tectonics paper 1 Flashcards
1.4 impacts of volcanic eruptions
PRIMARY
Pyroclastic flows - mixture of hot rock, lava, ash and gases; dangerous and can move fast; destroy building
Tephra- volcanoes eject material such as rock fragments
Lava flows - streams of molten rock; fast flowing lava can be very dangerous
Volcanic gasses - explosive eruptions -co2 -carbon monoxide etc - most deaths from this
SECONDARY
Lahars - volcanic mudflow, rock and water. The degree of the hazard varies depending on the steepness of slopes, the volume of material and particle size. associated with heavy rainfall as trigger as old tephra deposits on steep slopes can be re-mobilised into mudflows
incorporate anything in their path; very fast and carry alot and far
Jokulhlaups – glacial outburst flood. hazard to people and infrastructure. occur very suddenly with rapid peak discharge of large volumes of water, ice and debris from glacial source.
volcanic case study
2010 Eyjafjallajökull (Iceland)
2010 Eyjafjallajökull (Iceland)
Constructive margin, Composite cone volcano, VEI = 4
Social Impacts: no injuries, no deaths, job disruptions less money made, breathing problems due to ash,
Economic Impacts: Major disruption to European and transatlantic air travel affecting 10 million passengers, $10 million economic loss, imports/ exports stopped e.g. fruit from Africa
Environmental Impacts: Ice melt on the volcano caused some flash flooding, no air traffic meant 3million tonnes CO2 less emitted, ash created fertile land for agriculture
1.4 impacts of earthquakes
PRIMARY
ground shaking & crustal fracturing
Building collapses
Ground splitting
SECONDARY
Soil liquification: water within the soil separates from soil particles and rises to the surface; causes soil to act like liquid; buildings eventually collapse
Landslides: where slopes weaken and fail. As many destructive earthquakes occur in mountainous areas, they can be a major impact.
developed earthquake case study - Japan Tohoku 2011
Tohoku 2011 Earthquake ( & tsunami)
magnitude 9
9.3m tsunami
16k deaths, 300bn damages, 300k buildings destroyed
tsunami damaged Fukushima Nuclear Plant - released dangerous levels of radiation in the air so 47,000 evacuated
contaminated water in fishing grounds - damaged ecosystems
vulnerability - preparation:
75% earthquake proof buildings, drills, advanced warning systems, school training, regulated land use.
response:
110,000 defence troops had been deployed, radio and TV stations switched to earthquake coverage and told people what to do
Bank of Japan offered $183 billion to Japanese Banks s economy could keep operating
accepted aid and help from 20 countries
emerging earthquake case study - Sichuan China 2008
Sichuan 2008
magnitude 8, 19km depth
70k deaths, $60bn damages, Major pollution, landslides affected people and biodiversity. roads damaged slowed relief.
vulnerability:
Poor building regulations, Corrupt gov, Isolation, No prep
response:
quick, 140,000 soldiers sent, volunteers, temporary camps, 40,000 people to homes in a new city made within 2 years,
developing earthquake case study - Haiti 2010
Port au Prince city
magnitude 7, 13km depth
220k deaths, 3m effected, Cholera outbreak, $16bn aid
Global connections destroyed (ports and airports) - slow relief
vulnerability prep:
Red Cross already present
No preparations
Haiti failures: Corrupt gov, Failed building regulations, Slums, 60% below poverty line, no drills,
1.6 a. Inequality of access to education, housing, healthcare and income opportunities can influence vulnerability and resilience.
nepal vs japan
Vulnerability
- Physical Vulnerability - living in a hazard prone area with little protection
- Economic Vulnerability - people risk loosing employment, wealth or assets during hazards
- Social Vulnerability - communities unable to support most vulnerable, leaving them at risk
- Knowledge Vulnerability - lack of training and warning causes higher risk
- Environmental Vulnerability - communities risk increases due to population density
Places with very low human development = vulnerability is very high
as people lack basic needs of sufficient items, housing is informally constructed, education rates are lower, healthcare access is limited
NEPAL VS JAPAN
developing: Nepal Gorkha Earthquake 2015
magnitude 7.9
9,000 deaths, 22,000 injured
Economic losses of US$5 billion
Landslides/avalanches down steep mountain slopes - killing 20 people on Mt. Everest
Rural villages destroyed - 450,000 destroyed homes
2.8 million+ displaced from Kathmandu
Increase in sex trafficking
Nepal is a mutliple hazard zone with a steep mountain landscape -> exposed to landslides, debris and floods and earthquakes
Poor and socially excluded groups are less able to absorb shocks than well-positioned and better-off households
Immediate response
1 million needed food
slow relief @ Himalayan Mountains bcs of altitude
Gender discrimination - thousands of women without aid
‘Tent City’ at the Kathmandu airport
Long-term
Asian Development Bank - US$200 million for rehabilitation and reconstruction
Aid from UK ($73m)
developed: Japan Tohoku 2011 Earthquake ( & tsunami)
magnitude 9, 9.3m tsunami
16k deaths, 300bn damages, 300k buildings destroyed
tsunami damaged Fukushima Nuclear Plant - released dangerous levels of radiation in the air so 47,000 evacuated
contaminated water in fishing grounds damaged ecosystems
Nissan’s full year profits dropped 15% as a result of shortages and production disruptions because of the disaster
vulnerability - preparation:
75% earthquake proof buildings, drills, advanced warning systems, school training, regulated land use.
