Mauna Kea
Mauna Kea ( or , ) is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii. Most of the mountain is under water, and when measured from its oceanic base, Mauna Kea is the tallest mountain in the world measuring over . Mauna Kea is about a million years old, and has thus passed the most active shield stage of life hundreds of thousands of years ago. In its current post-shield state, its lava is more viscous, resulting in a steeper profile. Late volcanism has also given it a much rougher appearance than its neighboring volcanoes due to construction of cinder cones, decentralization of its rift zones, glaciation on its peak, and weathering by the prevailing trade winds. Mauna Kea last erupted 6,000 to 4,000 years ago and is now considered dormant. The peak is only about higher than its more massive neighbor, Mauna Loa.
Evolution of Hawaiian volcanoes
The Hawaiian-Emperor seamount chain is remarkable for its length and its number of volcanoes. The chain is split into two subsections across a break, separating the older Emperor Seamount Chain from the younger Hawaiian Ridge; the "V" shape bend of the chain is easily noticeable on maps. The volcanoes are progressively younger to the southeast; the oldest dated volcano, located at the northern end, is 81 million years old. The break between the two sub-chains is 43 million years; in comparison, the oldest of the principal islands, Kauai, is little more than 5 million years.