In June last year 51 people died in a severe earthquake on the northern coast of Greece. Geophysicists are confident they know why it happened because of the insight they have now gained into the movement of the earth's crust. How far has the geophysicists' understanding of these movements and the ' engine ' that drives them progressed in recent years? John Maddox discusses this question with DR DAN MCKENZIE of Cambridge University, PROFESSOR JOHN SLATER Of MIT, and PROFESSOR KEITH RUNCORN of NeW-castle University.
Producer JANE JOHNSON