response:
110,000 defence troops had been deployed, radio and TV stations switched to earthquake coverage and told people what to do
Bank of Japan offered $183 billion to Japanese Banks s economy could keep operating
accepted aid and help from 20 countries
1.6 b. Governance and geographical factors influence vulnerability and a community’s resilience.
Governance: the process by which a country or region is run (how well a place is run)
It has large impacts on coping capacity with natural disasters:
- Planning
- Management
- Corruption
Geographical Factors
Population Density: high populated areas are hard to evacuates like Mt Vesuvius in Italy
Degree of Urbanisation: when major cities are struck, death tolls are very high e.g. Japan
Accessibility: Rural areas are difficult to get relief and aid to e.g. Nepal. Urban areas have more assets than rural area so are better at coping. However high population density increases risk
1.6 c. Contrasting hazard events in developed, emerging and developing countries to show the interaction of physical factors and the significance of context in influencing the scale of disaster.
In developed countries major death tolls from tectonic hazards are rare. The 2011 Tohoku earthquake and tsunami in Japan is very much exceptional in terms of impacts.
Countries such as Japan, the USA and Chile have:
- advanced and widespread insurance, allowing people to recover from disasters
- government-run preparations such as Japan’s Disaster Prevention Day on 1st September each year, as well as public education about risk, coping, response and evacuation.
- sophisticated monitoring of volcanoes and, where possible, defences such as tsunami walls
- regulated local planning systems, which use land-use zoning and building codes to ensure buildings can withstand hazards and are not located in areas of unacceptable risk.
Developing Haiti, Port-au-Prince - HDI 0.48 160,000 deaths, 1.5 million homeless 250,000 homes destroyed Context Decades of corrupt, ineffective and brutal governance left Haitian people hugely vulnerable because of slum housing, ineffectual water supply and endemic poverty. A post-earthquake cholera epidemic has killed more than 10,000 people and infected more than 800,000.
Emerging Sichuan, 2008, 0.73 69,000 deaths 375,000 injured Economic costs of $140 billion Context Economic losses in China were high, reflecting its development progress since 1990, as it destroyed formal homes, businesses and infrastructure. The immediate response was rapid because the 2008 Beijing Olympic Games were only months away, so the Communist government mobilised the army and other responders rapidly.
CASE STUDIES : 2010 Haiti, 2008 Sichuan China, 2011 Tohoku Japan.
1.8 a Prediction and forecasting (P: role of scientists) accuracy depends on the type and location of the tectonic hazard.
Forecast: probability that something might occur in a particular place at a certain time. Less precise than prediction, and provides a percentage change of a hazard occurring (e.g. a 25% of a magnitude 7.0 earthquake in the next 20 years). It allows people to be prepared e.g. evacuate and encourages governments to better building regulations in high-risk areas.
Prediction: knowing when and where a natural hazard will happen. This is only useful on a spatial and temporal scale that can be acted on (evacuation)
Earthquakes - cant be predicted. only forecasted
Only areas at high risk can be identified (risk forecasting), and areas that are likely to suffer severe ground shaking and liquefaction; this can be used for land-use zoning purposes
‘Seismic gaps’, i.e. areas that have not experienced an earthquake for some time and are ‘overdue’ can point to areas of high risk
Volcanic eruptions - can be predicted
monitoring equipment on volcanoes measures changes as magma chambers fill and eruption nears.
Tiltmeters and strain meters record volcanoes ‘bulging’ as magma rises and seismometers record minor earthquakes indicating magma movement
Gas spectrometers analyse gas emissions which point to increased eruption likelihood.
The minimal death toll from volcanic eruptions (despite 60-80 eruptions per year) is due to improved prediction.
