Subslab mantle buoyancy

The buoyancy of the mantle beneath a descending slab. Thermal, compositional or melt-related density anomalies can modify pressure and traction on the slab, potentially changing its contact with the overriding plate. It differs from the slab's own slab buoyancy. Inferring it from low seismic velocities requires independent constraints because temperature, fluids, melt and composition can produce overlapping signatures.