His doctoral dissertation Anisotropy and the structural evolution of the oceanic upper mantle was supervised by Frank Press.
[5] Forsyth does research on seafloor spreading at mid-ocean ridges, marine geophysics of the lithosphere and asthenosphere, and small-scale convection beneath tectonic plates.
[6] He was the leader of the MELT (Mantle Electromagnetic and Tomography) experiment, which deployed a network of seismometers on the seabed.
The MELT experiment was a pioneering effort in marine seismology and measured the structure, in terms of S wave velocities, of geologically young crust and mantle involved in seafloor spreading.
[7][9] Forsyth also led the Gravity Lineations, Intraplate Melting, Petrology and Seismology Expedition (GLIMPSE), which used shipboard gravity measurements to investigate a series of intraplate volcanic ridges in the South Pacific.