Hazards full Flashcards
what is a hazard?
it is a potential threat to human life and property. it can either be hydro-meteorological or geophysical
what are hydro-meteorological hazards?
caused by climatic processes
what are geophysical hazards?
caused by land processes
where do geophysical hazards occur?
they occur near plate boundaries. these plates moved different speeds and directions which can cause collisions, earthquakes and volcanic activity.
where do earthquakes mainly take place?
greatest in the Pacific Ocean along the ring of fire. also the entire ocean is ringed by areas known as subduction zones.
other than near plate boundaries where else can earthquakes occur?
near the middle of plates (called an intra-plate). this is when pre-existing weaknesses become reactivated, forming seismic waves. for example, an intraplate earthquake may occur if solid crust, which has weakened over time, cracks under pressure
explain volcanic hotspots
- these occur ‘intra-plate’ meaning amongst the centre of plates
- this occurs when a localised area of the lithosphere (earth’s crust and upper mantle) has an unusually high temp due to the upwelling of hot molten material from the core. this was first theorised by Tuzo Wilson in 1963.
- This produces isolated plumes of convecting heat, called mantle plumes, which rise towards the surface, generating basaltic volcanoes that tend to erupt continuously.
- This over time can produce a chain of volcanic islands.
e.g. Kilauea, Hawaii
where do the most powerful earthquakes generally happen?
at convergent or conservative boundaries
what is the OFZ (oceanic fracture zone)?
this is a belt of activity through the oceans and along the mid-ocean ridges through Africa, the Red Sea and the Dead Sea
what is the CFZ (continental fracture zone)?
this is a belt of activity along the mountain ranges from Spain through the alps to the Middle East and to the Himalayas
what are the tectonic trends since 1960?
- the total number of recorded hazards, one of the main reasons for this is due to CC and global warming.
- the number of fatalities has decreased due to the increased protection and preparation
- the total number of people being affected by tectonic hazards is increasing, due to pop growth, increased density has increased vulnerability
- the economic costs associated with hazards and disasters has increased significantly. this is partly due to increases in development as infrastructure in more developed countries costs more to repair. increasing number of insurance policies, especially in developed countries, heightens the costs.
why is reporting disaster impacts (e.g. fatalities) very difficult and controversial?
- depends on whether you look at the direct deaths so those killed straight away or indirectly by looking at how many people died of diseases that spread after the disaster
- the location is important as rural and isolated areas are hard to reach and so it may be hard to collect data from them.
also areas of high pop densities may be hard to collect from - the number of deaths quoted by a government may be subject to bias. in the 2004 tsunami, the Burmese government claimed there were 0 deaths in Burma. this may be to try and show the government is doing a good job.
what are the four sections of the earth?
crust
mantle
outer core
inner core
what is the crust like?
also known as the lithosphere. the uppermost layer of the earth which is thinnest, least dense and lightest. oceanic crust is only 7km thick, whereas continental crust can be up to 70km thick
what is the mantle like?
may also be called the asthenosphere. widest layer. the mantle is semi-molten and a temperature gradient towards the core generates convection currents. this may contribute to the lithosphere’s plate tectonic movement. the mantle is at a depth from 700km to 2890km below the crust.
what is the outer core like?
dense, semi-molten rocks containing iron and nickel alloys. at a depth of 2890km to 5150km below the earth’s surface. temps of 4500-6000ºC
what is the inner core like?
similar composition to the outer core. its over 5150km below the earth’s crust. the inner core is solid iron due to the extreme pressures it experiences. temperature of over 5000ºC. the core’s high temperature is a result of:
- radiogenic heat produced form radioactive decay
- primordial heat left over from the earth’s formation
what is the lithosphere?
consists of the crust and the rigid upper section of the mantle and is approximately 80-90km thick. this is the section of the earth that is divided into seven very large plates and a number of smaller ones. the plates are divided into oceanic and continental plates.
what is the asthenosphere?
this lies beneath the lithosphere and is semi-molten on which the plates float and move
what causes tectonic plates to move?
radioactive reactions occur inside the core which produces convection currents in the mantle. this causes the tectonic plates to move. The friction between the convection current and the crust causes the tectonic plate to move.
where are volcanoes predominately located?
along the ring of fire which borders the indo-australian plate to the south west, the Eurasian plate to the north west and the North American plate to the west
- they are usually found at plate boundaries where plates converge or diverge, anomalies include hotspots.
what was wegner’s continental drift theory?
- in 1912 he published his theory that a single continent that he called Pangea, existed about 300 million years ago
- he states that the shapes of South America and Africa seem to fit together so were once part of a supercontinent
- he suggested mountains formed when the edge of a drifting continent collided with another causing the floor to crumble and fold
- took 150 years to be accepted as scientists still believed mountains are causing by cooling of the earth as well as it being difficult to find viable evidence
what are examples of Wegner’s continental drift theory?
- similar fossils found where these plates could have fit, but are now separated by oceans. remains of the reptile Mesosaurus found in both South America and southern africa. it is unlikely that the reptile could have developed over both areas or migrated across the Atlantic
- rock sequences in northern Scotland closely agree with those found in eastern Canada, indicating that they were laid down under the same conditions in one location
- land masses fit like a jigsaw
other than Wegner what is another piece of evidence for continental drift theory?
how seismic waves travel through the earth. along the wadati-benioff foci, the depth of waves shows subdiction of the denser basaltic oceanic plates into the upper mantle.
what are divergent plate boundaries?
- when plates move apart causing magma to rise through the cracks to form new land
- they form mid-ocean ridges (e.g. mid-atlantic ridge)
- sub-marine volcanoes form as magma rises, less explosive
- ridge push (the bubbling magma causes plates to move apart)
- creates great Rift Valley (continents) where crust is stretched and land between faults collapses
e.g. mid-atlantic ridge
what are convergent (oceanic - continental) plate boundaries?
- subduction occurs at the Benioff zones and an earthquake occurs from the friction of the two plates
- the oceanic plate is denser than the continental plate which causes the mantle to melt through wet partial melting
- this causes an explosive eruption of andesitic lava with high gas and silica content, volcanic plug
- fold mountains occur when the continental crust is pushed up
- tsunamis due to mega thrust, water column displacement
An example of a destructive plate boundary is where the Nazca plate is forced under the South American Plate
what is a locked fault?
when two interlocked rocks create pressure to then grind and create pressure and tension
what is a convergent (oceanic - oceanic) plate boundary?
- very similar to continental to oceanic but the oceanic plate that is denser is subducted leaving an ocean trench.
- through the friction in the Benioff zone it causes the melting of the mantle causing submarine volcanoes
- this creates island arcs and eventually an atoll, this is when lava cools above sea level and creates new land
an example of an island arc is the Japanese islands
- fold mountains will also occur
- tsunamis (low-lying coastlines)
what is a convergent (cont-cont) plate boundary? (collision boundary)
- aka collision margin
- because they have the same density less subduction occurs but instead a lot of pressure builds up which can result in a very powerful earthquake
- fold mountains (Everest) formed on top of lithosphere due to pressure from continental crust as sediment crumbled and is formed upwards
- ancient oceanic crust is subducted slightly, but there is no subduction of continental crust
- but if some layers are more compressed then some subduction occurs and focus is shallow
e.g. The Indian plate and Eurasian plate colliding to form the Himalayan mountain range
what is a conservative/transform plate boundary?
- aka transform boundary
- two plates moving parallel against each other in different directions or at different speeds, creating friction resulting in a high magnitude earthquake from its shallow focus
- rocks grinding past each other (San Andreas fault line) causes a locked fault which causes a transform fault (crustal fracturing), tension creates cracks which causes further earthquakes
- this can form deep trenches and ridges
e.g. san Andreas fault lin
what is paleomagnetism?
- It results from magma locking in the earth’s magnetic polarity when it cools. Scientists can use this to reconstruct past plate movements.
- The discovery in the 1960s by Hess of magnetic strips in the oceanic crust of the seabed which are palaemagnetic signals from past reversals of the earth’s magnetic field.
- It proves that new ocean crust is created by the process of sea-floor speading at mid-ocean ridges.
- He discovered using sonar that the seafloor isn’t flat, there were mountain ranges in the middle of it.
- This led to the discovery that the ocean floor is getting progressively older the closer to the coast and that newer coast must be produced by molten rock inside.
- He also found that the pushing at the ridge and the pulling at the convergent margin resulted in sea floor spreading
what are intraplate earthquakes?
- middle of the interior a plate, old fault lines can react
- earthquakes occur in mid-plate settings, are usually associated with major ancient fault lines being retracted by tectonic stresses
or when collision of plates can fracture crust in the interior - happens in the earth’s interior
- perhaps old collision theories, already has cracks and faults
what are intraplate hotspot volcanoes?
- volcanoes at a distance from the boundary
- isolated plumes of convecting heat (mantle plumes) rise towards the surface generating basalt volcanoes that erupt continuously, the plume is stationary but the plate moves slowly above it
- produces a chain of volcanic islands = atoll
- e.g. Kilauea, Hawaii
- causes shield volcanoes, low viscosity and effusive lava
- mantle plume goes through the cracks and melts the crust
what are the different mechanisms that could cause plate movement?
