HAZARDS: Seismic Hazards - Impacts and Responses Flashcards
Can earthquakes be predicted?
Not really - it is very difficult.
- Regions at risk can be identified, though.
- But attempts to predict a few hours before the event are questionable - relying on monitoring groundwater levels, release of radon gas and unusual animal behaviour.
Discuss the prevention of earthquakes:
- Not possible to prevent currently.
- Can prevent risk to people:
- No building on land prone to liquefaction
- Sea walls - protection from tsunamis.
- However, have been some suggestions to stop plates sticking to each other and allowing for smooth movement:
- Eg. lubricating with water or oil.
How can structures be made hazard-resistant?
- Large concrete weight on top of building - moves with the aid of a computer programme in the opposite direction to force of the earthquake to counteract the stress.
- Shock absorbers in foundations - allow some movement of the building.
- Cross-bracing - hold it together better when it shakes.
- Older buildings and structures can be retrofitted.
How can people be educated about seismic events?
- Instructions about how to prepare by securing homes, appliances and heavy furniture and assembling ‘earthquake kits’.
- Children have quake drills at school.
How can fires caused by seismic events be prevented?
- Installation of ‘smart meters’ that can cut off gas if quake of sufficient magnitude occurs.
Explain land-use planning in terms of prepardness for a seismic event:
- Most hazardous areas can be identified and regulated in terms of land use.
- Certain types of buildings should be put in low risk zones, eg school and hospitals.
Name a seismic event in a LIC:
Eathquake in Haiti, January 2010.
Describe the 2010 Haiti earthquake:
- Depth of 13 km.
- Magnitude 7.0 MMS.
- Epicentre was 25 km west of capital, Port-au-Prince.
- At least 50 aftershocks measuring 4.5 or greater recorded.
Why was Haiti vulnerable to hazards?
- Poorest country in the western hemisphere.
- Long history of national debt, extreme poverty and poor housing conditions.
- Lies at junction between NA plate and Caribbean plate between two fault zones, one of which runs directly beneath Port-au-Prince.
- Also vulnerable to tropical cyclones.
What were the major social effects of the 2010 earthquake in Haiti:
- Estimated death toll of around 160,000.
- Around 300, 000 injured.
- 2.3 million left homeless
- Collapse of water supplies, lack basic sanitation and thousands of unburied bodies led to disease spreading - massive cholera outbreak.
What were the major economic effects of the 2010 earthquakes in Haiti?
- Built environment and businesses destroyed - expensive to repair.
- Prison destroyed - escape of 4,000 prisoners.
- Vital infrastructure destroyed, eg roads blocked by falling trees etc - expensive to repair the damage.
- Communications infrastructure destroyed.
- Hospitals and medical facilities damaged.
- Education system collapsed - 1300 schools and universities destroyed, limiting development of country.
What were the major political effects of the 2010 earthquake in Haiti?
- Breakdown in law and order, with sporadic violence and looting reported.
- Money set aside for development would have to have been used for repairing damage.
- Country may also have had to borrow money, leading to national debt.
What was the immediate response to the 2010 earthquake in Haiti?
- Crucial aid was slow to arrive due to the damaged port.
- USA sent rescue teams and 10,000 troops.
- Bottled water and purification tablets were provided.
- 235,000 people were moved to less-damaged cities away from Port-au-Prince.
- The UK government donated £20 million.
- UK sent large dog search and rescue team to look for the dead.
What were the longer term impacts of the 2010 Haiti earthquake?
3-4 years after the event:
- over 170,000 people were still in displacement camps.
- 23% of children were still not in primary school.
- 70% lacked access to electricity.
- 600,000 were still ‘food insecure’.
However,
- 50% of debris had been removed.
- new building codes had been established and new houses are being built at a better quality.
- part of country’s debt had been written off.
Name a seismic event that took place in a HIC:
Earthquake in Christchurch (South Island, New Zealand) in Feb 2011.
What event preceded the seismic event in New Zealand in 2011?
Another earthquake in Sep 2010, of 7.1 MMS, hit the region of Canterbury.
Epicentre was 40 km west of Christchurch.
Describe the 2011 Christchurch earthquake:
- 6.1 MMS
- Epicentre 10km SE from centre of Christchurch
- Strong aftershocks of over 5.5 MMS
Discuss the risk and vulnerability of Christchurch, New Zealand:
- Earthquake prone as it lies on the ‘Ring of Fire’ in the Pacific.
- Christchurch, specifically, does not lie in the major earthquake zone - so most damage caused by quakes is damage to buildings.
- Epicentre was not directly in Christchurch, so risk to people was minimal as most areas, apart from the city itself, were sparsely populated.
- Residents did not see themselves as high risk:
- Stringent building regulations in place.
- Many buildings are single-storey and housing density is low.
As they are a HIC, they had more money to invest in preparation and mitigation of risk.
What were the main social impacts of the Christchurch earthquake?
- Death toll 185 - 115 were in Canterbury Television building which collapsed and caught fire.
- 7,000 injured.
- City centre was heavily destroyed and so was cordoned off for a considerable time after the earthquake, so shops and services had to relocate outside of CBD.
- 10,000 housings demolished and 100, 000 damaged.
- Couldn’t host the five Rugby World Cup matches.
What were the main economic impacts of the Christchurch earthquake?
- Habour facilities were damaged at Lyttleton - limiting imports and exports.
- Thousands of homes were damaged.
- Estimated cost of rebuild = NZ$ 40 billion.
What were the main environmental impacts of the Christchurch earthquake?
- Tasman glacier dislodged and fell into Lake Tasman causing a large tsunami over 3m high.
- Widespread soil liquefaction caused flooding in some urban areas.
What were the short-term responses to the Christchurch earthquake?
- International aid was provided (around $6-7 million).
- Aid workers from charities such as the Red Cross came to help.
- Areas were zoned to assess damage.
- 300 Australian police officers were flown in.
What were the longer-term responses to the Christchurch earthquake?
- $898 million in building insurance claims
- Water and sewerage were restored to the city by August 2011.
- Temporary housing was provided.
