11. The lithosphere is only 30 km and there is a low seismic velocity asthenosphere below. 12. As delamination continues, more asthenosphere rises to replace the lower lithosphere as it sinks. 13. A steepening of the subduction after 12 mya resulted in the influx of hot asthenosphere . 14. Beneath the northern margin of the plateau, anomalies in the asthenosphere have been described. 15. The weakness of the asthenosphere allows the tectonic plates to move easily towards a subduction zone. 16. The geothermal structure in a subduction zone determines the melting rate of subduction slab and asthenosphere . 17. Several explanations have been proposed : a lower limit to the pliable asthenosphere , a phase transition, 18. This would suggest that the Lithosphere-Asthenosphere boundary underneath oceanic lithosphere also deepens with plate age. 19. The lithosphere essentially " floats " on the asthenosphere and is broken-up into ten major plates. 20. The calculated source depth of the lava is consistent with an origin at this depth in the asthenosphere .