1) mantle convection- radioactive elements in the core of the earth decay which produce a lot of thermal energy. this causes the lower mantle to heat up and rise, as the magma rises it cools down becomes more dense and begins to sink back down to the core. these are CONVECTION CURRENTS. they push the plates
2) slap pull- This is where older and denser oceanic crust will subduct beneath less dense continental plate. The density of the oceanic plate pulls itself into the mantle. The pulling action drags the rest of the plate with it (first theorised by Dan McKenzie)
how have thoughts on the primary cause of late movement changed?
previously, convection currents were thought to be the primary cause of plat movement. however, researches now believe that slab pull is the primary mechanism for plate movement. connection currents seem to weak to move massively dense plates.
explain the forming of earthquakes
A locked fault on a plate which creates tectonic strain as they can’t grind past each other easily. This leads to a build up of pressure which eventually exceeds the strength of the plates leading to elastic rebound, which eventually causes the pressure to be released in the form of seismic waves which radiate from the hypocentre in the form of an earthquake. this can lead to crustal fracturing and the ground to shake.
what is the epicentre?
the area above ground that is directly above the hypo centre (shaking tends to be worse here)
what is the hypo centre?
the point at which tension and friction releases seismic waves
where do the most powerful earthquakes occur?
at destructive and conservative boundaries
how does an earthquake happen at a constructive boundary?
Plates move at different speeds, which builds pressure until plates crack, causing fault lines. This results in the release of energy in the form of seismic waves, producing earthquakes.
how does an earthquake happen at a destructive boundary?
one plate is forced under the other, getting stuck due to friction which produces energy. As plates suddenly jerk past one another, this energy is quickly released as large seismic waves, forming a powerful earthquake.
how does an earthquake happen at conservative boundaries?
plates lock with one another which, when pressure is built, produces sudden seismic waves.
explain the theory of plate tectonics
convection currents happen due to radioactive elements in the core of the earth decay (into uranium) which produce a lot of thermal energy. this causes the lower mantle to heat up and rise, as the magma rises it cools down becomes more dense and begins to sink back down to the core.
- sea floor spreading occurs (youngest at ridge and oldest at subduction zone)
- proved by palaeomagnetism (orientation of magnetic minerals to earth’s magnetic force)
- ridge push: magma pushes u[ as crust splits and pushes crust outwards
- slab pull: heavy weight of the crust pulls it downwards towards subduction zone at edge of ocean
what are the 4 types of seismic waves?
primary
secondary
Rayleigh
love
what are primary waves?
- they are caused by compression pushing and pulling in the direction of travel
- travels fastest at 4-8 km/s and arrive first
- side to side movement (crust, mantle and core)
what are secondary waves?
- Vibrate at right angles to direction of travel
- Travels only through solid rocks (up and down movements)
- Travels slower at 2.5-4 km/hr, 60% slower than P waves
- Shaking (crust and mantle only)
what are love waves?
- Only travels through surface of the crust
- Fastest surface waves with high amplitude
- Move from side to side
- Causes most damage due to longer wave length and focus of energy at the surface
- Travels at 2-6 km/hr
what are the strongest types of seismic waves?
Secondary and Love waves are the most destructive as they have large amplitudes.
Due to their different speeds, these different waves will hit a location at different speeds. The aftershocks the survivors feel are these different types of waves arriving after each other.
These waves can also result in crustal fracturing (producing faults), ground shaking and secondary hazards such as landslides, avalanches and liquefaction.
when will the intensity of seismic waves decrease?
they will decrease further from the epicentre as waves lose energy as they travel. However, this does not mean that impacts felt or damage caused will always decrease further from the epicentre as other factors affect a location’s vulnerability
what are the factors affecting vulnerability for an area?
- Geology
- Geographical location (whether the earthquake occurs nears the sea or intraplate)
- Education of locals
- Durability of buildings
- Mitigation
how are earthquakes measured?
moment magnitude scale
modified mercalli scale
what are the factors explaining the intensity of an earthquake?
- Seismic intensity = what you feel
- Proximity to the epicentre
- Types of soil / rock and distance from the epicentre
- Magnitude= the size of the earthquake and the energy intensity released
- Depth of focus
- Shallow hypocentre means higher intensity
- Soil substrate, if it is wet, soft or sandy then intensity will rise, liquefaction, soft saturated bay mud is x5 more damaging than bay rock
what is the mercalli scale?
- intensity reflected by effects/damage
- lower numbers correspond to little damage
- Very subjective scale based on where you are, closer to the epicentre there is more shaking
- Usually, the stronger the magnitude the greater the intensity but local factors can modify this, e.g. being closer to the epicentre, type of geology can amplify shaking
what is peak acceleration?
how quickly the ground shook, how swiftly it changed direction
what is a secondary hazard?
a hazard that is a result of a primary hazard, e.g. landslides, flooding, sinkholes, tsunamis
what is a primary hazard?
caused by the initial process, e.g, the earthquake, ground shaking, crustal fracturing
what are the secondary hazards of earthquakes?
soil liquefaction
landslides
slope processes/mass movement
tsunamis
explain the secondary hazard of earthquakes: soil liquefaction
Earthquake shaking causes the water pressure to decrease and the soil to lose mechanical strength and so the structure is lost and the soil acts as a liquid and bubbles up to the surface, which can cause building subsidence or landslides.
- Affects poorly compacted sand and silt
- Water moisture within the soil separates from the soil particles and rises to the surface
- The upwelling of liquid means that the soil underneath the buildings becomes muddy and the sink collapses. If it’s on a hill, the liquid soil can cause mud/landslides
explain the secondary hazard of earthquakes: landslides
- The shaking caused by the earthquake can weaken or damage cliff faces, hills and snow material
- Soil is loosened by rain or gravity, ground eroded by heavy rain causes rock to fall
- Unconsolidated material or loose rocks can collapse
- Landslides can travel several miles and accumulate material on the way
- Risk varies with topography, rainfall, soil and land use
explain the secondary hazard of earthquakes: tsunamis
- Tsunamis have a long wavelength (150-1000 km) and a low height in comparison (5m) until they reach the shallow bed and grow. The shallow sea bed slows down the lower proportion of the wave till the upper particles catch up causing it to grow taller.
- Tsunamis present additional damage to vulnerable communities such as accelerating coastal erosion, which is a case in Malibu in California
- They are generally generated in subduction zones at convergent plate margins. Most tsunamis are found along the ring of fire, hence the most vulnerable countries are often located in Asia or Oceania. 90% occur within the Pacific basin (biggest and deepest)
what is the formation of tsunamis?
1) Tsunamis are produced by sub-marine earthquakes at subduction zones causing tectonic strain and elastic energy to be build up in the Benioff zone causing water displacement and deep trough waves
2) When an oceanic crust is jolted during an earthquake, all of the water above this plate is displaced, normally upwards forming tall waves with a high crest
3) This water is then pulled back down due to gravity. The energy is transferred into the water and travels through it like a wave.
4) The water travels fast along the ocean water column but with a low amplitude (height).
5) As it gets closer to the coast, the sea level decreases so there is friction between the sea-bed and the waves, causing the wave to slow down.
6) This creates a wall of water that is on average 10 feet high but can reach 100 feet. This will eventually crash onto the shore and once the energy is lost, the water drags debris back into the ocean.
what are the primary hazards of earthquakes?
- ground shaking
- crustal fracturing
what is moment magnitude (magnitude) for earthquakes?
- the moment magnitude scale measures from the energy released by an earthquake, usually in terms of the amount of fault slip
- better for higher magnitudes
- Based on energy released (compared to TNT/Kg) from all shock waves and the area of rupture and plate movement
- More accurate than the original Richter scale as that only measure P and S waves measured on a seismograph
- Both MMS and Richter are logarithmic
what is modified mercalli scale (intensity) for earthquakes?
- looks at relative affects due to shaking
shaking depends on: - magnitude
- distance from epicentre
- depth of focus
- rock type (amplification)
- Measures intensity using the amount of damage caused by shaking
- Very subjective scale based on where you are, closer to the epicentre there is more shaking
- Geology can affect shaking, e.g. In Haiti, unconsolidated sediment shook violently, saturated foundations in Christchurch caused liquefaction
- Usually, the stronger the magnitude the greater the intensity but local factors can modify this, e.g. being closer to the epicentre, type of geology can amplify shaking
what human factors influence the impact of a tsunami?
- Quality of Warning and Evacuation Systems
- Population density of area hit, if the population is higher then more people are likely to be affected, tourism, industry
- Coastal defences (e.g. sea walls)
- Level of economic and human development
what physical factors influence the impact of a tsunami?
- Wave amplitude, amount of water displaced, velocity and distance travelled
- Degree of coastal ecosystem buffer (e.g. mangrove trees, barrier island, coral reef)
- Timing at which the tsunami hits (day or night)
- The topography of the land, water depth, bays will funnel and concentrate tsunami waves
what are the high risk zones for a tsunami?
- Coastal settlements around the pacific ocean as it’s the biggest and deepest ocean
- Countries within the ring of fire as volcanic activity can also cause earthquakes which lead to tsunamis
- Places near/on destructive plate boundaries
explain the intensity scale for tsunamis
- 12 point intensity scale created in 2001
- Corresponds to current earthquake scale
- Arranged based off a tsunami’s effect on humans, effect on objects (e.g. boats) and damage to buildings\rough correlation with wave heights
- Scale 1: isn’t felt, Scale 12: is a 32 + metre wave which is completely devastating
explain the use of DART for researching tsunamis
DART (Deep-ocean assessment and reporting of tsunamis)
- Sensors on seabed detects crust movement and monitors change in pressure (as small as 1cm tsunamis)
- Data is transmitted to the moored surface buoy which detects wave action
- Transmits data to ground stations and informs at risk areas
- These are in place in the Indian and Pacific Ocean, they use seismic waves to detect undersea earthquakes, they use additional technology as not all earthquakes cause a tsunami
- The more the research available the less the damage (The 2004 Indian Ocean tsunami had not warning systems and 31,000 people died but an early warning system has been in place since 2006)
- Japan has lots of warning systems so when a 9.0 quake struck Japan in 2011, the meteorological agency were ready but part of it failed and so people were not expecting such a large tsunami so they did not prepare or evacuate.
how does an eruption occur at the different plate boundaries?
