Hazardous Earth - Case Study - Christchurch 2011 - Earthquake Impacts Flashcards
Location/ Description of the area (Christchurch)
- South Island - New Zealand - region of Canterbury
- Many regard the Christchurch earthquake in 2011
as an aftershock of the 2010 (this had an
epicentre 40km West of Christchurch and
measured at 7.1 MMS higher than in 2011 but had
fewer devastating effects. - The reason why the quake in 2011 was worse
because the ground had been weakened and the
epicentre was much closer in 2011. - Plates and types of margins: NZ is earthquake
prone as it lies on the ‘Pacific Ring of Fire’ - Pacific and Australian Plate (the plates are rubbing
horizontally past each other at the Alpine Fault -
conservative plate margin) - 20,000+ earthquakes a year - 200 felt
Magnitude, depth and location of epicentre (Christchurch)
- Magnitude:6.3 MMS
- Depth:5km (shows why so much damage - shallow
focused earthquake) - Location of epicentre: 10km SE of Christchurch - - - - As the epicentre was outside of Christchurch risk
to people was minimal as most of the area apart
from the city sparsely populated. - Vulnerability for the CBD but elsewhere there are
single storey buildings and low population density.
Aftershocks (Christchurch)
- Number of strong aftershocks
- 5.5+MMS further damaged buildings in the centre
and suburbs.
Primary Social Impacts (Christchurch)
-80% city without electricity
-Death toll was 185 - 115 inside Canterbury
Television Building which collapsed and caught
fire
-7,000 people treated for injuries
-Spire of Christchurch cathedral brought down
Primary economic impacts (Christchurch)
-50% of City centre destroyed
-1,000 building collapsed or demolished afterwards
because they were deemed dangerous
Secondary social Impacts (Christchurch)
-10,000 houses in suburbs demolished - 100,000
dwellings damaged
-People affected mentally by the earthquake - 80%
in a survey said their life had changed
considerably
-School had to share classrooms because of
damage to other buildings
Secondary economic impacts (Christchurch)
-City centre was cordoned off for some time so
shops and other services had to relocated outside
CBD
-Harbour facilities at Lyttelton damaged
-Christchurch could no longer host Rugby world
cup matches so lost benefits that tourism would
have brought in
-Some economists have estimated it will take NZ
economy 50-100 years to recover
Secondary environmental impacts (Christchurch)
- Tasman Glacier 200km from Epicentre - ice
dislodged fell into lake Tasman causing tsunami
3m+ - Soil liquefaction (40,000 tones of silt) - areas
affected couldn’t be rebuild after - Water released during liquefaction leading to
flooding - Some died as a result of cliff fall
- Damage to roads from liquefaction made it
difficult for people and emergency services to
move around.
Secondary political impacts (Christchurch)
- NZ Govt rebuild cost NZ$40 billion
- Population that had been increasing for decades
declined after the shake.
Short term responses (Christchurch)
- Rescue crews from Japan, US, UK
- Australian donating $5million
- Government declared state of emergency until
April 2011 - Domestic help - Farmy Army made up of 800
farmers brought their farm machines to help
clean up city - Chemical toilets provided for 30,000 residents
- Sewages systems so damaged emergency latrines
were set up
Long term responses (Christchurch)
- Divided into 4 zones:
- Green Zone - land undamaged and could be
rebuilt - Orange Zone - checks needed before rebuilding
- White Zone - area not yet checked
- Red Zone - unstable
- Green Zone - land undamaged and could be
- Government provided temp housing
- Water and sewage restored by August
- Road and house cleared of silt from liquefaction
by August 80% of roads and 50% footpaths
repaired
