New Information on the formation of volcanic islands

What causes the fluctuations that turn mantle-plume volcanic activity on and off, as described in this article about how the previous theory/assumption of single-burst volcanic island formation is now being revised?

What kind of energy and/or gravitational fluctuations could cause an island-forming convection current to taper off and later resume to earlier levels of intensity?

https://www.sciencealert.com/the-world-s-largest-volcano-isn-t-what-we-thought-it-was