- They can occur at convergent (destructive) margins where subduction creates friction to then melt the plate at the Benioff Zone. This often happens along the ring of fire (geological fault belt)
- They can also occur at divergent (constructive) margins where magma rises as plates pull apart, e.g. Iceland
- They can occur on hotspots where a hot magma plume breaks a hole in a plate to form new land.
what are the primary hazards of a volcano?
Lava flows
pyroclastic flows
tephra and ash flows
volcanic gases
these tend to have a long geographical reach (pyroclastic flows can travel up to 10,000 km)
explain the primary hazard of lava flows
streams of lava that have erupted on the Earth’s surface. Fast flowing lava can be very dangerous. This depends on the lava’s viscosity which depends on the silicon dioxide content
explain the primary hazard of pyroclastic flows
This is a mixture of hot dense rock, lava, ash and gases which move very quickly along the surface of the volcano. Due to their high speeds, pyroclastic flows are extremely dangerous and can cause asphyxiation for anyone unfortunately caught by the flow.
explain the primary hazard of tephra and ash flows
when pieces of volcanic rock and ash are blasted into the air. This can cause serious damage to buildings, which can collapse under the weight of ash or tephra
explain the primary hazard of volcanic gases
gases like sulphur dioxide and carbon monoxide are released into the atmosphere. Due to their potency, volcanic gases can travel long distances.
what are the secondary hazards of a volcanic eruption?
Lahars
Jokulhlaup
Acid rain
explain the secondary hazard of lahars
combination of rock, mud and water which travel quickly down the sides of volcanoes. These can occur when the heat of the eruption causes snow and ice to melt or alternatively when an eruption coincides with heavy rainfall.
explain the secondary hazard of jokulhlaup
snow and ice in glaciers melt after an eruption which causes sudden floods that are very dangerous, affecting accessibility, transport of aid
explain the secondary hazard of acid rain
caused when gases such as sulfur dioxide are released into the atmosphere.
what are the 3 types of lava?
rhyolitic
andesitic
balsaltic
what is rhyolitic lava like?
- Seen in supervolcanoes, composite volcanoes
- Coolest form of lava at (650-800ºC)
- High silica and gas content, low iron and magnesium
- Formed by melting of the lithosphere and slabs of previously subducted plate
- very viscous with violent eruptions, cataclysmic eruptions
what is andesitic lava like?
- Composite cone locations, Benioff zones (Pinatubo)
- Medium heat of about (800 – 1000ºC)
- Intermediate levels of silica, gas content, magnesium and iron
- Low SO2, high water and hydrochloric acid
- Forms when subducted oceanic plate melts and mixes with seawater, lithosphere and continental plate rocks
- Intermediate viscosity which is slow and traps gases
- Eruption is violent and moderately explosive
what is basaltic lava like?
- Ocean hotspots, shield volcanoes (Kilauea)
- Hottest lava (1000-1200ºC)
- Low silica, water, gases and aluminium, high levels of Co2, Iron and magnesium
- Formed by melting of mantle materials (mostly from upper zone but some from core mantle boundaries
- Eruptions are gentle and effusive
what are shield volcanoes like?
- basaltic lava (less viscous due to less silica) so doesn’t trap gases so not explosive, but effusive
- Shallower gradient due to the lower viscosity of lava meaning it can travel further before cooling (basaltic lava)
- Usually at oceanic hotspots or mid-ocean ridges
- Formed from layers of lava
what are composite volcanoes like?
- Cone volcanoes form from viscous lava (rhyolitic and andesitic) and traps gases so is more explosive
- Usually at subduction zones
- Steep side and formed of layers of lava and ash
- More likely to have pyroclastic flows
what is the way of measuring volcanoes?
Volcanic explosivity index (VEI)
- VEI is a relative measure of the explosiveness of volcanic eruptions done by Chris Newhall
- Classification ranges from “gentle” to “mega-colossal”, scale of 1-8
- It is of no use in connection with non-explosive eruptions of lava
- Volume of tephra ejected, ash cloud height and qualitative observations used to determine the explosivity value
- The scale is logarithmic, increasing by x10 each level
- the greater the VEI, the less frequent the event occurs, e.g. In Hawaii eruptions are happening all the time and they have very gentle lava flows. This makes them more predictable and less threatening.
what is elastic energy in an earthquake?
when a plate is subducted and friction builds to such a point that it exceeds the pressure of the overhead plate causing it to jolt.
what is the focal depth?
the distance between the hypo centre and surface of the earth
what is an intraplate?
when tectonic activity happens in the middle of a plate away from the main boundary
what is a lahar?
saturated soil infused with ash which travels in a channelled motion down a volcano resembling a landslide
what is mantle convection?
when plumes of heated magma rise to the surface and cool, going sideways and sinking at the trenches to be reheated convection currents
what is tectonic strain?
when seismic energy creates pressure and friction
what is a hazard-management cycle?
a theoretical model of hazard management as a continuous four stage cycle involving: mitigation, preparation, response and recovery
what is rapid onset for a hazard?
a hazard that happens very slowly with plenty of evidence and warning (e.g. drought)
what is the pressure and release model?
a tool used to work out how vulnerable a country is to hazard
what is sea-floor spreading?
It is the movement of the oceanic crust away from a constructive (divergent) plate boundary at the mid-oceanic ridge as recorded by the magnetic stripes in the basaltic rock. This causes the spreading of the sea floor.
what is an earthquake in a developed country?
Christchurch earthquake, New Zealand
what are the key facts about the earthquake of Christchurch, 2011
- 22nd February 2011
- happened in the Canterbury region on New Zealand
- the epicentre was 6 miles SE of Christchurch and the focus was very shallow at 3.1 miles
- found on the ring of fire
- 8 on the mercalli intensity scale
how did the Christchurch earthquake happen?
- conservative plate margin along the alpine fault within the ring of fire. the pacific plate moving along Australian plate caused a build-up of friction and elastic energy at a locked fault. as the plates broke free the jolt released a 6.3 magnitude earthquake
- as the land was close to the epicentre, although the magnitude wasn’t that great the power was felt
- hard volcanic rock resulted in seismic waves being reflected towards the surface
what were the key impacts of the Christchurch earthquake?
Primary
- effects of 8 on the Mercalli intensity scale
- 50% of city centre’s buildings destroyed
- 9 million tonnes of crumbled buildings led to illegal dumping and increased land field sites
- 130km of sewage and water pipes destroyed
Secondary
- 185 deaths
- $40 billion in damage
- reduced air quality meant that for 32 days it was below government “safe standards”
- as businesses collapsed employment fell by 6%
- very bad liquefaction occurred due to the wet winter and the fact that many of suburbs are built on soft soil or sand
what were the responses of the Christchurch earthquake?
- governments set up GeoNet to help “quake proof peoples’ homes”
- military called in as additional personnel for search and rescue
- environment recovery programme, led by environment Canterbury
- a recovery assistance centre was also established to field phone calls for organisations such as housing new zealand, the Red Cross and work and income
what is an earthquake in a developing country?
Haiti earthquake, 2010
explain the key facts about the Haiti earthquake
- occurred on the 12th January, 2010 on the West Indian island of Hispaniola, compromising the countries of Haiti and the Dominican Republic. however, the most severely affected was Haiti
- Haiti lies right on the boundary of the Caribbean and North American plates. There was slippage along a conservative plate boundary that runs through Haiti.
- the initial shock was registered at a magnitude of 7 which was shortly fooled by aftershocks of magnitude 5.9 and 5.5
- it was the biggest earthquake since the 18th century
- due to the unconsolidated sediments that Port au Prince was built on, shaking was amplified, increasing its intensity on the mercalli scale
- shallow focus (13km)
what are the key impacts of the Haiti earthquake?
- created $14 billion in damages
- one in four of the civil servants located in the capital were killed
- 80% of schools were closed
- 3.5 million affected by the earthquake
- 220,000 estimated dead
- 1.5 million made homeless
- there were 19 million cubic meters of rubble and debris in port-au-Prince
- Haiti had only one airport, several ports and a few main roads which meant that when they were damaged, crucial aid supplies were prevented from arriving or being distributed effectively.
- in October 2010, a cholera outbreak occurred and as of 2016, it is still ongoing. due to lack of medical supplies and trained healthcare workers it caused it to spread, by 2015 720,000 had been affected
what were the responses from the Haiti earthquake?
