The grid of convection rolls explains the tectonic framework of Iceland:
The same applies for main volcanic and geothermal sites:
The tectonic framework shows direct resemblance with the model of convection rolls found under the country. Likewise, many volcanic and geothermal sites are found in context with the crossings of division lines of different layers of mantle convection rolls.
Besides this, we can look into the polygons of the network of division lines between convection rolls of different layers:
The calderas along the central parts of Iceland have the function of providing magma for dikes to fill up the void created by tectonic drift.