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Christchurch earthquake case study - Coggle Diagram
Christchurch earthquake case study
Basic facts
22nd Feb 2011, 12.51pm
Magnitude = 6.3 Richter Scale - lasted only 10 seconds but very destructive
Epicentre = 10km SE of Christchurch, 5km deep - very shallow so more shaking at surface.
Plate Boundary = Destructive boundary - Pacific Plate subducting under Australian Plate. 2011 was actually an aftershock of the 7.1 Darfield quake in Sept 2010 which had already weakened the buildings.
HIC/MEDC country
Causes
Shallow focus = 5km deep into the Earth
Occurred on a hidden fault that didn't break the surface - no one knew it was there.
Epicentre close to the city centre
Primary effects
185 dead
6500+ injured
100,000 houses damages
10,000 houses had to be demolished
50% of CBD buildings severely damaged
Liquefaction = 400,000 tonnes of silt
80% of city without electricity, water and sewage pipes ruptured
Secondary effects
Roads destroyed by liquefaction = emergency services couldn't get in.
Businesses closed for months = job losses, economy hit $40 billion/$28billion cost
1/5 of the population migrated away
Schools closed 2 weeks, kids had to share classrooms
Rugby World Cup 2011 matches cancelled = tourism loss
Mental health issues, people traumatised by 10,000+ aftershocks.
Short-term/immediate response
Search and rescue within 2 hours - UK, US Japan, Australia sent teams
Red Zone cordon - CBD closed for 2+ years
Chemical toilets for 30,000 residents as sewage broken
Army and 'Farmy Army' - 800 farmers with diggers cleared silt.
$6-7 million international aid, Red Cross appeal
Long-term responses
Land zoned: Green (can rebuild), Red (cannot rebuild, this area now parkland)
Water and sewage restored by Aug 2011
80% roads and 50% footpaths repaired by Aug 2011
$898 million paid out by Earthquake Commission (EQC)
New building code: all buildings must be base-isolated, deep foundations to bedrock, no soft storeys. Old buildings retrofitted.