By Wendy Barnaby
Engineers can protect buildings against earthquakes, but it's expensive. "We can design new buildings to be almost earthquake-proof," said Dr Adam Crewe at the Festival of Science in Exeter on Monday. For new buildings it's quite easy. Techniques can include designing in a point which will mop up the quake's energy and fail (leaving the building intact), and which can be replaced afterwards. More expensively, a building can be isolated altogether from the movement of the ground beneath it.
But are we prepared to pay? "We could be talking about 20 or 30% on the cost of new buildings in the UK. You're asking the people to protect a building from an earthquake that may not occur: the biggest one we could think of that might happen once in every 10,000 years," said Crewe.
Helped by his audience, Adam Crewe shook model buildings and popped balloons of different sizes to show the power of various earthquakes. A lecturer in civil engineering at the University of Bristol, he was delivering his BA Isambard Kingdom Brunel Award Lecture.
The UK is by no means free of earthquakes. There were four here last month; none big enough to leave destruction in its wake. Only 11 people have died in earthquakes in the UK since 1580 - and one of those was a woman who thought the end of the world had come, and perished jumping out a window.
With the most severe UK quake measuring 5.1 on the Richter scale, all this country's are tiddlers compared with the most powerful earthquake ever, which was in Chile, in 1960. It measured 9.5 but, because it struck in a remote place, caused fewer than 5000 deaths.
Although most people would prefer to be in a low building rather than a tall one in an earthquake, the wisdom of their choice is determined by the type of quake. Damage will depend on the frequency at which the building naturally sways from side to side, the way it sways, and how the energy of the movement is damped down by various engineering techniques.
While these can protect new buildings so that quakes will not cause unacceptable damage, it's the current stock of buildings that need better protection. Engineers can supply materials for these too, but again, the problem is the cost. "In countries like Iran, Iraq and Turkey where most people die from earthquakes, the houses need cheap materials," said Adam Crewe. "The challenge for earthquake engineering is to come up with techniques that are cheap and appropriate for particular countries. We're still working on it," he said.