- $100 million in aid from the USA, $330 from EU
- 989 business grants were given out
- UNICEF collected $575 million fro various agencies to put towards supporting Haiti
- internationally, $13 billion in aid was donated but most of it remained in the hands of international organisations and governments
- Over ¼ of government officials died and key government buildings were destroyed so they couldn’t successfully organise recovery
- due to the corruption and mismanagement it meant that many organisations were unwilling to channel aid money to the government directly, instead they set up projects themselves there, experts say this hampered Haiti’s ability to become self-sufficient and mean that much-needed money has not gone to local businesses an industries
what is a tsunami in a developing country
the 2004 Indian Ocean tsunami
what are the key facts of the 2004 Indian Ocean tsunami
- December 26, 2004
- earthquake off the coast of Sumatra hat caused the earthquake of magnitude 9
- the thrust of the earthquake heaved the ocean floor by about 15m which sent out shock waves
- greatest fault length of any recorded, spanning a distance of an estimated 1,500 km (longer than US state fo California)
- the waves travelled at speeds of up to 800 km/hr
- some waves of up to 17m
why was the 2004 Indian Ocean tsunami so destructive (vulnerability)?
- earthquake causing tsunami was especially large
- epicentre of earthquake as close to densely populated coastal communities- no time to react
- no adequate warning systems in place, there was no alert issued to people to seek safety
- low lying coastlines of many Indian Ocean countries
- some areas had destroyed mangrove forests along the coast for tourist developments- less natural protection
what were the impacts of the 2004 Indian Ocean tsunami (social, economic, environmental)
Social
- 300,000 people died
- 1.7 million left homeless
- in some villages, 70% of villagers were killed
- in thailand as a result of the destruction of the tourism industry, 120,000 workers lost their jobs
economic
- economies such as fishing, agriculture and tourism destroyed. Sri Lanka experienced 60% of fishing fleet and infrastructure destroyed
- economic cost of over $10 billion
- in thailand, the tourism industry lost $25 million a month
environmental
- ecosystems severely damaged
- most vegetation and topsoil was removed 800m inland
- freshwater supplies contaminated by salt water
responses for the Boxing Day tsunami
- since the tsunami, the Indian Ocean tsunami warning and mitigation system has been formed, to detect seismological changed and provide warnings of approaching waves
- $7 billion of aid was promised by foreign governments
- the British public gave £330 million through charities
- food aid was provided to millions of people from the world food programme
what is the case study for a tsunami in a developed country?
tohuku tsunami, 2011
what are the key facts about the Tohuku tsunami?
- march 11th, 2001
- earthquake of magnitude 9 hit northern Japan
- ‘230,000 people who lost their homes were still living in temporary housing’
- tohuku is a region on the island of Honshu in northern Japan
- happened on a convergent plate margin
- shows an example that some events can still be devastating however much you prepare
what happened at the tohuku tsunami?
- the earthquake struck offshore of Japan, along a subduction zone where two of earth’s tectonic plates collide
- the pacific plate moved beneath the eurasian plate, causing friction and built up energy (elastic strain) is released and causes earthquakes.
what are the impacts of the tohoku tsunami? (SEE)
social
- 18,500 dead
- 127,500 homes destroyed
- for populations in the surrounding areas they faced a 70% higher relative risk of developing thyroid cancer for females exposed as infants and a 7% higher relative risk of leukaemia in males exposed as infants (S)
economic
- $300 billion in damage
- the areas hit lost all commercial activity which caused a domino effect on shortages which was felt all around the world
- Nissans profits fell 15% due to shortages and production disruptions
- decline in japan’s contribution to world industry
environmental
- the radiation from the nuclear power plant contaminated multiple oceans around the world, this made areas around it inhabitable for a long time and led to mass migration (S)
- a 5-foot high wave killed more than 110,000 nesting sea birds at a national wildlife refuge (P)
- the Tokyo electric company said that around 300 tons of radioactive water continues to leak from the plant every day into the Pacific Ocean (S)
early warning systems + response for Tohoku tsunami
- residents in Tokyo received a 1 minute warning before the earthquake hit the city
- japan’s ‘stringent seismic building codes’ and early warning system prevented many deaths, this was by letting the authorities to know to stop trains, factory assembly lines and evacuating people from the impact zones
- people in Japan also received text alerts of the earthquake and tsunami warnings but the tsunami wave was underestimated
- warnings were sent however only for around a 3m wave and so they didn’t evacuate as they though the 10m seawall would protect them
- in several communities, the radio or speaker system did not work because of the blackout caused by the earthquake
Response
JMA have expanded its seismic/tsunami monitoring network by installing broadband seismometers and an offshore tsunami monitoring system, to increase its capability for quicker and more accurate estimations of earthquake magnitude and tsunami
- in April 2011, one month after the event, the central government established reconstruction policy council to develop a national recovery and reconstruction outlook for tsunami-resilient communities
- the government decided a policy of coastal protection such as seawalls and breakwater
what is a volcano in a developed country
Eyjafjallajökull (2010)
what are the key facts about the Eyjafjallajökull eruption?
- seismic activity began at the end of 2009 and slowly increased in intensity until the 20th march 2010 with a small eruption (rated 1 on VEI). more violent eruptions began on the 14th April, 2010
- it disrupted most of Europe when during its second phase of eruptions ejected a massive ash cloud into European air space, created the largest air travel disruption since WW2
how did the eruption of Eyjafjallajökull happen?
- the first phase of eruptions came from the NE side of the volcano which is 1660 metres high. the subsequent eruptions caused the melting of large amounts of ice leading to flooding in southern Iceland, leading to the evacuation of 8000 people.
- on the 18th April lots of volcanic ash and gas was released into the atmosphere which was initially spread out by south eastwards winds across the Faroe island, Norway and northern Scotland. this disrupted aircraft for over a month as the ash plume contains particles of volcanic rock which can clog up and jam aeroplane engines.
- Iceland is on two tectonic plates, the eurasian tectonic plate and the North American tectonic plate. most volcanoes in Iceland are caused by constructive plate margins. magma is stored in the magma chamber until pressure is high enough to push it out the vent, down the volcano.
what were the impacts of Eyjafjallajökull (2010)? (SEE)
social
- residents in southern Iceland were evacuated due to the eruption melting the ice and therefore leading to floods
- it caused flight delays all over the world, leading to a disruption in travel
- 10 million air passengers affected
- 800 evacuated
economic
- the IATA estimated that the airline industry as a whole would lose out on £130 million a day, total loss of £1.1 billion
over 95,000 fights were cancelled which disrupted over 10 million passengers.
- those who deliver stock by plane were badly affected as they couldn’t make any sales as they had no stock to sell, affected economies all around the world.
- nissan declared a suspension in the production of 3 models because supply parts had been disrupted, stopped the production of 2000 vehicles, affecting the wages of employees
- Considerable disruption to tourism and business, with total economic impacts estimated at over $3 billion
- workers were temporarily unemployed (e.g. $2 million per day loss in Kenyan flower exports)
environmental
- Erupted 110 million m cubed of ash in one week up to an altitude of about 9km. the distribution of ash was across main flight paths and airports disrupting European and North American flights due to the prevailing westerly winds in the mid-latitude zone and a stable polar front jet stream during the eruption which directed the ash in the same direction for most of the eruption stage
- Perishable Kenyan agricultural products for the UK rotted in warehouses
- the massive reduction of air travel led to an estimated 1.7 million tons of carbon dioxide from entering the atmosphere
responses of eyjafjallajökull
- the Icelandic Red Cross provided food for the farming population, counselling and psychological support, in particular for traumatised children
- the Netherlands Red Cross set up 1500 emergency beds for those whose flights were cancelled
- airports were closed due to the risk of the ash cloud
- aid was given to anybody physically affected by the eruption
- NCAS scientists work now closely with the met office to monitor and model the ash plume from the volcano using the 2 research aircraft and computer models
- the ash was dug up from the bottom of rivers to make the rivers deeper
what is a volcanic eruption in an emerging country?
mount merapi, Philippines
key facts of the mount merapi eruption
- mount merapi is located in SE Asia in the country of Indonesia, island of Java
- Merapi is a 9551 ft tall mountain located on the ring of fire, forming a composite containing the andesitic lava.
- Merapi is situated at the subduction zone where the indo-australian plate is sliding beneath the Eurasian plate.
- This began an increasingly violent series of eruptions that continued into November.
- The scale of this eruption reached 4 on the volcanic explosivity index (VEI)
- Due to the high content of silica and gas which became trapped, and built up an intensive amount of pressure, its eruption was violent and sudden. The nature of this eruption led to the generation of lava domes which when collapsed causing pyroclastic glows and longer explosions.
what were the impacts of the mount merapi eruption? (SEE)
social
- 200,000 people were made homeless by the eruption and a further 320,000 were displaced
- hygiene and sanitation were poor not only because of the overcrowding of evacuation centres but also the contamination of water supplies
- socio-economic reasoning as people lost their jobs, emerging country based on agriculture (primary) and due to widespread countryside being wiped out, a large proportion of employment was affected than in a developed country
- 353 killed from the initial eruption, further 5000 due to the earthquake that occurred 50km SW to Merapi
environmental
- ash, rock and lava deposited on the side of the volcano were washed down and caused lahars which wiped out many houses
- ash cloud dispersed huge amounts of sulphur dioxide and so an increase in acid rain but also localised breathing difficulties and an international cooling effect
- water supplies contaminated by acidic lava and ash but it did lead to more fertile soils in the area
economic
- $600 million damage
- vegetable prices increased because of damage to crops leading to famine as many could no longer afford food
- planes grounded in Australia due to risk of aircraft damage from ash cloud
- general economic consequences like building damage and paying for evacuation centres
what were the responses to mount merapi’s eruption
- 210 evacuation centres set up
- international aid was offered from organisations such as the red cross
- 1600 people, either voluntary or military were part of the national aid response
- 2682 people were moved to safer homes permanently and is making money available to farmers to help replace their livestock
- formal evacuation centres were eventually set up because buildings, such as schools and government office were needed for their official use
what are the prediction systems for mount merapi
- started to be monitored in 1942 using seismometers some of which are still used today
- Magnetic measurement and tiltmeters have been installed and help to predict as small changes in local magnetic fields have been found to coincide with eruptions and tiltmeters to show the inflation of the volcano as magma rises.
