminate food and water supplies leading to disease outbreaks
How are tsunamis predicted?
Tsunamis are hard to predict just as earthquakes are, but early warnings are possible. These systems are both in place in the Pacific and Indian Oceans.
Seismic sensors are used to detect underwater earthquakes.
A system called DART (Deep-ocean Assessment and Reporting of Tsunamis) is used to see if a tsunami has been caused by an earthquake.
Seabed sensors and surface buoys monitor changes in sea level and pressure, and satellites relay information to warning stations.This can allow for people to have a few hours of warning.
What is our case study for tsunamis in developed countries?
Tohoku, Japan 2011
What were the impacts and responses to the Tohoku tsunami?
What is our case study for tsunamis in developing countries?
Indian Ocean Tsunami 2011
What were the impacts and responses to the Indian Ocean tsunami?
What is our case study for tsunamis in emerging countries?
Philippines multiple hazard zone
What were the impacts and responses to the Philippines tsunami?
How did the Filipino government try to increase resilience and reduce risk?
They passed the Disaster Risk Management Act in 2009. This included:
* Removing illegal settlers from areas prone to hydrometeorological hazards
* Having an advisory system for metrological and volcanic events
* Mapping of fault systems
* A detailed National Disaster Risk Reduction and Management plan for 2011-2028
* A National Disaster Response pillar that provides information and links all governments and agencies for coordination
What makes the Philippines a MHZ?
- There are over 7000 islands where many people live coastally for fishing.
- Large, dense population
- It’s located on the Pacific Ring of Fire and a subduction zone of the Philippine and Sunda plates
- It has 37 volcanoes
- It experiences many earthquakes
- Its located on the typhoon belt and is affected by monsoon rains so storms are common
- 74% of population live at risk of 2 or more hazards
How was the Mt Pinatubo 1991 eruption predicted?
It was successfully predicted by the United States Geological Survey (USGS) working with a local high quality research centre, PHIVOLCS.
The prediction involved measuring sulphur dioxide emissions and seismic networks
What hazards were present during the Mt Pinatubo eruption?
- Volcanic eruption
- Ash
- Monsoon rain
- Typhoons
- Pyroclastic flows
- Lahars
What were the social impacts of Typhoon Haiyan?
- 7000+ people killed
- 1.9 million homeless
- Disease spread due to lack of resources
- Influx of internal migration to less effected areas
What were the economic impacts of Typhoon Haiyan?
- $13 billion+ total economic loss
- 70,000+ acres of farmland affected
What are the two major theoretical models used for hazard management?
The Parks Model and the Hazard Management Cycle
What is the Parks Model?
A model that shows how a country might respond after a hazard event. It can be used to directly compare how areas at different levels of development might recover from a hazard event.
What are the 4 groups of time in the Parks Model?
- Pre-disaster
- Relief (hours -> days after disaster)
- Rehabilitation (days -> weeks after disaster)
- Reconstruction (weeks -> years after disaster)
What does the Parks Model show and how is it used?
It shows the impacts of a hazard event change over time and depends on factors such as its size, development level of affected areas and the amount of aid received.
Economically developed countries will have a very different curve to developing countries as they have the ability to recover faster
What is the hazard management cycle?
What are the 4 stages of the Hazard Management Cycle?
- Mitigation/prevention
- Preparedness
- Response
- recovery
What is the focus of the mitigation stage, how is this achieved and when does it take place?
Focus:
- Identify potential hazards and reduce their impacts
- Reduce loss of life and property
Actions:
- Land use planning
- Developing building regulations
- Building protective structures
Takes place before a hazard event
What is the focus of the preparedness stage, how is this achieved and when does it take place?
Focus:
- Minimising loss of life and property
- Emergency planners develop plans for both governments and aid governments
Actions:
- Making preparedness plans
- Early warning systems
- Evacuation routes
- Stockpiling aid supplies
-Raising public awareness
Takes place before a hazard event
What is the focus of the response stage, how is this achieved and when does it take place?
Focus:
- Coping with disaster
- Save lives
- Protect property
- Make affected areas safer
- Reduce economic losses
Actions:
- Search and rescue
- Evacuation
- Restoring critical infrastructure such as water and power
During and immediately after hazard event
What is the focus of the recovery stage, how is this achieved and when does it take place?