Tsunami - can be partly predicted
An earthquake-induced tsunami cannot be predicted. However, seismometers can tell an earthquake has occurred and locate it, then ocean monitoring equipment can detect tsunami in sea, people are then evacuated from coastal areas.
In many developing countries, volcano monitoring and tsunami warning may not be as good as they could be due to cost of technology. Also, its more difficult to reach isolated, rural locations with effective warnings.
1.8 b. . The importance of different stages in the hazard management cycle (response, recovery, mitigation, preparedness). (P: role of emergency planners)
hazard management cycle: shows different stages of managing hazards
stage 1: Preparedness - being ready for the hazard
stage 2 - Response - immediate action after event
stage 3: Recovery - returning to normal, long term response
stage 4: Mitigation - strategies to reduce future effects
1.9 a. Strategies to modify the event include land-use zoning, hazard – resistant design and engineering defences as well as diversion of lava flows.
Modify the event - BEFORE the hazard strikes (long term)
Mitigate the impacts of the hazard, by reducing its areal extent and/or effective magnitude
This is the most desirable type of management, but isn’t always possible. It relies on technology and planning systems which can be high cost, so is less likely to be used in developing and emerging countries.
Land-Use Zoning
This is preventing people from building: on low-lying coasts (at risk from tsunami and flooding), close to volcanoes , on areas of high ground-shaking and liquefaction risk
Advantages: Low cost, Removes people from high-risk areas
Disadvantages: Prevents economic development on some high-value land, e.g. coastal tourism, Requires strict, enforced planning rules.
Aseismic Buildings
Buildings that are strong enough to resist (most) earthquakes, and prevent damage. includes cross-bracing, reinforces structures, deep foundations of stone, and made from rubble, hollow concrete bricks designed to cause minimal damage, cement concrete roof, reinforced steel corner pillars to provide strength and flexibility
Tsunami Defences
Tsunami sea walls and breakwaters, which prevent waves travelling inland.
Advantages: reduces damage, a sense of security
Disadvantages: Can be overtopped, Very high cost, Ugly and restrict use/development at the coast
Lava Diversion
Channels, barriers and water cooling used to divert and/or slow lava.
Advantages: Diverts lava out of harm’s way, low cost
Disadvantages: Only works for low VEI basaltic lava, The majority of ‘killer’ volcanoes are not of this type. not always effective
1.9 b . Strategies to modify vulnerability and resilience include hi- tech monitoring, prediction, education, community preparedness and adaptation. (F: models forecasting disaster impacts with and without modification)
Modify the vulnerability - BEFORE the hazard strikes (short term)
Get people out of the way of the hazard, or help them cope with its impacts by building resilience.
Hi-Tech Scientific Monitoring (used for Prediction)
monitors volcano behaviour and predict eruptions.
Advantages: predicting an eruption is possible, Warnings and evacuation save lives
Disadvantages: Costly, so not all developing world volcanoes are monitored, if predictions (and evacuation) are wrong, people are less lively to believe the next one, Does not prevent property damage
Community Preparedness and Education
e.g. preparation days, education in schools and earthquake kits. These are boxes of essential household supplies (water, food, battery powered radio, blankets) kept in a safe place at home to be used in days after an earthquake.
Advantages: Low cost, often implemented by NGOs, Can save lives through small actions
Disadvantages: Does not prevent property damage, Harder to do in isolated rural areas
Adaptation
Moving out of harm’s way and relocating to a safe area.
Advantages: Would save both lives and property
Disadvantages: High population densities prevent it, Disrupts people’s traditional homes and traditions
1.9 c Strategies to modify loss include emergency, short and longer term aid and insurance (P: role of NGOs and insurers) and the actions of affected communities themselves.
Modify the loss - AFTER the hazard strikes (short and long term)
Reduce the short- and long-term losses by acting to aid recovery and reconstruction
The least desirable form of management, because it implies that a disaster has occurred and caused damage to people and property.
Short-term Emergency Aid - search and rescue followed by emergency food, water and shelter.
Advantages: Reduces death toll, saves lives, keeping people alive until longer-term help arrives
Disadvantages: High cost, hard to distribute in isolated area, limited services and low quality in developing countries
Long Term Aid: form of reconstruction plans to rebuild an area and improve resilience.
Advantages: Reconstruction can ‘build in’ resilience through land-use planning and better construction methods
Disadvantages: Very high costs, Needs are forgotten by the media after the initial disaster
Insurance: compensation to people to replace losses.
Advantages: Allows people to recover economically by paying for reconstruction
Disadvantages: Doesnt save lives, Few people in the developing world have insurance.
