Mauna Loa volcano is one of five volcanoes that form the Island of Hawaii in the Pacific Ocean. Mauna Loa has is the world's largest subaerial, its most active giant shield volcano.
Location: 19.475 N 155.608 W.
Elevation above sea level: 4,170 m.
Area: 5,271 km2 (50.5% of Hawaii island)
Volume: 80,000 km3.
Map of Mauna Loa Volcano on Hawaii Island
Mauna Loa Volcano Summit Caldera
Mauna Loa volcano has eruptions from:
- The summit, occupied by a large caldera;
- The NE and SW rift zones on the flanks.
When Mauna Loa volcano erupts, its eruptions are usually huge and produce large rivers of lava. Mauna Loa's lava is very fluid, silica-poor and so to be non-explosive. Estimated Age of First Eruption of Mauna Loa: 1,000,000 - 700,000 years before present. The age of earliest subaerial eruptions: 400,000 years ago. Mauna Loa rises 9 km above the sea floor. The weight of the massive mountain has depressed the oceanic crust down by about 8 km. Oldest Dated Rocks: between 100,000 and 200,000 years ago. Mauna Loa volcano stage: Shield-forming stage. Mauna Loa's magma comes from the Hawaii hotspot, which has been responsible for the creation of the Hawaiian island chain over tens of millions of years. The drift of the Pacific Plate will carry Mauna Loa volcano away from the Hawaii hotspot within 500,000 – 1,000,000 years from now, at which point it will become extinct.
The Hawaiian Volcano Observatory monitors Mauna Loa volcano since 1912. Hawaii Volcanoes National Park covers the summit and the southeastern flank of Mauna Loa volcano, and Kilauea volcano.
Mauna Loa shield volcano has erupted some three dozen times since its first well-documented eruption in 1843. Many of its eruptions are confined within Mokuaweoweo Caldera; others are lower flank eruptions along northeast or southwest rift zones.
Mauna Loa volcano Historical eruptions: 1843, 1849, 1851, 1852, 1855-56, 1859, 1865-66, 1868, 1870(?), 1871, 1872, 1873, 1873-74, 1875, 1876, 1877, 1879, 1880, 1880-81, 1887, 1892, 1896, 1899, 1903, 1907, 1914-15, 1916, 1919, 1926, 1933, 1935-36, 1940, 1950, 1975.
The most recent eruption of Mauna Loa volcano: March 24-April 15, 1984.
Re-inflation of Mauna Loa's shallow magma storage reservoirs started immediately following the most recent eruption in 1984, and then turned to deflation for almost a decade. In mid-2002, inflation started again, just after a brief swarm of deep long-period earthquakes.
May 20, 2003. After nearly 10 years of slight deflation, inflation was observed where lengthening of the lines across the summit caldera was monitored. Magma replenishment within the volcano's reservoir may be the cause of inflation.
In late February 2003, inflation once again occurred at Mauna Loa's Moku`aweoweo summit caldera. Swelling of the volcano's magma reservoir created lengthening, uplift and tilting. Seismicity stayed at low levels.
A more intense swarm of several thousand deep long period earthquakes occurred in late 2004, immediately preceding a dramatic increase in inflation rate. Inflation slowed again in 2006, ceased altogether in late 2009, and resumed slowly in late 2010.
Mauna Loa volcano and Kilauea volcano are dynamically coupled.
Hawaiian Mauna Loa and Kilauea volcanoes has its own separate, shallow magma chambers. But 80 km down, in the asthenosphere, Mauna Loa and Kilauea are dynamically coupled. There is melt that extends beneath both volcanoes. Changes in pressure transmitted to both volcanoes. The Hawaiian Islands are hotspot volcanoes, formed as the Pacific plate moves over a plume of hot magma in the mantle. Pressure changes in the pooled magma in the mantle could rapidly affect both volcanoes. When one volcano inflates, the other starts to bulge about six months later.
When one volcano is active, the other volcano is quiet. Eruptions at one volcano release pressure in the other. After Mauna Loa eruption in 1984, volcano had accumulated enough magma for another eruption, but its pressure relieved by Kilauea volcano heightened activity. The summit of Kilauea volcano has recently started inflating. If Kilauea volcano continues to inflate like it is right now then another period of inflation at Mauna Loa in about short time.
Mauna Loa shield volcano has erupted some three dozen times since its first well-documented eruption in 1843. Many of its eruptions are confined within Mokuaweoweo Caldera; others are lower flank eruptions along northeast or southwest rift zones.
Mauna Loa volcano Historical eruptions: 1843, 1849, 1851, 1852, 1855-56, 1859, 1865-66, 1868, 1870(?), 1871, 1872, 1873, 1873-74, 1875, 1876, 1877, 1879, 1880, 1880-81, 1887, 1892, 1896, 1899, 1903, 1907, 1914-15, 1916, 1919, 1926, 1933, 1935-36, 1940, 1950, 1975.
Re-inflation of Mauna Loa's shallow magma storage reservoirs started immediately following the most recent eruption in 1984, and then turned to deflation for almost a decade. In mid-2002, inflation started again, just after a brief swarm of deep long-period earthquakes.
Hawaiian Mauna Loa and Kilauea volcanoes has its own separate, shallow magma chambers. But 80 km down, in the asthenosphere, Mauna Loa and Kilauea are dynamically coupled. There is melt that extends beneath both volcanoes. Changes in pressure transmitted to both volcanoes. The Hawaiian Islands are hotspot volcanoes, formed as the Pacific plate moves over a plume of hot magma in the mantle. Pressure changes in the pooled magma in the mantle could rapidly affect both volcanoes. When one volcano inflates, the other starts to bulge about six months later. 