Focus:
- Dealing with immediate needs (short term)
- Taking steps to reduce future vulnerability (long term)
Actions:
- Health and safety services
- Restoring permanent infrastructure like water and power
- Re-establishing transportation
- Financial assistance
- Rebuilding homes
- Reopening businesses and schools
Takes place after hazard event
Define mitigation
Strategies to avoid, delay or prevent hazard events
Define adaptation
Strategies to reduce the impacts of a hazard event
What is land use zoning?
Provide examples
It is when local governments regulate how land may be used. In hazard prone areas, it is an effective way of protecting people and property. Hazard maps are used in decision making for things like evacuation routes. Building may be limited in these areas with some types being prohibited e.g. nuclear power stations
An example is Monseratt.
What is diverting lava flows?
Provide examples
Historical method to divert lava flows away from settlements through building barriers or digging channels. However, they are usually ineffective as it’s hard to determine which directions lava will flow.
An example is Iceland where they sprayed seawater to cool and solidify lava flows that threaten settlements or people.
What is GIS mapping?
Provide examples
Geographical Information Mapping systems use satellites and computer technology for maps at all stage sog the disaster management cycle. They can be used to identify evacuation routes or help with rescue and recovery.
An example is the Nepal 2015 earthquake
What is aseismic design and engineering defences?
Provide examples
Effectively designed buildings that can withstand hazard events are key to reducing impacts. This is when buildings are designed to resist ground shaking during earthquakes.
In volcanic areas, roofs can be sloped to reduce build-up of ash and stop them collapsing.
An example is the Sky Tree in Japan, which is the tallest tower in Japan but is still able to withstand the common tectonic activity
How do countries modify vulnerability/resilience?
- High tech monitoring
- Crisis mapping
- Impact modelling
- Public education and preparedness
What is high tech monitoring?
Provide examples
It is where GIS helps to create hazard maps and manage hazards more effectively.
Early warning systems use instruments to detect signs of a hazard and send out rapid alerts to at risk communities
Satellite communication helps transmit data for early warnings
Mobile phone technology is used to communicate warnings and coordinate preparation activities
E.g. Indian Ocean Tsunami 2004
What is crisis mapping?
Provide examples
It uses crowdsources information (information from volunteers etc) to accurately map and area, which can help aid agencies, who use it before hazards to identify at-risk areas
E.g. Haiti Earthquake 2010 where an online map was set up for Haiti where people could submit data to update volunteers of areas where help was needed
What is impact modelling?
Provide examples
Using computer models of hazards to allow scientists to predict impacts on communities
What is public education and preparedness?
Provide examples
Education and public awareness reduce vulnerability and prevents hazards becoming disasters. Plans are set up by local communities and local residents are educated. Activities include creating lists of vulnerable people, providing first aid courses and organising practice evacuation drills
E.g. Japan has an annual Disaster Prevention Day on 1st September and earthquake drills are held 4 times a year
How do countries modify loss?
- Aid
- NGOs
- Insurance
- Community led recovery
What is aid and how does it help modify loss?
Provide examples
There is emergency aid (food, water, shelter), short-term aid (temporary restoration of water supplies and temporary shelters) and long-term aid (rebuilding infrastructure and redeveloping the economy)
E.g. Aid was sent after the Haiti Earthquake 2010 which was controlled by aid agencies
What are NGOs and how do they help modify loss?
Provide examples
Non-governmental organisations
They are important where local response is limited and ineffective due to lacking resources. They tend to be involved in all stages of the Hazard Managment Cycle and remain for several years after a hazard to help rebuild.
E.g. Red Cross aid was provided after Eyjafjallajökull eruption 2010
What is insurance and how does it help modify loss?
Provide examples
Natural disasters are expensive with global losses being $54 million in 2011.
Insurance cover helps communities to recover by providing money for repairs and rebuilding.
What is community led recovery and how does it help modify loss?
Provide examples
Where local people are first to respond and play a crucial role in the community’s recovery. This includes search and rescue, clearing of debris on roads for aid access and first aid.
Long term strategies are reliant of community involvement.
E.g. Communities in Japan make plans for when hazards occur
What are the overall disaster trends since 1960?
- Total number of recorded hazards has increased
- The number of reported disasters is decreasing
- The number of deaths is lower than in the past
- The number of people affected is increasing
- The economic costs have increased significantly
How reliable are disaster statistics?
- No as there is no universal definition of a disaster
- It depends on whether primary deaths alone are counted or whether secondary deaths are considered
- Location effects it as remote places are under-reported
- Political factors/bias effects it. E.g. Impacts of the 2004 Asian tsunami were played down by Thailand to protect its tourism industry
- Rural areas may have difficulty collecting disaster statistics
