Post-shield volcanism began 100,000 years ago and covered the entire surface of the volcano. The most recent Hualalai eruptions occurred in 1800-1801. Hualalai, the third of Hawaii's active shield volcanoes, is located northwest and west of its giant neighbors Mauna Loa and Mauna Kea. Hualalai volcano last erupted between 1800-1801, when it produced lava flows from 5 fissure vents that reached the sea and buried Hawaiian villages. The Hualalai began to erupt about 800,000 years ago and broke the surface of the sea about 300,000 years ago.
The volcano has 3 rift zones, the most prominent being the northwest rift, which is about 40 km long and continues in the sea to a depth of 3000 m. Approximately 40 to 70 million years ago, Hawaii's 137 islands began to form. Each island in the archipelago originated from multiple underwater volcanic eruptions. While it is true that volcanoes played an important role in the formation of this chain of islands, there is much more to the history of the Hawaiian Islands.
Volcanoes can also form in the middle of a plate, where magma rises upwards until it erupts on the seabed, in what is called a “hot spot”. Most of the world's active volcanoes are found in the Ring of Fire and on the boundaries of the Pacific tectonic plate. Due to their volcanic origins, it is not surprising that all the islands in this chain have at least one volcano. Mauna Kea, a dormant volcano on the Big Island, is in fact the tallest mountain in the world, measured from its base to its top.