This sounds more like geology (or planetary studies) than astronomy.
Presumably the direction of plate motion changed where there is a bend in the chain. So..
Divide 4000*10^3 m by 0.08 m/year.
You get 50 million years.
From Hawaii to the bend in the Hawaiian-Emperor chain is about 4000 km. If the Pacific plate is moving 8.0 cm a year, estimate how long ago the direction of plate motion changed. (The San Andreas Fault in southern California became active at about the same time!)
Does anyone have an answer?
2 answers
Thank you!