mauna loa lava tube 1984

The largest volcano on earth is Mauna Loa on Hawai'i Big Island. Like all Hawaiian volcanoes, Mauna Loa was created as the Pacific tectonic plate moved over the Hawaiian hotspot in the Earth's underlying mantle. The Hawaii island volcanoes are merely the most recent evidence of this process that, over 70 million years, has created the 3,700 mi (6,000 km)-long Hawaiian–Emperor seamount chain. The prevailing, though not completely settled, view is that the hotspot has been largely stationary within the planet's mantle for much, if not all of the Cenozoic Era. However, while the Hawaiian plume is well-understood and extensively studied, the nature of hotspots themselves remains fairly enigmatic.

Position of Mauna Loa on Hawaiʻi island
Mauna Loa is among Earth's most active volcanoes, having erupted 33 times since its first well-documented historical eruption in 1843. Its most recent eruption was in 1984. Mauna Loa is certain to erupt again, and we carefully monitor the volcano for signs of unrest. See current activity and long term activity for a summary of our monitoring efforts.
Mauna Loa is a typical shield volcano in form, taking the shape of a long, broad dome extending down to the ocean floor whose slopes are about 12° at their steepest, a consequence of its extremely fluid lava. The shield-stage lavas that built the enormous main mass of the mountain are tholeiitic basalts, like those of Mauna Kea, created through the mixing of primary magma and subducted oceanic crust.

Mauna Loa is tall enough to have experienced glaciation during the last ice age, 25,000 to 15,000 years ago. Unlike Mauna Kea, on which extensive evidence of glaciation remains even today, Mauna Loa was at the time and has remained active, having grown an additional 150 to 300 m (492 to 984 ft) in height since then and covering any glacial deposits beneath new flows; strata of that age doesn't occur until at least 2,000 m (6,562 ft) down from the volcano's summit, too low for glacial growth.

Most Recent Eruption
March 24-April 15, 1984
Number of Historical Eruptions
Summit Caldera
Name: Moku`aweoweo, "Moku" refers to a coastal land section or islet; "`aweoweo" is a type of red Hawaiian fish. Literal translation is fish section (the red of the fish suggests red lava).
  • Dimension: 3 x 5 km, elongated northeast-southwest
  • Depth: 183 m deep
  • Age: estimated to have collapsed 600-750 years ago
Oldest Dated Rocks
Between 100,000 and 200,000 years ago

Estimated Age of Earliest Subaerial Eruptions
About 400,000 years ago
Estimated Age of First Eruption of Mauna Loa
Between 1,000,000 and 700,000 years before present
Hawaiian Volcano Stage
Shield-forming stage
References :  USGSwikipediaVolcano Discovery

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