The hotspot has existed for at least 80 million years, and the Emperor Seamounts chain of old volcanoes stretches almost 5,800 km (3,600 miles) away from the hotspot. The upwelling of the hot magma creates volcanoes, and each individual volcano erupts for a few million years before the movement of the plate carries it away from the rising magma. The hotspot remains in a fixed position, while the Pacific Plate drifts over it at a rate of about 10 cm per year. Like all of the Hawaiian islands, Mauna Loa has its origins in a hotspot-a plume of magma rising from deep in the Earth's mantle. Mauna Loa probably began erupting between 700,000 and one million years ago, and has grown steadily since then. Hawaii Volcanoes National Park covers the summit and the south-eastern flank of the volcano, including a separate volcano, Kilauea. Observations of the atmosphere are undertaken at the Mauna Loa Observatory, and of the Sun at the Mauna Loa Solar Observatory, both located near its summit. Mauna Loa has been intensively monitored by the Hawaiian Volcano Observatory (HVO) since 1912. In view of the hazards it poses to population centers, Mauna Loa is part of the Decade Volcanoes program, which encourages studies of the most dangerous volcanoes. No recent eruptions of the volcano have caused fatalities, but eruptions in 19 destroyed villages, and the city of Hilo is partly built on lava flows from the late 19th century. Mauna Loa's most recent eruption occurred in 1984. The slow drift of the Pacific Plate will eventually carry the volcano away from the hotspot, and the volcano will thus become extinct within 500,000 to one million years from now. Its magma comes from a hotspot in the Earth's mantle far beneath the island that has been responsible for the creation of the Hawaiian island chain for tens of million of years. The volcano has probably been erupting for at least 700,000 years and may have emerged from the sea about 400,000 years ago, although the oldest known dated rocks do not extend beyond 200,000 years. Lava erupted from Mauna Loa is very fluid, and the volcano has extremely shallow slopes as a result. In Hawaiian, mauna loa means "long mountain". It is Earth's largest mountain, with a volume estimated at approximately 18,000 cubic miles (75,000 km³), although its peak is about 36 m (120 ft) lower than that of its neighbour, Mauna Kea. Mauna Loa is an active shield volcano in the Hawaiian Islands, one of five volcanoes that form the Island of Hawaii. Related subjects: Geology and geophysics North American Geography Mauna Loa
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