Answer:
The current eruption of Mauna Loa on the Big Island of Hawaii is part of a long history of volcanic activity that formed the Hawaiian chain and is a vivid demonstration that the giant plates of the Earth's crust move over time.
If you look at a map of the Hawaiian islands, you will see they form a chain that runs in a northwesterly direction, with Big Island at the southern end of the chain. It is also the only island in the group that is volcanically active.
This chain of islands in the middle of the Pacific Ocean came to the attention of Canadian geologist John Tuzo Wilson who, in 1963, proposed the idea that the islands were created by a very long lasting and extremely hot spot in the Earth's mantle. His idea was that a plume of molten magma that rises up from deep within the Earth and had punched a hole through the overlying crust.
As the hot lava flows upwards over thousands of years, it builds up into a volcanic mountain that eventually pokes through the ocean surface, forming an island.
This process continues today with the recent eruptions on the summit of Mauna Loa, and with ongoing eruptions on Kilauea, located on the other side of Big Island. In other words, Big Island is getting bigger.
But Wilson saw something more than just the hot spot punching holes in the crust. He saw the Hawaiian island chain as the result of a series of holes based on the fact that rocks on the other islands become progressively older as you go north. Those on Kauai, the northernmost inhabited island, are about five-and-a-half million years old, while those on Big Island are less than one million years old.