Hawaii just got a new 'largest volcano on Earth.' (Condolences to Mauna Loa.)
Poking out of the sea 590 miles (952 kilometers) northwest of Honolulu, Hawaii, two barren peaks rear their heads. The little pinnacles, which stand about 170 feet (52 meters) above sea level at their highest point, bely a monstrous mountain of ancient magma beneath them. Turns out, these two unassuming nubbins are actually the tips of Pūhāhonu — the single largest volcano on Earth, scientists have found.
Pūhāhonu — meaning "turtle rising for breath" in Hawaiian — is part of the long chain of undersea mountains and volcanoes that stretch from the Hawaiian Islands to the eastern edge of Russia. Many of the chain's 120-or-so volcanoes are long dead and buried beneath the waves, though the relatively young peaks that make up the Hawaiian Islands still tower over the land (and, occasionally, blow their tops).
Mauna Loa, the gently-sloping behemoth that bulges out of Hawaii's Big Island, has long been designated the world's largest volcano. From its base on the seafloor to its summit thousands of feet over the island, Mauna Loa rises more than 30,000 feet (9,170 m) — making it technically taller than Mount Everest — and encompasses more than 19,200 cubic miles (80,000 cubic km) in volume. There's no question it's gargantuan; however, researchers now claim that Pūhāhonu actually has Mauna Loa beat — thanks largely to tens of thousands of cubic miles of volcanic rock buried beneath the ocean floor.
Related: Photos: Fiery lava from Kilauea volcano erupts on Hawaii's Big Island
In the new study, these researchers used sonar and gravity detectors to measure Pūhāhonu's entire topographic footprint, from the wee peaks standing over the sea to the deep rocks sinking hundreds of feet below the Earth's crust. The team found that Pūhāhonu contains approximately 36,000 cubic miles (150,000 cubic km) of rock — giving it a volume more than twice that of Mauna Loa.
Only a fraction of that volume — about 30% — is visible above the seafloor, the team wrote; the rest stabs so deeply underground, that Pūhāhonu has actually caused the crust beneath it to sink by hundreds of miles over the 14 million-years-or-so since the volcano formed.
"The new volume calculation shows that Pūhāhonu is substantially larger than any other Hawaiian volcano including Mauna Loa, which was presumed to be the largest volcano on Earth," the researcher wrote in the study, to be published in the July 15 issue of the journal Earth and Planetary Science Letters.
The findings get even hotter — Not only does that make Pūhāhonu the largest volcano on Earth by volume, but it may also be one of the hottest, the researchers wrote. As part of their study, the team examined several samples of olivine — a mineral that forms when magma cools and crystallizes — collected from various parts of the volcano. From the olivine's composition, the team inferred the temperature of the volcano's magma before it crystallized. They estimated that Pūhāhonu's magma must have been about 3,100 degrees Fahrenheit (1,700 degrees Celsius) when it first flowed — giving the volcano the hottest recorded magma on Earth.
Not bad for a tiny turtle head.
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Originally published on Live Science.
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Brandon is the space/physics editor at Live Science. His writing has appeared in The Washington Post, Reader's Digest, CBS.com, the Richard Dawkins Foundation website and other outlets. He holds a bachelor's degree in creative writing from the University of Arizona, with minors in journalism and media arts. He enjoys writing most about space, geoscience and the mysteries of the universe.
By Briley Lewis
By Harry Baker
Shandelles 1 has quite a lengthy swing and a miss. I recommend some classes at U.H. Hilo. Great place! As far as changing the wording on the article from "condolences" to "bigger (brother) uncle", (Uncle is more Hawaiian), that is a whole other thing. Nothing wrong with an opinion.
I don't remember the exact answer, but it is at least double (and that is probably understated by a factor of two). Mauna Loa means "Long Mountain" in Hawaiian. Perhaps that should be "Loooong Mountain". From certain directions, such as driving up the Saddle Road from the west, the two volcanoes appear to be of about the same size, but the crest of Mauna Loa is one long ridge. The profile of Mauna Kea is about the same in any direction, like that of Mt. Vesuvius (but not so steep because it is a shield volcano).
Wikipedia has a map that divides the island according to its five volcanoes. Mauna Loa is about half the projected area of the island (and more than that if one uses the surface areas of the individual mountains). Another way of putting this is that, if you wander randomly about the island (assuming you are are an expert climber), about half or more of the time you are standing on Mauna Loa lava.
I myself am not convinced that Kilauea (usually said to be the most "active" volcano in the world) should be considered independently of Mauna Loa, since it has no significant geographic prominence (i.e. no peak). It is more of bulge on the side of Mauna Loa. It is not therefore a separate and distinct mountain. This was an issue of dispute for many years, but volcanologists now seem to agree that Kilauea's underlying magma chamber is substantially independent of Mauna Loa's. Thus, it is classified as a separate volcano by them but not as a separate mountain by most geographers.
I raise this because the two islands discussed in the article might themselves be classified as distinct mountains by geographers, if measured from the ocean floor. That would depend on the depth of the saddle between them, which lies underwater. There is no universal agreement on the number that defines the required depth. The UIAA (a mountaineering society) says that a minimal descent of at least 300 meters (about 980 feet) as measured from the lesser peak defines two separate mountains. Otherwise the lesser peak is a just a sub-peak of a single mountain.
Does this mean they would also be separate volcanoes? Volcanologists apparently wouldn't care. They would ask if there were separate magma chambers for the two. This is nearly impossible to determine for extinct volcanoes, since the active magma chamber(s) is(are) long gone.
P.S. I am not a volcanologist, a geographer or a geologist. I'm just a retired chemist who lives on the island about two months of the year. If someone more expert wants to weigh in, have at it!