- During the late-mid 1900s many of the stations were deprived of equipment due to a lack of funding yet since then there have been considerable improvements in regards to the supply of new equipment
what is water column displacement?
the movement of a volume of seawater above the point at which the seabed was moved up or down by an earthquake
what is the United Nations definition for a hazard?
a natural process becomes a hazard when people are affected
what is the United Nations definition for a disaster?
a natural hazard becomes a disaster when it affects a vulnerable population causing over 500 deaths
what is the United Nations definition for a mega-disaster?
when over 2000 people die or 20,0000 people are made homeless of if GDP is reduced by 5% or if dependence of aid lasts for over a year
explain dregs model for a natural disaster
it shows that if you were to combine a hazardous natural event with a vulnerable population susceptible to human and economic loss then you will have a disaster
what is the pressure and release model (PAR model)
- risk can be predicted using PAR model and two hazard risk equations
- PAR model is often known as the disaster crunch model
- it resembles a ‘nutcracker’ as pressure increases from both sides, release of pressure tacking vulnerability to reduce the disaster
It states that vulnerability is a process that starts with root causes. These are political and economic systems that control who has power in a society. Through a series of processes called dynamic pressures, these root causes can lead to unsafe conditions. The process from root causes to unsafe conditions is called the progress of vulnerability.
root dynamic unsafe
causes pressures conditions
DISASTER
hazard
- if the area affected is highly vulnerable from a range of social and environmental factors the disaster is more greatly experienced
- e.g. Haiti had a poor political system which is a root cause of vulnerability, this is because the government is highly corrupt and the humanitarian aid funds did not reach the people in their entirety meaning people and businesses could not cover as quickly meaning the disaster was greater
what are the three types of vulnerability in the PAR model?
root causes (governmental) dynamic pressures (people) unsafe conditions (location)
explain the strand of vulnerability of root causes
1) limited access to:
- power
- structure
- resources
2) ideologies
- political system (corruption)
- economic system
explain the strand of vulnerability of dynamic pressures
1) leads to lack of investment into:
- infrastructure
- education (no warning systems in place)
- Training
- Appropriate skills
- Local investment
- Local market
- Media freedom
- medical care
2) macroforces
- Rapid population increase
- Rapid urbanisation
- Expenditure
- Deforestation
- Decline in soil productivity
explain the strand of vulnerability of unsafe conditions
1) Fragile physical environment
- Dangerous locations (landslide prone)
- Unprotected infrastructure (shanty towns)
2) Fragile local economy
- Livelihoods at risk
- Low income levels
- high inequalities
3) Vulnerable society
- Special groups at risk (elderly)
4) Public actions
- Lack of preparedness
- Epidemic disease
what is the hazard risk equation?
risk reduction = (mitigation of hazard x reduction of vulnerability) / capacity to cope
what is risk/damage threshold?
refers to the classing of different natural hazards based off their magnitude and scale of damage.
When a hazard’s magnitude exceeds the risk/damage threshold the hazard is dangerous to the local population. This can be because the population is vulnerable or the hazard has an extremely high magnitude.
explain the five strands of vulnerability
1) Physical vulnerability
- When people live in hazard-prone areas in building that offers little protection, lack of infrastructure
- Action: move away from hazard-prone areas
2) Economic vulnerability
- dependant on the economic stays of individuals and nations so affected by assets
- poor residents do not have to money to afford recovery and preparation
- Action: Introduce housing insurance, compensation
3) Social vulnerability
- When a household or community is unable to support the disadvantaged people within it, e.g. political isolation may exist for the poor, females, elderly and rural residents
- elderly populations are more vulnerable
- high population density
- Action: Government could provide money
4) Knowledge vulnerability
- When people lack education and training and therefore understanding.
- This leads to the lack of warning or evacuation systems in place
- Action: They must educate people on efficient evacuation routes
5) Environmental vulnerability
- lack of natural resource depletion
- resource degradation making settlements vulnerable, those dependant on resources
- high pop density leading to people being forced into riskier areas
- being on plate boundaries
- Action: They must relieve population pressures by creating new services
what do u believe is the greatest initiative for mitigation?
the greatest initiative for mitigation must come from the government as they have the largest influence/power to implement reforms. They also have the money to maximise their effectiveness and strength. For example, individuals may not have the social influence to make their ideas widespread or the money to successfully enforce them.
why was Haiti vulnerable and had a low capacity to cope?
- Poor structural integrity meaning buildings couldn’t maintain their structure leading to a lack of shelter
- Densely populated so inevitably affected more people
- Lack of government stability reduced spending and preparation as people were less equipped and educated to deal with the risks
- On a plate boundary so suffered from environmental/physical vulnerability
why are hazard profiles?
They are a way of comparing two physical processes and impacts that all hazards share.
They can show intensity, frequency, special extent, duration, speed of onset, death toll, recovery rate and damage ($). It can also compare two areas of events.
evaluate the positives of the use of hazard profiles
- they can compare the vulnerability of areas to different hazards in a range of categories and are an easy visual representation
- they can help areas see what they are most at risk of. because of this, they can plan and prepare more efficiently, helping to mitigate the effects when they come
- it is easy to compare the same type of hazard in two different locations because it breaks the event down into a variety of factors
evaluate the negatives of the use of hazard profiles
- it is difficult to compare two different hazards as they have different impacts, e.g. a volcano may have a larger spatial extent like Hawaii but not be very intense whereas an earthquake may be very intense like Hawaii, but have a low spatial extent
- It is difficult to compare two different hazards because it doesn’t provide specific values for factors leaving it somewhat open to interpretation. They have varying impacts and spatial and temporal distributions
what are the pros and costs on using a hazard profile of 1 area with a range of factors on different types of hazard
pros
- see what an area is most vulnerable to, see how an area can defend against the hazards, e.g. droughts have a slow speed of onset so allows for preparation
cons
- doesn’t compare to other area so hard to see development
- Development is not factored into the different scales so it’s hard to see
what are the pros and cons of comparing two different areas for the same hazard
pros
- see how vulnerable an area is in comparison to another area
- similar impacts so easy to visually compare
cons
- only references one hazard which is less useful in a multiple hazard risk zone
use a hazard profile to compare the Haiti and Christchurch earthquake
1) In Haiti, the speed of onset and magnitude were greater yet both were still sudden. But the spatial area was far greater for Haiti
(120 km ² vs 12 km ²)
2) Damage costs were greater in Christchurch but levels of death were higher in Haiti (300,000 vs 181)
what would the main points be for
‘Assess the reasons why some countries are vulnerable than others to tectonic hazards’ (12)
- Physical location
- Government initiatives / community preparedness, social and knowledge vulnerability
- New Zealand on ring of fire and plate boundary
- Haiti is also on a plate boundary
what is governance?
Governance is the sum of the many ways individuals and institutions manage common affairs. It is a root cause of vulnerability.
as developing countries generally have poor governance (root cause) what do they normally also have?
- Poor investment into social development, rapid urbanisation
- Exploitation of the environment (dynamic pressure)
- High inequality, poor building and infrastructure, lack of preparedness (unsafe conditions)
what is economic governance
includes the decision-making process that affects a country’s economic activities and its relationship with other economies. This has major economic implications for equity, poverty and QOL.
what is Political governance
is the process of decision making to create policies, influencing national disaster reduction and planning. The nature of this process and the way it brings together the state, non-state and private. Sector players determined the quality of the policy outcome.
what is Administrative governance
is the system of policy implementation and requires good governance at both central and local levels. It requires functioning enforcement of building codes, land-use planning, environmental risk and human vulnerability, monitoring and safety standards.
how is Haiti vulnerable?
- Colonial powers: military regimes, dictatorship
- Infrastructure needs repair
- 2/3 of the population was unemployed
- Largest income is from remittances
- Former French colony, indebted by 90 million gold franks, didn’t finish paying till 1947
- One of the poorest countries
explain Haiti’s vulnerability of its earthquake based off governance
- Developing country, it is poor and so its limited resources were spent on more immediate issues like disease
- High levels of corruption at both local and national government, leading to a lack of resources and commitment to improve the country’s infrastructure and living standards
- Lack of controls and regulations meant many were in poorly built slum housing. These couldn’t sustain the shaking and so collapsed. The dense urban environment also made it difficult for rescue teams to work efficiently.
- Lack of disaster preparation meant officials didn’t know what to do when the earthquake struck
- Concerns about political corruption and mismanagement meant that many of these organisations were unwilling to channel aid money through the Haitian government directly instead bringing their own things from overseas at huge costs. Experts argue that this has hampered Haiti’s ability to be self-sufficient meaning much needed money hasn’t gone to local businesses and industries
how does development and governance affect the impacts of a tectonic event?
