Building Collapse

One of the main hazards posed by an earthquake is that of building collapse. This is the primary cause of death from an earthquake, whether it be from the building your in (or walking by) falling on you or from falling objects inside. Damaged buildings remain a hazard even after the earthquake has ceased and so roads (infrastructure) are disrupted. There are a number of forms of building collapse and many can be avoided if building standards (of the correct level) are adhered to.

Basic Collapse

This is commonly caused by poor building standards and is frequently seen in hotter countries. Such buildings are built with weak walls and heavy ceilings. The joints between the ceiling and the wall may be so weak that the ceiling simply falls in, killing all on that floor. The picture on the left shows a building that had such weak walls that they broke under the weight of the ceilings and caused the collapse of two floors. You can see that the horizontal structures appear almost intact here. There is no sign of the vertical walls which should have been supporting them. Such a collapse can be easily avoided with the use of strong metal superstructure. However builders often try to avoid installing such expensive and heavy supports. Sometimes they even use hollow tubes filled with concrete, of course this will normally fail under stress.

Returning to the issue of concrete ceilings. It is also likely that a large concrete slab will simply snap. When this happens it will fall into any room directly below. The photo on the right shows this type of collapse. Although the chance of surviving a diagonal collapse is greater than a flat one, you are unlikely to survive. The picture clearly demonstrates the tendency to use large flat concrete roofs. In the UK and USA such roofs are uncommon, often replaced by sloping roofs. This helps to show how simple improvements in the building regulations can save lives.

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2: Foundation Failure
3: Pancake Collapse
4: Conclusions

By Paul Wittle