One week on from the destruction of Manhattan's twin towers, the initial shock has given way to a desperate need to believe that there are lessons to be learnt.With the image of the collapsing towers fresh in the collective consciousness, there are the inevitable mutterings that countries which build too high put their citizens at risk.
Turning our back on tall buildings would be as absurd as, say, halting investment in public transport when terrorists released poisonous gas into Tokyo's underground system.
Architects and engineers have to consider every imaginable disaster. The twin towers themselves were built to withstand earthquakes, hurricane-force winds, and even - to a large extent - terrorist attack. Being hit by two jetliners travelling at full speed was not imaginable - before last week, it seemed about as likely as the possibility of New York being swamped by a Noah's arkstyle flood, where only those in tall buildings could survive. The point about a catastrophe - as opposed to an emergency - is that it takes everybody by surprise. It is impossible to predict where or how we will be most vulnerable when disaster strikes again.
With time, thought and a reasonable idea of the likely threat - architecture has an astonishing capacity to mitigate the impact of disaster. This week's technical section looks at the way buildings can be designed to withstand earthquakes. The potential to save lives is enormous. More than 30,000 lives were lost in the earthquake which shook the Gujarat region of India on 26 January this year. Many of the deaths could have been avoided if regional buildings had been constructed in a different way. Fewer than 60 people died in the comparable Northridge earthquake which struck Los Angeles in 1994.
It is important to focus on disasters which we know will strike again, and to look at ways of increasing safety without specific knowledge of the threat. Previous research produced ATC-20, a system for making on-thespot decisions as to the structural integrity of earthquake-damaged structures. It is currently being used to assess whether buildings in the vicinity of the World Trade Center are safe to use.