Physics can be converted into mathematical formulas, making it easier for us to understand, design and make things work. Geology is partly about physics, and the Reykjanes Ridge follows a formula, as shown here:

Applying the same mathematics for the Mittelmeer-Mjösen-Zone of the European mainland, it turns out that it follows the same formula as the Reykjanes Ridge:

Comparing the grabens with the Icelandic volcanic zones shows a few things they have in common. 1. The wideness and scope of the grabens is the same as that of the convection rolls below. 2. The alignment follows the calculated lines. 3. A secondary trend to the NW is also present, to be explained with a presence of another convection rolls layer farther below. 4. The length of the grabens can be related to the size of polygons formed by the double-layer convection rolls system, such as the Rhonetal and Bresse-Graben.

Two different layers affecting the surface is a bit more difficult to comprehend than just the effect of the upper most layers on the tectonic plate with direct contact with each other. Different (or lower) layers do affect the surface. Coupling effect occurs between the asthenosphere and tectonic plate, but coupling effect can also take place between the asthenosphere and the next layer, leading to impact on the surface as well.

The grabens show more similarity with the Icelandic volcanic zones than to the Reykjanes Ridge, because of the width they cover. A jump from one convection roll to the other is found between Bresse-Graben and Oberreihn Graben. That must meen that clock-wise turning of a certain extent occurs around that point. That rotation has of course been measured and detected, for instance with the formation of dextral faults in the Oberreihn Graben area. The large scal tectonic drift affecting the brittle crust is then opposed locally by the upper most convection rolls, leading to the formation of the grabens.

The map showing the location of the Mittelmeer-Mjösen-Zone is found here: https://de.wikipedia.org/wiki/Mittelmeer-Mj%C3%B6sen-Zone

.https://en.wikipedia.org/wiki/European_Cenozoic_Rift_System