Magma generation on Mars: amounts, rates, and comparisons with Earth, moon, and venus.

Total extrusive and intrusive magma generated on Mars over the last approximately 3.8 billion years is estimated at 654 x 10(6) cubic kilometers, or 0.17 cubic kilometers per year (km(3)/yr), substantially less than rates for Earth (26 to 34 km(3)/yr) and Venus (less than 20 km(3)/yr) but much more than for the Moon (0.025 km(3)/yr). When scaled to Earth's mass the martian rate is much smaller than that for Earth or Venus and slightly smaller than for the Moon.