The Hawaiian Islands are Volcanoes that formed right in the middle of the Pacific plate which is moving North-westward.
Lithospheric plates lies on the weak and plastic asthenosphere. Such is the Pacific plate too. The weak asthenosphere can erupt on the surface if it gets access through faulting or other geologic conduits. When these mantle magma reaches the surface, they form hotpots on the crust.
The Hawaiian island is a series of these hotspot as it forms when mantle materials upwells to the surface. The hotspot from which the magma is sourced is relatively fixed. The moving plate is what leads to the eruption of the magma at several other parts in the crust.
