The Hawaiian Islands are different from most volcanic activity explained by plate tectonics. Most of the world's volcanic activity is located at the edges of the major tectonic plates. It results from plates either pulling apart, converging together, or sliding past one another. But the Hawaiian Islands are located well within the pacific plate interior, thousands of miles from the edge of the plate. Geologists have developed the hot spot theory to explain the existence of Hawaii and similar volcanic island chains. The tectonic plates exist in the lithosphere on the Earth's surface but some parts of the Earth have hot spots, or fixed, concentrated pockets of extreme heat that traverse the asthenosphere and melt the crust at the surface and push magma to the surface through volcanoes. As the surface plate moves over the hot spot, the volcanic activity travels across the plate slowly in a relatively linear fashion. That is why the Hawaiian Islands form a relatively linear chain of major islands with the oldest island (Kuaii) on the western end and the currently forming island (Hawaii, aka the Big Island, with the active volcano) on the eastern end. So the Hawaiian Islands do make a case for plate tectonics but only when coupled with the hot spot theory.