One of the two most important types of volcanoes, shield volcanoes are large and broad and have relatively gentle slopes. Kilauea on the island of Hawaii is good example of a shield volcano.
Eruptions on shield volcanoes are far less explosive than those on composite volcanoes. That is because the basalt lava that erupts from shield volcanoes contains less silica, SiO2, and is therefore less sticky (less viscous) and doesn't "plug up" the volcano. Because the lava is runnier, it travels further from the crater before it cools, causing the shield-like shape of the volcano as many eruptions build up over time.
Image: The summit of La Cumbre, a shield volcano on Fernandina Island, Galapagos Islands, as seen from Earth orbit (credit: NASA/SPL)
Lava flows from this spectacular volcano have built the island of Hawaii.
Professor Iain Stewart explains how Mount Kilauea's eruptions of lava have built up the island of Hawaii over millions of years as a magma plume known as a hotspot rises up through the Earth's crust.
Plate boundaries are places of chaos and mineral wealth.
Professor Iain Stewart explains how hotspots are a good demonstration of Earth's system of tectonic plates. As the plates move across the Earth's surface, they interact with one another at plate boundaries, which are places where earthquakes and volcanoes are common. Typically, plate boundaries are also places of great mineral wealth.
Brian Cox describes the Solar System's largest volcano.
Professor Brian Cox describes the biggest volcano in the Solar System, Olympus Mons on Mars.
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield lying on the ground. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from stratovolcanoes. This results in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form. Shield volcanoes contain low viscosity magma, which gives them flowing mafic lava.