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IN A typical year our planet suffers 18 major earthquakes and one great quake measuring 8 or higher on the Richter scale. Predicting when or where the next one will happen remains impossible, but by now you’d think we would at least have a clear-cut system for identifying the faults that cause them. Not so. A blistering row over whether a convention centre in Salt Lake City, built for this year’s winter Olympics, is or isn’t straddling an active fault reveals just how uncertain is our knowledge of the ground beneath our feet (see “Olympic palace on shaky ground?”).…