Table 1. Equation of state parameters.

	MB	hyMB	Near MORB	Dry basalt (experiment)	Hydrous MORB (experiment)
ρ0 (g cm−3)	2.61±0.02	2.38±0.02	2.70±0.03	2.48	2.46, 2.09
K0 (GPa)	27±2	18±1	23±1	24±2	13.9, 6.7
	3.7±0.2	5.0±0.2	3.6±0.3	0.66±0.03	5.2, 5.7
	0.06±0.01	−0.19±0.05	0.12±0.04	−0.06±0.06

The fourth order Birch-Murnaghan fit parameters for three basaltic melts (MB, hyMB and near-MORB) at 3,000 K, compared with their experiment-based values for dry basalt (MORB) melt9, and hydrous MORB melts with 2 and 8 wt% water11.

For all three melts studied here, B(V)=28.3(±0.3)–46.1(±1.0)u+18.6(±1.3)u² (in the units of MPa/K), and γ(V)=3.2(±0.2)–3.0(±0.2)u, where u=V/V₀=ρ₀/ρ.