What is the magma ocean of Io?

There is a good news article in Astronomy Now Online on this very subject. It apparently is between 30-50 kilometers beneath the satellite's crust and makes up and estimated 10% of its mantle by volume. You can read more details about it at a href="http://www.astronomynow.com/news/n1105/13Io/" rel="nofollow"http://www.astronomynow.com/news/n1105/1…/a