Magma

How much magma is in the earths core. If you could express it in cubic miles it will give me a good idea.

For how long i am not sure but the earth has spewed out lava creating mountains ect. How long can this continue, it seems odd to me that it has not dried up long ago. Can the magma replenish its self, or will it run out in the future.

here is a quick link for someone's numbers;

www.madsci.org...

"The mantle extends from the base of the crust to a depth of about 2900 km (1800 mi). Except for the zone known as the asthenosphere, it is solid, and its density, increasing with depth, ranges from 3.3 to 6 g/cm3. The upper mantle is composed of iron and magnesium silicates. The lower part may consist of a mixture of oxides of magnesium, silicon, and iron.This layer is made up of mostly 11 elements : oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium, titanium, hydrogen, and phosphorous. These 11 elements are all mixed up within different compounds in a crystal form, so that we can call them minerals. For this layer we calculate a value of:

volume = 9.199 x10^20 cubic meters
density ranges from 3.3 g/cm3 (upper mantle) to
6.0 g/cm3 (lower mantle)
mass = 4.278 x10^24 kg = 68.4 % of earth's mass
= 49.5 % of earth's volume"


Magma replenishes itself through subduction, and others in the rock cycle