Bad governance = social exclusion, inefficiency, red tape, corruption
Good governance = transparency, engagement, sustainability, decentralisation
how would you answer: “Assess the role of governance in determining the vulnerability and resilience of a community to a tectonic hazard” (12)
- Intro: root cause of vulnerability
- Invest into warning systems
- Can control how safe the buildings are, building and infrastructure
- Reduce inequality in a population and reliance on primary industry
- Increase awareness and educate people on what to do (Egypt)
- Yet arguably a country needs to be developed to have good governance and development controls how resilient the economy is (New Zealand vs Nepal)
- Some hazards will still make a population vulnerable no matter how prepared they are, e.g. Japan
how can population density and urbanisation affect the vulnerability and ability to recover from a hazard?
- High population density not only inevitably means more people are affected but it can also hamper recovery as it can reduce the efficiency of evacuation teams due to a dense urban environment
- The degree of urbanisation is significant. More urban means a higher population density and so more people affected. Often also increases slum housing. However rich urban areas often have more mitigation in place, e.g. cross braising.
- Isolated areas will have trouble recovering and rebuilding as they’re difficult to access, e.g. in the Himalayas helicopters are used which are expensive
what is a multiple hazard zone/hazard hotspot?
A hazard hotspot is an area that can experience multiple hazards ranging from tectonic hazards to hydrometeorological hazards.
They are likely to be areas where plate boundaries intersect with major storm belts and high human concentration in low/medium development areas, e.g. the Philippines, Mexico and Japan
why is the Philippines a multiple hazard zone?
- Located on a (convergent) plate boundary creating major risks from both earthquakes and volcanoes
- Archipelago meaning susceptible to tsunamis
- Climatic hazards due to being in storm belt regions
- Mountainous terrain can lead to landslides. Landslides are common due to steep topography, high levels of deforestation and high rainfall
- Its northern and eastern coasts face the pacific ocean (the world’s most tsunami prone ocean)
- Tropical monsoon climate so is subject to heavy annual rainfalls
- The Philippines has 47 volcanoes, 22 of which are active. This means over 30% of he population lives within 30km of a volcano.
what are human factors that further increases the vulnerability of Philippines to multiple hazards
- Growing population, rapid urbanisation and poverty increases their vulnerability
- Many of the country’s poor live in coastal areas where sea surges, flooding and tsunamis are made worse by poorly constructed housing and infrastructure which lack structural integrity
- 25% of the population live in poverty
what are the challenges of multiple hazards
- One hazard can increase the likelihood of other hazards
- Different hazards happening in a short amount of time can make resilience for government and communities hard as it drains resources and stretches the ability of emergency services to respond
- Operating in a near constant state of emergency
how can hydrometeorological hazards contribute a tectonic disaster
- Heavy rainfall can saturate the ground through infiltration and percolation, decreasing its stability. When the hazard hits it means there is more likely to be landslides.
- Increased amount of water acts as a lubricant making the shaking more intense in the first place
- It can lead to the creation of lahars when there is heavy rainfall at the time of an eruption. Leads to the destruction of homes and access roots, hampering evacuation/rescue missions
- If a storm surge or heavy rain occurs soon after, causing flooding then impacts can be exacerbated (lack of sanitation = disease exposure, lack of food if stores or crops are ruined)
what type of hazard is a landslide
Landslides cross over between the two but is usually classified as geophysical as they involve ground movement.
what has happened to the number or reported natural hazards and what has caused this?
the trend in the total number of reported natural hazards has increased
- between 1994 and 2013, the average number of people dying per disaster was over three times higher in low-income countries than in high-income countries
- despite the falling death toll, there has been a rising economic impact. in the 1990s the economic cost of natural disasters was at average $20 billion per year and between 2000 and 2010 it had increased to average of $100 billion a year
- One of the reasons for the difference in total reported natural disasters vs geophysical disasters is because methods of prediction and detection is greater and so even if the amount has changed that much, technological advancements means more are picked up.
- Moreover, there is a greater population density so more people are exposed
- Climate change has led to more hydrometeorological disasters, both in frequency and magnitude
- warming temperatures have fuelled the hazards making them more powerful, there are changing weather patterns
- Changes to environment as a result of rapid urbanisation means more impermeable surfaces to increase flood disasters, deforestation for this fuels this as there is less interception
what has happened to the amount of deaths, people effected and economic damage from hazards
Deaths, people affected and economic damage from hazards has fluctuated. It has had sudden surges and spikes in seriously damaging events like Haiti or Japan.
Overall deaths, however, appear to be decreasing (exc major events).
Better and earlier warning systems, preparedness and building codes should be decreasing deaths yet this is countered by increasing urbanisation and population density which increases deaths.
what reduces the accuracy of statistics for a hazard?
- no universally accepted definition, Definitions sometimes differ across the world, e.g. the UN says 500 must die for a disaster but others may think the number is lower
- Reported number of deaths might be inaccurate due to indirect deaths following the event (e.g. Haiti had a cholera outbreak)
- Mega disasters upset trends because they are drastically different
- Political bias in reporting deaths, in order to protect their country’s status, no deaths to protect tourism or they may be overstated where aid is concerned (e.g. Thailand after the 2004 tsunami as they didn’t want to damage their tourism)
- No single organisation is responsible for collecting information so often collected in different ways, e.g. GMF or IMF
- Difficulty in collecting statistics especially in low human development areas or remote areas, they go unrecorded. Or in densely populated informal settlements where populations are not properly recorded anyway (Haiti, India, Mexico City)
what are the economic impacts of a mega disaster?
- Countries have to sustain affected countries through their recovery via aid, this places economic strain on countries
- Reduced tourism to that country
- Transport, e.g. Airports
- Damage to crops and agricultural means for the world
- Due to the globalisation of supply chains and production, a mega disaster can have a knock-on effect on the production of a good in several countries, affecting their economies (e.g. Silicon semiconductors made in Japan, affected microchips, affected apple)
- Global financial systems and inter-linked, major disasters affect insurance industries in many countries
why is it difficult for scientists to accurately predict tectonic hazards?
- Very complex processes are at play so hard to pinpoint one thing common to all events to use to predict, e.g. undiscovered plate margins, hotspots and the incertitude on - Based on data gathered from global seismic monitoring networks and historical records
- Hypocentres are typically 15km under the ground, inaccessible in many cases for seismometers to get that deep, this means that they cannot be precise under these conditions
- Changes in rock, water content, local shaking and rock properties change and temperatures increase with depth along the fault.
- Forecasts are less reliable because they are generic in magnitude and can cover large geographical areas, larger earthquakes happen less often so have more time to prepare
what can be done to forecast tectonic hazards?
1) Look for precision and specifics
2) Long term forecasts are more reliable than short term
3) Satellites now monitor crust from space to look for signs of stress building so could improve in the future, this is still not entirely accurate
4) GPS is the new method for giving indications
what is the park hazard response model?
it shows how a country or region 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.
- Used to understand that resilience in the aftermath of a hazard event can vary in different countries
- The model suggest that if you are a developing or emerging country then you are likely to recover to a better QOL than if developed when recovery tends to be normal. This also depends on if it is a one-off incident or if it is likely to happen again.
- The model shows how a hazard will inevitably cause a deterioration in QOL and economic activity but the amount of disruption and time taken to recover varied depending on the success and of relief, rehabilitation and reconstruction
- It is possible to compare the curves of two or more tectonic hazards and gain a better understanding of their relative resilience- what makes one place more resilient than another.
- It allows places at risk to prepare better for future events and understand not just resilience but also risk.
what was the international decade for national disaster reduction (IDNDR)?
emphasised the need to combine ‘tow-down’ technological and governmental approaches with bottom up community and NGO efforts
- This may form part of hazard management cycle with the overall aim to reduce future vulnerability
what was the sendai framework?
- A 15 year, voluntary, non-binding agreement which recognises that the state has the primary role to reduce disaster risk but that responsibility should be shared with other stakeholders including local governments
- Aims to achieve substantial reduction of disaster risk and losses in lives, livelihood, health and assets of businesses, communities and countries
what were the priorities for the sendai framework?
- A 15 year, voluntary, non-binding agreement which recognises that the state has the primary role to reduce disaster risk but that responsibility should be shared with other stakeholders including local governments
- Aims to achieve substantial reduction of disaster risk and losses in lives, livelihood, health and assets of businesses, communities and countries
what were the four priorities in disaster management in the sendai framework?
1) understand the disaster risk
2) ensure a strengthening of governance to manage the hazard risk
3) invest in improving resilience and disatser preparedness
4) ‘build back better’ in the recovery, rehabilitation and reconstruction stages
what are the four parts of the hazard management cycle?
prevention and mitigation
preparation
recovery
response
explain the prevention and mitigation part of the hazard management cycle
- Identifying particular hazards and taking steps to reduce their impact.
- Preventions is minimising the effects of a hazard
- This means that the population is less vulnerable. This can be done by:
1. Zoning
2. Land use planning
3. Developing and enforcing building codes
4. Building protective structures, e.g. tsunami walls
explain the preparation part of the hazard management cycle
- Facilitating the response and providing risk reduction strategies, e.g. evacuation routes, having early warning systems, stockpiling equipment
- Preparation is being ready/getting ready to deal with a hazard
explain the recovery part of the hazard management cycle
- Short term focuses on peoples immediate needs, long term can take years and often reduces future vulnerability
- Providing essential healthcare, proving food/shelter, rebuilding infrastructure
- Recovery is getting back to normal
explain the response part of the hazard management cycle
- Coping with initial problems, main aim is to save lives and reduce economic loss through: search and rescue efforts, evacuations and ensuring critical services
- Response is acting well initially after a hazard
what are the 5 stages of the park model
Pre-disaster
Relief
Rehabilitation
Reconstruction
Stage 1- PRE DISASTER
Occurs prior to the event and shows that quality of life is at its normal equilibrium level.
