Hazards 3- Case studies Flashcards
(50 cards)
What are the different impacts of hazards on developed and developing countries?
Developed countries:
-Incur higher damage costs because there are more expensive buildings and infrastructure to be damaged (insurance and repair costs also high).
-Even small costs create problems for the poor.
Developing countries:
-Incur higher death rates because people are more vulnerable, lack awareness of hazards, live in buildings that haven’t been proofed, and don’t have access to communications, decision-making, or emergency services.
Hazard event profile for Haiti and Christchurch earthquakes
Characteristics and impacts of tectonic hazards
-Spatial predictability: An area that has never had an event will experience greater impacts as people and places will be unprepared
-Areal extent: The larger the area affected by the event, the greater the impacts will be, as more people and places will be affected
-Frequency: An event that occurs often is likely to create cumulative impacts (although rare events will have more energy)
-Magnitude: The greater the magnitude of energy released by an event, the greater the impacts are likely to be
-Speed of onset: The faster the event occurs, the shorter the warning time and the greater the impacts as places are unprepared
-Duration: the longer an event last, the more likely that there will be greater impacts
What are the characteristics of events that present the highest risks?
-Have high magnitude and low frequencies
-Have rapid speeds of onset with spatial predictability
-Have a large areal extent
-Tend to occur at subduction zones & collision zones.
The Pressure and Release (PAR) model
2010 Haiti Earthquake- tectonics and geography
Tectonics = earthquake (conservative boundary)
Geography:
-Epicenter close to capital Port au Prince (25km away), focus shallow (only 13km)
-Spatial extent quite large (120km2)
-Hadn’t experienced an earthquake in 150yrs, so no experience,
-Magnitude 7,
-Speed of onset = sudden ( 30-60 seconds),
-Predictability: none (known fault).
2010 Haiti earthquake secondary hazards
-Over 45 aftershocks > 4.5 and two aftershocks of 5.9 and 5.5 within a few days and 5.9 on the 20 January.
-One town experienced a localized tsunami
-Liquefaction in the port area.
2010 Haiti earthquake- living conditions and pressures
-Living conditions = Buildings & infrastructure not earthquake-proof, high unemployment, relied on the informal sector, many lived in slums, 72% lived in poverty, homes built on slopes.
-Pressures = rapid rural to urban migration, growth of slums..all put pressure on local authorities. Hillsides stripped of trees to make more space. Low HDI. Education levels are lower, so perception & risk were low.
2010 Haiti earthquake- contribution of poor governance
-Basic needs were not being met -limited access to roads, electricity & sanitation.
-Poor planning – deforestation & building on hillsides, no preparedness, didn’t ensure correct building codes, corrupt government.
-Access to health care & education is poor.
-Low-income groups lack a ‘safety net’ after a disaster – personal one ( savings, food) or government one ( social security, aid, free healthcare)
Statistics about Haiti in 2010
-One the poorest countries in the world.
-54% abject poverty & 20% GDP from remittances.
-6 months after the event, 98% of the rubble remained uncleared.
-1 in 5 jobs lost.
-80% of schools were destroyed and 25% of civil servants died.
-2017 – 55,000 still in temporary camps.
-2 years after, only 43% of aid was received.
When was the Haiti earthquake?
2010
When were the Christchurch, New Zealand, earthquakes?
2010 and 2011
Christchurch earthquake tectonics and geography
Tectonics = earthquake (conservative boundary)
Geography:
-Epicentre was close to Christchurch (2010- 40km away & 2011 only 10km),
-Shallow focus – only 10km in 2010 and 5km in 2011
-Spatial extent 12km2
-Earthquakes normally occur every 55 yrs
-Magnitude 7.1 & 6.3
-Speed of onset = sudden ( 30-60 seconds),
-Predictability: none ( 100 faults in the area, margin complex/changing).
Christchurch earthquakes- secondary hazards
1st large earthquake in 2010, 11,000 aftershocks continued into 2012, 26 aftershocks were 5+ magnitude and x2 +6 magnitude.
Christchurch earthquakes- trigger quake
-Led to 6.3 magnitude earthquake on 22 Feb 2011.
-Liquefaction in the city built on the edge of Canterbury plains, which are made of loose river deposits.
-Caused upwelling of 400,000 tonnes of silt.
Christchurch earthquake- seismic lensing
-Seismic waves travelled through soft rocks and then bounced back of hard basalt rocks, causing further shaking
Christchurch earthquakes- living conditions and pressures
Living conditions
-Those living in Port Hills suffered from large rock fall.
-Many buildings had already been weakened by previous quakes.
-If it wasn’t for the strong building codes, most of the city would have been flattened due to shaking & liquefaction.
Pressures
-Didn’t experience the extra pressures like Haiti.
-Schools had been carrying out regular drills ‘the turtle) since the 2010 earthquake.
-Workplaces & schools had strict emergency plans & emergency services were well prepared.
Christchurch earthquakes- causes
-Didn’t suffer from poor governance or from a weak economy or cultural issues.
-NZ is well prepared for earthquakes, but the Greendale fault was unknown until it was revealed after the Darfield 2010 quake.
-The only vulnerability lay in the living conditions, which was due to the 2010 earthquake had already weakened structures. The city didn’t have the time to strengthen & rebuild before the 2011 quake.
Christchurch earthquakes- responses
-Temporary housing & portable toilets were supplied, a full emergency plan was in place within 2 hours.
-Vulnerable people were well looked after. Schools amalgamated to ensure provision continued. Farmers helped to remove rubble.
Hazard profile for Haiti 2010 and Christchurch 2011
Table comparing the impacts of Haiti and Christchurch earthquakes
When was the Volcan de Fuego eruption?
2018
Vulcan de Fuego type of margin
Destructive
Vulcan de Fuego plate margins diagram
