A University of Hawaii geophysicist may have helped make that answer much clearer.
Cicily Wolfe led the study, which captured the best images yet of a plume hot rock that rises from earth's deep mantle and fuels the volcanoes of the islands.
It reveals the structure plume down to at least 900 miles. The $4.5-million experiment measured the velocity of earthquake waves using ocean-bottom sensors around Hawaii.
Wolfe's team found that as the plume rises, it gets squashed into a pancake shape at 320 miles beneath the earth's crust.
"This is the process that generates the entire state of Hawaii and anyone coming to the islands must wonder, gee, isn't it curious that there are these islands in the middle of the Pacific away from a plate boundary, how did this happen?" Wolfe said. "These images are a snapshot of what's going on today, deep in the earth."
Wolfe says the islands are being pushed towards Japan, by about a few centimeters each day.