Table 1 Predicted maximum differential attenuation and travel time for custom MOR models using the method of Faul and Jackson (30).

Columns are as follows: (1) model conditions; (2) viscosity reduction between 0- and 10-My mantle, averaged between depths of 50 and 100 km; (3) maximum differential Embedded Image between the ridge axis and the farthest flank; (4) same as (3), but for P waves; (5) maximum differential S wave travel time between the ridge axis and the farthest flank; (6) same as (5), but for P waves.

ModelEmbedded ImageEmbedded ImageEmbedded ImageδTSδTP
Observations~1.7~0.4~2.0~0.7
Temperature only1.10.210.050.690.36
φ = 2% box (120 km)261.21.670.423.111.10
① Temp. + Embedded Image3.60.340.090.800.39
② + H2O4.60.420.110.880.41
③ + dry melt41.91.020.261.760.66
④ + hydrous melt135.21.460.372.260.78
⑤ + carbonated melt186.41.900.482.710.89