Stage 2
Where the hazard occurs and, again, at this point quality of life is at normal level.
Stage 3- RELIEF
Where the event has happened and search and rescue is underway. Quality of life drops at this stage and stays low for several hours up to several days depending on the severity of the hazard and the level of development of the region/country.
Stage 4- REHABILITATION
Where relief strategies are underway and there is an organised programme of help. It can take a variable amount of time, from hours and days to weeks and months to reach this stage, but quality of life improves at this time.
Stage 5- RECONSTRUCTION
Refers to long term human response; rebuilding and restoring normality. Quality of life returns to normal and in some cases can be higher than it was originally; especially if the repairs improve on the old infrastructure etc
what is the hazard management cycle?
it is a process in which governments and other organisations work together to protect people from the natural hazards that threaten their communities.
what does hazard management generally focus on?
hazard mitigation
hazard adaptation
what is hazard mitigation?
strategies meant to avoid, delay or prevent hazard events (e.g. land-use zoning, diverting lava flows, GIS mapping and hazard-resistant design and engineering
what is hazard adaptation?
strategies design ed to reduce the impacts of hazard events (e.g. high-tech monitoring, crisis mapping, modelling hazard impacts, public education and community preparedness)
what are three hazard mitigation strategies/modifying the hazard event (before)?
land use zoning
diverting lava flows
GIS mapping
what is land-use zoning? how does it help prepare for earth hazards?
it is a process by which local government regulate how land in a community may be used.
in areas at risk from eruptions, land-use zoning is an effective way to protect both people and property.
in areas at high risk from volcanic eruptions + tsunamis:
- any settlements tend to be limited
- certain types of structures and facilities will be prohibited
- some communities may be resettled (those near shore moved to higher ground for tsunamis)
land-use zoning is common in wealthy countries, but less so in some developing countries, often why it causes more deaths in developing countries.
what is the diverting of lava flows for mitigation?
- methods include building barriers and digging channels to try to divert the flows into safer directions
- while these methods have led to some successes, in general they are fairly ineffective.
this is because: - the path taken by lava is hard to predict making it hard to know where to build the walls and channels
- the terrain has to be suitable (downward slope)
- stopping the lava from flowing towards one community may push it towards another.
what is the use of GIS for mitigation?
GIS can be used in all stages of the disaster management cycle, e.g. to identify where evacuation routes should be placed, or to help with rescue and recovery options
what are the three hazard-adaption strategies/modifying vulnerability and resilience?
high-tech monitoring
community preparedness and education
crisis mapping
explain the use of high-tech monitoring for modifying vulnerability and resilience
- technological monitoring systems for volcanic eruptions, earthquakes and tsunamis allow scientists and others to learn more about these natural processes, to predict them further in advance
- GIS helps to create hazard maps and manage hazards more effectively
- early warning systems use scientific instruments to detect signs that a volcanic eruption or tsunami is about to occur
- mobile-phone technology is used to communicate rapid warnings and coordinate preparation activities. when seismographs detected P waves off japan’s NE coast the Japanese government set out text messages via phones warning of the earthquake
explain the use of crisis mapping for modifying vulnerability and resilience
- concerned about the unfolding crisis in Haiti’s 2010 earthquake due to the lack of good infrastructure, members of Ushahidi set up a map site for Haiti so people could provide info, such as where people were tapped under rubble or where there were food shortages via social media or texts
- these locations are then plotted onto maps and placed online so anyone could see them
- rescue and aid workers quickly began to use these maps- which were constantly being updated to decide how, when and where to direct resources
explain the use of community preparedness and education for modifying vulnerability and resilience
- they need to develop suitable preparedness plans and educate local residents, especially in low-income countries
- enforce building codes aimed at ‘hazard-proofing’ structures
- local knowledge is an important part of community disaster preparedness. during the Boxing Day tsunami, the elders of Thailand’s token tribe noticed unusual sea movements and ordered everyone to run to the hill top. moments later the tsunami struck, only one out of 200 villagers died
- community preparedness tends to be most effective when its formalised, so that efforts can be ongoing and coordinated, e.g. a committee may be formed develop plans.
- this includes organising practise evacuation drills, providing first aid courses and creating lists of vulnerable people who would need assistance
what are the three ways of managing loss after a hazard event
aid
the role of non-governmental organisations
the role of insurance
explain the use of aid for managing loss after a hazard event
this can be emergency aid, short-term aid or longer-term aid.
- aid can be provided as cash, personnel, services or equipment.
- it can be distributed straight to the government of the affected country which then uses it to manage the disaster recovery operation or be controlled by aid agencies or foreign governments.
- it is often criticised lsrgely on the grounds that national and local distribution systems are often inefficient or corrupt, it does not encourage a more bottom-up management of disasters at a local level.
explain the role of non-govenemental organisations for managing loss after a hazard event
NGOs play a critical role in disaster management.
- especially important in disasters where the local gov are struggling to respond or don’t have the resources to do so (Haiti)
- they can provide funds, co-ordinate search and rescue efforts and help to develop reconstruction plans
- many NGOs are involved in all stages of the hazard management cycle and often remain in affected areas for years- helping communities to build up their resilience
explain the role of insurance in hazard management for managing loss after a hazard event
- insurance coverage can help commntities to recover from disasters and provides individuals and businesses with the money they need to repair and rebuild
- yet in many countries, few people have insurance for tectonic hazards. more pressing economic needs take priority over a hazard event that may not actually happen
- in some developed countries like Japan, the government and insurance companies work together to provide insurance for economic losses from disasters.
- with earthquakes, seismologists are working with risk analysts to help the insurance industry calculate premiums and risk. computer stimulations are used to estimate the probability of damage from different scales of earthquake event. volcanic eruptions, however, are easier to predict and to know the potential scale of damage
how does the Tokyo metropolitan government manage the earthquake hazards in Japan?
they have made a manual called “disaster preparedness Tokyo” to help households get fully prepared for an earthquake directly hitting Tokyo and other various disasters
- it is tailored to the various local features of Tokyo, its urban structure and the lifestyles of its residents.
- it contains easy-to-understand info on how to prepare for and respond to a disaster, this can be used in the even of an emergency
what is the difference between collision and destructive boundaries?
Collision boundaries are two continental plates that move towards each other leading the formation of mountains and destructive boundaries are where two different ones go towards each other with the denser one going underneath.
what are micro plates and give two examples
they are small mostly rigid areas of lithosphere, located at major plate boundaries but rotating as more or less independent plates.
- easter micro plate
- Juan Fernandez micro plate
name 4 major plates
Pacific, Eurasian, African, North American
what is slab pull?
This is another explanation for plate movement. This is where older and denser oceanic crust will subduct beneath less dense continental plate. The density of the oceanic plate pulls itself into the mantle. The pulling action drags the rest of the plate with it (first theorised by Dan McKenzie)
what happens at an island arc and give an example of one
happens at convergent (oceanic -oceanic) and creates a string of volcanoes, atoll, this is when lava cools above sea level and creates new land
e.g. the Japanese islands
what is the Wadati-Benioff zone?
it is a sloping plane and is the boundary between an oceanic plate that is undergoing subduction and an overriding continental plate. it is a deep active seismic area in a subduction zone and produces earthquakes.
why was liquefaction such an issue for Christchurch?
Liquefaction affected large areas of Christchurch because many suburbs are built on soft soils or sand. Damage from liquefaction may have been worsened by the high water table from a wet winter.
what is the difference between lava and magma?
Magma is composed of molten rock and is stored in the Earth’s crust.
Lava is magma that reaches the surface of our planet through a volcano vent.
what is resilience?
the ability to protect lives, livelihoods and infrastructure from a destruction, and to restore areas after a natural hazard has occurred
what is aseismic design?
This is when buildings and systems are subject to earthquake exposure. This is done by adding construction principles or structural elements. They may use features like shock absorbers, a reinforced steel structure and counterweights. These structures will then, if done effectively, protect against the largest earthquakes.
explain the cause of a tsunami from sub-marine earthquakes
they can be caused by sub-marine earthquakes at subduction zones as a result of sea-bed and water displacement
what can influence the vulnerability and resilience of an area to a hazard?
Inequality of access to education, housing, healthcare and income opportunities can influence vulnerability and resilience.
what is the interaction of physical factors and the significance of context in influencing the scale of disaster
two events in different places can occur with very similar physical factors but if the context of the area is different then they can have very different scales of effects.
context includes development and governance
Haiti and Christchurch had very similar physical factors with their magnitudes being very similar but due to the difference in context of the two places they had very different effect.s Haiti has a poor and corrupt government whereas new Zealand have a strong governance system. this means that aid was funnelled well to Christchurch but for Haiti, money was lost and lots of aid was refused to go directly to the government but instead aid projects were set up, leading to a loss of money for the government.
Haiti had a lower economic impact than New Zealand due to the different levels of development
Iceland being so close to Europe meant the ash cloud had a greater effect stopping northern trans Atlantic flights
Area of Banda Aech (Indian Ocean tsunami) was a low lying area meaning the tsunami could wash far inland
How do u interpret spearman’s rank?
- gives a number closer to one. The closer to one the stronger the correlation, a minus number demonstrates negative correlation.
