According to a web search an Earth Anchor is a rod, typically 2-3 ft long, with an auger bit. Screwed into the ground they require a pull of around 1500lb. Multiple anchors might be better than a single larger one.
I wonder if it is better to load them along the rod's length, as though you were trying to pull it out of the ground, or to pull from the side, as though it were a tent peg.
paulj