Bob Holmes The earthquake that turned many of Kobe's buildings to rubble last week should not topple Japan's building codes, which are stricter even than California's, say American earthquake engineers. Many of the buildings that collapsed probably followed an outmoded Japanese design strategy from the 1950s and 196Os.
Engineers design modern office buildings, bridges and over-passes with preplanned weak spots.
During a severe earthquake, these weak spots break or buckle, absorbing some of the energy of the shaking and reducing the chance that the whole structure will collapse. Until the late 196Os, Japanese engineers designed buildings to be more rigid than their counterparts in California, says Andrei Reinhorn of the National Centre for Earthquake Engineering Research, based at the State University of New York at Buffalo. This made the buildings more likely to ride out moderate earthquakes without damage, but left them vulnerable to collapse in more severe quakes. Early indications from Kobe are that most of the buildings that failed were put up at least 25 years ago, when those standards were in force. More modern Japanese regulations call for buildings to be made strong enough to resist damage in moderate quakes and also to incorporate failure points that break in severe quakes to prevent total collapse.