Pressure (a) and temperature (b) models for the Tohoku-oki megathrust. The green line represents the lithostatic pressure σV, and the light blue line shows the hydrostatic pressure gradient. The pore pressure ratio λ is indicated by dotted lines. The thick blue line represents the pore pressure model. Pp at the depth z = 21.5 to 45 km is given by Pp = σV((1 - β)λc + β) and β = (z - zup)/(zdown-zup), where λc = 0.53, zdown = 45 km, and zup = 21.5 km.