If the ages of the islands are plotted against their distance from the currently erupting volcano on the Big Island of Hawaii, the following graph results:
This graph supports the hypothesis that the Hawaiian archipelago formed as the Pacific Plate moved at a relatively constant rate over a hotspot that is currently located under the Big Island. As the plate moved to the northwest, islands moved away from the hotspot and began to erode and subside while new islands were created over the hotspot.
This graph also can be used to calculate the rate at which the Pacific Plate is moving. Necker Island is now about 1,050 kilometers (650 miles) from the Big Island, so the Pacific Plate must have moved that distance over the past 10.3 million years. This rate of movement is equivalent to about 10 centimeters (4 inches) per year.