What is the largest volcano on Earth?
Mauna Loa in Hawaii is the largest active volcano on Earth by volume. Measured from its base on the seafloor, it rises about 9 kilometers, taller than Mount Everest.
Mauna Loa is a shield volcano, built by thousands of flows of runny lava that spread out to form broad, gentle slopes. Its summit is about 4,170 meters above sea level, but most of the volcano lies under the ocean, and its weight presses the seafloor down even further. It covers about half of the Big Island of Hawaii.
Mauna Loa has erupted more than 30 times since 1843. Its most recent eruption, in late 2022, was its first in 38 years and drew crowds to watch lava flows. Its neighbor, Mauna Kea, is the tallest mountain on Earth measured from base to peak.
Even bigger volcanoes
Underwater, some extinct volcanoes are even larger. Tamu Massif, in the Pacific Ocean east of Japan, is a huge underwater volcanic feature, and Pūhāhonu, in the Hawaiian chain, was identified in 2020 as the largest known shield volcano. In the solar system, Olympus Mons on Mars is far bigger.
Did You Know?
Mauna Loa means long mountain in Hawaiian, describing its broad, gently sloping shape.