Corrections to Nature 387, 169-173 (1997)
  1. Figure 3: center right and bottom right panel x-axis labels should have exponents 5 and 6, instead of 4 and 5.
  2. Figure 3 caption line 7 should be "Viscosity is 6*10**21 Pas", i.e. a factor 6 is missing.
  3. At the end of Figure 3 caption "or viscous rheology (fourth row)" should be added.