The Yellowstone area can be studied with a simple formula:
Many volcanic sites in Iceland can be calculated in the same way. For instance Hekla is aligned according the same formula as shown below.
In exactly the same way, the alignment of Hekla can be calculated, and its counterpart 30° farther to the east also! Without the knowledge of the forces underneath no one would see the resemblance.
All those places are aligned at an angle exactly between the direction of convection rolls and EW-axis. Yellowstone is in the middle of a diamond-shaped polygon, providing the basic framework for the surface tectonics.