Lessons from the Christchurch Earthquake

Predicting the Danger and Risks

This 8.5 minute documentary that went to air in New Zealand in 1996 warned of the dangers that Christchurch faced from a major earthquake. This clip below shows that building and infrastructure problems were then well known. In the earthquakes that took place on September 4 2010 and February 22 2011, many of the buildings shown in the clip were badly damaged or collapsed, including a number of buildings claimed to be success stories.

How Did Christchurch’s Buildings and Infrastructure Perform?

A few days ago, the Institution of Professional Engineers of New Zealand released a fact sheet about the background into building codes in New Zealand and how effectively buildings and infrastructure constructed in different times performed. This document can be viewed here. Particularly interesting is that the Institution notes:

Many buildings designed before the early 1980s may have experienced earthquake loads significantly above that for which they were designed. Nevertheless, many of them have experienced no or minimal damage.

The last major update to the design standards for earthquake loadings was in the early 1980s, which makes the complete collapse of the CTV Building constructed in 1986 and the stairwell failure of the Forsyth Barr Building while many older buildings survived somewhat puzzling. This is currently the subject of an inquiry under way in New Zealand. Also noted was that the majority of the damage to underground infrastructure was the result of liquefaction in Christchurch’s saturated, loose soils.

What About Earthquakes in Australia?

There’s also recently been some comments about the likelihood of such a large quake causing damage in Australia’s cities. While Australia has a far lower risk of damage from major earthquakes due to its location away from tectonic plate boundaries and major fault lines, some cities are still at risk from moderate sized earthquakes measuring between 5 and 6 in magnitude close to urban areas. Both of the cities of Adelaide and Newcastle have been damaged by earthquakes in 1954 and 1989 respectively, with the latter resulting in a number of fatalities. These, however, are still very small in scale in terms of energy released compared to earthquakes that can occur close to the major fault lines.

As individuals, there are some things that can be done to protect yourself during an earthquake. In the US, the recommended course of action is a quick three step procedure called “Drop, Cover and Hold On”. This involves dropping onto your hands and knees, covering yourself under a table or protecting your head with your arms and holding on to your shelter until the shaking stops. The aim of this is to prevent injury from flying and falling debris.

Media often portrays the wrong ways of reacting to an earthquake. While some buildings do collapse during major earthquakes, the majority escape with minimal or no damage. If a building does collapse, your shelter can provide a void. The natural instinct to run outside puts you at risk of injury from falling debris, while other recommendations such as standing in the doorway do not offer much protection.

Source:

Earthquake Country Alliance

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