- first stage is to write a hypothesis (the higher this..this will decrease)
- next is null hypothesis (there is no relation between … and …)
what are convection currents?
This is what pushes the plates. They occur within the molten rock in the mantle and act like a conveyor belt for the plates.
Radioactive elements in the core of the earth decay which produce a lot of thermal energy. This causes the lower mantle to heat up and rise, as the magma rises it cools down and becomes more dense and begins to sink back down to the core. This continuous cycle are convection currents.
Why was liquefaction such an issue for Christchurch?
Because they had a very wet winter and many of the suburbs were built on soft soil or sand.
Which plate movement was responsible for the Tohoku earthquake?
It happened on a convergent plate margin where the pacific plate moved beneath the eurasian plate
How does a volcano form?
It forms when magma from the earth’s interior is able to make its way to the surface, via a vent. This is usually associated with plate boundaries. A volcano can either be a shield volcano or a composite volcano.
explain the origins of the mid-atlantic ridge
The Mid-Atlantic Ridge was formed through a constructive boundary. It is in effect a submerged mountain range made up largely of extruded basaltic rocks. In places, the volcanic mountain rise above the ocean surface as islands. So the hazards are volcanic eruptions and occasional earthquakes.
what is the difference between magnitude and intensity of an earthquake
- The magnitude of an earthquake is measured through the moment magnitude scale (MMS) and relates to the amount of movement or displacement in the earth’s crust and to the amount of energy released. - However the intensity of an earthquake is measured through the Mercalli scale and is a measure of the amount of ground shaking. This is a critical factor affecting the amount of damage than an earthquake causes.
- They measure different aspects of an earthquake. Both are significant as factors affecting the potential scale of earthquake damage.
what is vulnerability in the context of hazards?
The likelihood of a community being unable to absorb and recover from the impacts of a hazard. This can be social, economic or physical vulnerability.
what is meant by resilience in the context of hazards?
This is the ability of a community to cope with the effects of a hazard
how does the Richter scale and moment magnitude scale differ?
The Richter scale measures the magnitude of an earthquake and the height (amplitude) of an earthquake’s shock waves whereas the moment magnitude scale measures from the energy released by an earthquake, usually in terms of the amount of fault slip.
The richter and MMS scales are logarithmic, so that an increase of 1 on the scale indicates an earthquake that is 10 times as powerful.
name the six characteristics that are commonly used in producing a tectonic hazard profile
Magnitude Speed of onset predictability Frequency Duration Areal extent of damage
Identify the inequalities that make low-income households and communities carry a disproportionate share of disaster ‘costs’
- Asset inequality (lack of proper housing and means of livelihood; difficult to recover from any loss of limited assets)
- Access to service inequality (education, healthcare, policing)
- Political inequality (not able to fight their corner or protect their interests)
- Social status inequality (lack of status also means an inability to reduce inequalities)
identify two ways in which disasters can create development opportunities
- the willingness to invest in hazard mitigation so the future hazard events cause less disruption
- the need for reconstruction offers a great opportunity to start fresh (e.g. better housing, new businesses, new development directions) giving the area a function that was previously lost from the disaster (loss of agricultural function)
what is the pressure and release model trying to show?
It suggests that socio-economic context of a hazard is important. In poor, badly governed (root causes) places with rapid change and low capacity (dynamic pressures) and low coping capacity (unsafe conditions), disasters are likely. It shows how root causes, dynamic pressures and unsafe conditions combine with a natural hazard to create a disaster.
what is meant by the word risk?
the probability of an event occurring that could potentially harm people, damage property of destroy infrastructure. low probability events can nonetheless pose a high risk if their magnitude is very large
give 5 factors which can increase vulnerability to earth hazards
- living in a hazard-prone areas in buildings that offer little protection (physical vulnerability)
- when people lack education and training and therefore understanding (knowledge vulnerability)
- due to population pressure it leads to people being forced into riskier areas, high density pop (social vulnerability)
- when people have little money, at risk of losing their jobs, cannot afford good protection measures (economic vulnerability)
- lack of government stability reduces spending and preparation so people are less equipped (political vulnerability)
How can governance affect vulnerability?
- high levels of corruption at both local and national government leading to a lack of resource and commitment to improve the country’s infrastructure
- lack of controls and regulations means many are left in poor slum housing, cannot sustain shaking
- lack of disaster preparation means that officials don’t know what to do when an earthquake strikes
- high corruption means that some organisations will be unwilling to channel aid money through the gov directly, hampering their ability to be self-sufficient, HAITI
explain the importance of physical context in influencing the scale of a disaster in christchurch
- many of the suburbs are built on soft soil or sand and through their wet winter it led to them suffering from very bad liquefaction
- the epicentre was 3 miles from the city centre of Christchurch, high pop density, 50% of city centre’s buildings destroyed, $40 billion in damage
explain the importance of physical context in influencing the scale of a disaster in Haiti
- on a plate boundary so suffered from environmental/physical vulnerability
- it had a shallow focus (13km) which increased the amount of ground shaking
- looser soils caused many building foundations to sink through liquefaction
- the epicentre was only 24km from the country’s capital and its most densely populated city
explain 2 pre disaster and 2 post disaster strategies for earthquakes
Pre disaster
- high-tech monitoring
- hazard-resistant design and engineering
Post disaster
- crisis mapping
- AID
what is aseismic design?
- Technology can also help construct buildings that are more hazard resistant, earthquake-resistant structures are intended to withstand the largest earthquake of a certain probability that is likely to occur at their location
- after the Christchurch earthquake, governments set up GeoNet to help “quake proof peoples’ homes”
- this includes the use of automatic window shitters to prevent falling glass, steel frames which can sway during earth movements, open areas where people can assemble if evacuated and rubber shock-absorbers to absorb earth tremors
what do the USGS do?
The USGS are a team of scientists that are responsible for providing information to support readiness and preparation for hazards. They work with lots of people to understand hazards and communicate their potential risks and impacts. They use storm-tide sensors (hurricaines) and other pieces of equipment to provide scientific data to inform ways to mitigate large-scale loss of life and property.
Explain 3 structural and 3 non-structural management strategies for volcanoes and earthquakes.
Structural:
Diverting lava flows- methods include building barriers and digging channels to try to divert the flows into safer directions
Aseismic design- earthquake-proof buildings are constructed to reduce the potential impact. They may use features like shock absorbers, a reinforced steel structure and counterweights
Earth embankments- can be built around a volcano to try divert the flow of magma
Non-structural:
GIS mapping
Land-use zoning
Community preparedness and education
what are 5 characteristics of a mega-disaster?
large spatial scale High Magnitude Strong likelihood of needing international support from NGOs and IGOs Large economic and human impacts Low probability
give two examples of a tectonic mega-disaster
Haiti 2010 earthquake
2010 Eyjafjallajökull
given 3 examples of how different types of natural hazards may be linked
If an earthquake occurs in the ocean then it may trigger a tsunami to occur through the seismic waves jolting the sea waves.
Landslides triggered by earthquake shock waves can be aggravated by the torrential rains of a tropical storm.
Volcanic eruption under ice can cause sudden melting and flooding (Jökulhaups)
why is there concern about the world’s rapidly-growing mega-cities
- high population density meaning more people will be affected
- the increase in informal settlements that it creates
- immense pressure on services (healthcare) in times of disaster
- many are located in hazard-prone or multiple-hazard zones
what does the risk disk model attempt to explain?
It attempts to explain the decline in disaster deaths in terms of preparedness, mitigation, response and recovery.
explain the role of scientists as players when dealing with tectonic hazards
Scientists play a key role in the prediction and forecasting part of the hazard. They must have accurate predictions as to when the hazard will hit and the scale. They are responsible of warning us of the hazard in order to effectively prepare prior to the event.
Volcanologists are now better able to forecast both aspects (where and when)
give 5 examples of the human factors affecting the response to a tectonic hazard
- Tectonic hazard education/training
- Population density
- Scientific understanding
- Infrastructure
- Quality of governance
what is a mitigation strategy?
This is a strategy that takes place before the disaster hits. It involves preparing a set of actions and steps aimed at reducing the impact of a hazard event and/or the probability of its occurrence.
give an example of a micro approach to improving protection from both earthquakes and volcanoes
Earthquakes: strengthening individual buildings against stress and shock waves
Volcanoes: diverting lava flows
insuring buildings
give 3 examples of a macro approach to improving protection from tsunamis
Creating coastal buffers in the form of mangroves or some other form of dense shore vegetation.
Building defensive walls.
Land-use zoning- moving housing and other important uses (hospitals, transport lines) away from the most vulnerable areas.
explain the role of planners in managing the impacts of tectonic hazards
they have two distinct contexts. The one to modify the potential impacts of the event by land-use zoning and improving prediction and warning systems. They also need to improve preparedness through emergency action plans and educating the locals.
give three players that are involved in the managing of the impacts of tectonic hazards
planners
insurers
NGOs
explain the role of insurers in managing the impacts of tectonic hazards
they need to make sure they have plans in place to help all those who are insured with them which will mean that the social impacts will be minimised through the loss of housing. They reduce the financial burden for those with insurance premiums, so little use to the poor.
explain the role of NGOs in managing the impacts of tectonic hazards
they need to make sure they have preparation in place in order to distribute aid in the most effective way.
They ensure that the social impacts are minimised through the giving of food and through the economic aid they minimise the financial impacts. They also educate about hazard risks and what to do during a hazard event.
