User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-5247339-20130622090134/@comment-3146930-20130622234732

Poseidon and Zeus have the biggest advantage against Gaea. It is the reason the Argo II only travels on the sea or in the air, as Gaea has no power in those realms. Hades has some power over the earth, but only in some ways. I mean Nico for example was able to call up black rock in The Battle of the Labyrinth, but was that rock actually Erebos, the black walls of the Underworld, or just regular black rock that made up the mountain? The first time he controlled the earth was when he killed the skeleton warriors, but it seemed more like he created a passage to the Underworld to me.

Hazel on the other hand is able to pull the riches of the Underworld to her and control almost all precious metals. The fact that she can make tunnels shows some level of control over the earth, but to what degree is unknown. Hades/Pluto is not as strong as Gaea, so even if he could control the Earth, he would only be able to delay Gaea, not overpower her.