Photograph by D. Little (date unknown). View of the NNW flank of Mauna Loa Volcano from the south side of Mauna Kea Volcano, Hawai`i; both are shield volcanoes.

Shield volcano

Volcanoes with broad, gentle slopes and built by the eruption of fluid basalt lava are called shield volcanoes. Basalt lava tends to build enormous, low-angle cones because it flows across the ground easily and can form lava tubes that enable lava to flow tens of kilometers from an erupting vent with very little cooling. The largest volcanoes on Earth are shield volcanoes. The name comes from a perceived resemblance to the shape of a warrior's shield.

Related photo glossary terms

• Lava tubes
• Rift zones
• Basaltic lava flows: `a`a and pahoehoe

Did you know?

• Mauna Loa volcano on the Island of Hawai`i is the largest volcano on Earth. With an elevation of 4,170 m above sea level, its long submarine flanks descend to the sea floor an additional 5 km, and the sea floor in turn is depressed by Mauna Loa's great mass another 8 km. This makes the volcano's summit about 17 km (56,000 ft) above its base! The volcano is constructed of an estimated 80,000 km<sup>3</sup> of basalt! For more information about Mauna Loa, see the USGS Hawaiian Volcano Observatory website.
• Of the 1,511 volcanoes known to have erupted in the past 10,000 years, 164 are shield volcanoes.
• The largest volcano in the Cascades, Medicine Lake Volcano in northern California, is a shield volcano.
• Lava tubes are essential for building broad shield volcanoes, because they permit lava to travel great distances from an erupting vent. For example, geologists estimate that as much as 58 percent of Kilauea volcano is covered with lava fed from lava tubes.
• Shield volcanoes generate some of Earth's largest landslides. A landslide from East Moloka`i Volcano on Moloka`i Island had a volume of about 500 km³ and slid at least 120 km across the ocean floor.
• One of the largest known volcanoes in our solar system, Olympus Mons on Mars, is a shield volcano.