Earthquakes Case Study: Christchurch New Zealand, 2011

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National 5 Geography

Global Issues- Environmental Hazards- Case Study

Earthquake: Christchurch, New Zealand 2011

Cause

The earthquake occurred on 22nd February 2011 at 12.51pm (local time)

Epicentre: 10km south east of Christchurch

Focus: 5km down

Magnitude: 6.3 on the Richter Scale

New Zealand lies above the boundary of two tectonic plates, on the Pacific Ring of Fire. The oceanic Pacific plate and the continental Australian plate move towards each other, causing the heavier oceanic plate to be pulled beneath the Australian plate in a process known as subduction. This creates friction, preventing the plates from moving. Eventually, the build up of pressure is too great and the oceanic plate is pushed downwards, creating an earthquake.

It is thought that the earthquake was triggered by a magnitude 7.0 (on the Richter Scale) earthquake that occurred in September 2010. This earthquake caused far less damage and there were no fatalities, despite it being more powerful than the February quake. The earthquake in September happened during the night (most people were at home, asleep), but the February earthquake occurred during lunchtime(when people were out and about). It is also thought that much of the damage caused by the February earthquake was due to the fact that several buildings had already been weakened or damaged by the earthquake the previous September. In addition, the epicentre of the earthquake in February was significantly closer to the city of Christchurch, and the focus was not as far beneath the Earth's surface. The ground acceleration (how much and how fast the ground moves) was very high in the February earthquake, causing severe damage.

Impact

People

185 people died

164 people were seriously injured, with thousands more injured

70,000 people were forced to leave the city due to uninhabitable homes, lack of basic services and continuing aftershocks

People had to use portable or chemical toilets and get their water from tankers for months due to badly damaged water and sewage pipes

Communications were cut off as power lines were damaged

People lost their homes as they collapsed

The population of Christchurch decreased as many people were displaced by the earthquake and never returned

Landscape

Approximately 100,000 buildings were damaged

10,000 buildings had to be demolished due to extensive damage

Roads and bridges were badly damaged, preventing rescue workers from gaining access

The earthquake resulted in a significant amount of liquefaction (underground water in the soil comes to the surface). Thick muddy slush, composed of water and sewage from ruptured pipes, spread through parts of the city, causing buildings to sink into the ground. Roads, homes and schools flooded with silt.

Management

Prediction

Despite earthquakes being very difficult to predict, experts know which areas of the world are most at risk

Frequency patterns from previous earthquakes can help to predict when the next one will occur

Active earthquake zones are closely monitored for seismic activity through the use of seismometers, seismographs and tiltmeters

Earth tremors are detected using sophisticated sound recording equipment

Planning

Earthquake drills are practised in schools

National earthquake drills (New Zealand Shake Out)

Information about what to do in the event of an earthquake is readily available

Earthquake proof buildings have been constructed to sway with the motion of the ground

Emergency services are better prepared, with improved training and equipment, including heat seeking equipment and sniffer dogs

In some countries, text messages are sent to people to alert them of an imminent earthquake and to give advice about getting help

Short Term Aid

National State of Emergency declared

New Zealand, Britain, USA China, Japan, Taiwan, Mexico and Australia all contributed to a rescue team of over 600 rescuers

Blankets and tents were provided the day after the earthquake, ensuring that those who had lost their homes were not at risk of hypothermia

Bottled water was also provided as water supplies were cut off

An evacuation centre for 2,000 people was opened, within a day of the earthquake

The British Red Cross made an initial donation of £50,000

A Japanese team of specialists from the coastguard, fire and police service responded with aftershock warning devices, gas detectors, tents, portable toilets and food

Doctors, nurses, medical equipment and a field hospital were contributed to by Japan and Australia

Electricity was restored to 75% of the city within three days

Long Term Aid

Workers were brought in from other countries to help with the reconstruction of Christchurch

Almost $900 million in buildings claims was paid out

The Red Cross provided grants to families with children under 5 who were living in severely damaged houses

Ordinary people and the government offered temporary housing

Groups of ordinary people from all over New Zealand came to Christchurch to help to restore the city and clean up the silt

Water and sewage systems were restored

Roads and bridges were rebuilt

However, repairs were slow due to road damage and some parts of Christchurch are still in disrepair due to the effects of the earthquake