Spewing lava and gas from deep within the earth, volcanoes are one of nature’s most explosive natural features. Thousands of volcanoes dot the planet but only about 1,500 are considered active, meaning they have erupted at some point in the last 10,000 years. The largest of these active volcanoes in both mass and volume is Mauna Loa on the island of Hawaii, the largest island of the Hawaiian archipelago.
Scientists debate over when the first inhabitants of the Hawaiian Islands arrived, proposing anytime between 124 and 1219 A.D. Isolated for at least 500 years, the native Hawaiians first came into contact with Europeans on January 18, 1778 when Captain James Cook, a British explorer and captain, discovered the islands on his third voyage to the Pacific Ocean. Cook named the newly discovered land the “Sandwich Islands” after John Montagu, the fourth Earl of Sandwich and head of the Royal Navy. After further exploration of the northern reaches of the Pacific Ocean, Cook returned to the islands in 1779. This second visit was the first recorded time an attempt was made to reach the summit of Mauna Loa. John Ledyard, a member of Cook’s expedition, and several of his shipmates attempted a direct route up the mountain but were unsuccessful and were forced to turn back due to the difficulty of the terrain. The map below, made by Rigobert Bonne in Paris only a few years after the discovery of the islands in 1785, depicts the volcano as “Mowna Roa” as well as the path of Cook’s explorations.
In the next several decades, various European explorers landed in Hawaii. Archibald Menzies, a Scottish botanist and naturalist, on the 1793 Vancouver Expedition, attempted to reach the summit of Mauna Loa three times. On the third attempt, after seeking advice from the Hawaiian leaders, King Kamehameha I, and by using the ‘Ainapo Trail, Menzies and several companions were successful in being the first Europeans to reach the top of the volcano. Fifty years later in 1841, the United States Exploring Expedition of 1838-42, also known as the Wilkes Expedition, performed the first systematic volcano and geologic research in the Hawaiian Islands led by geologist James D. Dana. After the four year expedition, nineteen volumes were published by Wilkes detailing the information acquired from the voyage including two volumes of maps. The map below is from one of these volumes and is one of the earliest detailed maps of Mauna Loa and the nearby peak, Mauna Kea.
Over the following centuries, Mauna Loa has been closely monitored due to high activity and its proximity to population centers. Erupting for the last 700,000 years, Mauna Loa is one of the most active volcanoes in the world with the first recorded eruption occurring in 1843 and its most recent in 1984. By zooming in to the geologic map below, made in 1930 by the U.S. Geological Survey, you can see the various layers left through the years by the eruptions of both Mauna Loa and the nearby volcano of Kilauea.
Mauna Loa is one of five above ground volcanoes that make up the island of Hawaii but with the largest mass in the world, it makes up more than half of the surface area of the island. The volcano covers a land area of 2,035 square miles (5,271 km2) and spans a width of 75 miles (120 km). Most of the massive structure of the volcano is hidden deep underwater. If measured from the base at the bottom of the ocean floor, the crust of which is depressed due to the weight of the mountain, to the top peak, Mauna Loa’s total height is 56,000 feet (17,170 m), nearly twice the height of Mount Everest from sea level!
In 1912, the Hawaiian Volcano Observatory was created and built on the rim of Kilauea Caldera, run by the prominent geologist Thomas Jaggar. In 1924, the observatory was taken over by the United States Geological Survey, who still run it today as one of the leading institutions on the study of volcanoes. On August 1, 1916, Hawaii Volcanoes National Park was established, encompassing the summit and southeastern side of Mauna Loa and Kilauea. The park can be seen on the 2012 map below including the closed areas due to recent eruptions from Kilauea.
While Mauna Loa is the largest active volcano, there is one other massive mountain that deserves a mention. In 2013, though extinct, scientists discovered an underwater volcano in a remote section of the Pacific Ocean that is now recognized as the largest volcano on earth named Tamu Massif. This immense volcano is about the size of New Mexico! But as the largest volcano that can be seen and as one of the most active, Mauna Loa continues to fascinate scientists and onlookers alike.
- Check out this interactive time-lapse animation of volcanic eruptions and earthquakes since 1960 made by the Smithsonian Global Volcanism Program!
- Read more of our posts from the Extremities of the Earth series!
- View photographs of volcanoes in Hawaii from the Prints and Photographs Division.
- Take a look at the entire Volume 2 of Charles Wilkes atlas detailing his expedition.