The Hawaiian archipelago is a chain of islands, atolls, and seamounts stretching across the North Pacific Ocean. The islands show a clear geological progression, becoming successively older the further they are from the southeastern end of the chain. This arrangement reflects the ongoing process of creation and raises the question of which landmass is the newest addition.
Identifying the Newest Landmass
The direct answer to the question of the youngest island is the Island of Hawaiʻi, commonly called the Big Island. This island is the only one in the chain that is currently experiencing active, long-term growth from ongoing volcanic eruptions. The Big Island is a composite of five separate shield volcanoes, with two of them, Kīlauea and Mauna Loa, being among the most active volcanoes on Earth.
Kīlauea is considered the youngest subaerial volcano on the island, having formed underwater roughly 280,000 years ago and rising above sea level around 100,000 years ago. Mauna Loa is the world’s largest active shield volcano by volume and contributes significantly to the island’s mass. The continuous output of lava from both volcanoes confirms the Island of Hawaiʻi as the youngest and still-growing landmass in the Hawaiian chain.
Understanding the Formation Process
The existence and age progression of the Hawaiian Islands are explained by the stationary mantle hotspot theory. This geological model posits that a fixed plume of hot material, a hotspot, rises from deep within the Earth’s mantle. As the plume reaches the upper mantle, it partially melts the overlying rock, producing magma that breaks through the Pacific Plate’s crust.
The Pacific Plate is not stationary; it moves slowly toward the northwest at a rate of about 4 inches per year. As the plate slides over the fixed hotspot, the magma plume punches through the plate in a new location, forming a new volcano and island. This continuous cycle creates an assembly line-like process, where newly formed islands move away from the magma source and eventually become volcanically inactive, explaining why older islands like Kauaʻi are located far to the northwest.
The Next Hawaiian Island
The next Hawaiian island is already forming beneath the ocean surface. This future landmass is the Kama‘ehuakanaloa Seamount, formerly known as Lōʻihi, located off the Big Island’s southeastern shore. This submarine volcano is the youngest in the Hawaiian-Emperor seamount chain and is currently in the preshield stage of development.
Kama‘ehuakanaloa’s summit is currently about 3,200 feet below sea level, but it is actively growing and occasionally generates earthquake swarms as it erupts underwater. Scientists estimate that the seamount will continue to build upon itself for many millennia. It is expected to finally breach the ocean surface and officially become the next Hawaiian island sometime between 10,000 and 100,000 years from now.