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Probably when you think of a volcano, you might imagine a stratovolcano, as the Teide or the Vesuvius, a conical mountain formed by very violent eruptions. But the reality is much more complex: the greater part of the lava generated on the planet is released through fissures submerged in the ocean. In addition, the vast majority of Earth’s volcanoes are in the Pacific Ring of Fire, a costurón 40,000 miles long that runs things in America, Japan and New Zealand: There you accumulate 425 volcanoes, 75% of all of them, and occur 90% of the earthquakes.

therefore, to identify the greatest volcano of the Earth, not just look at the highest mountain: you have to have very in account the part that is submerged under the sea, or even in the basement. By this, a group of researchers from the University of Hawaii at Manoa, Honolulu, has been able to identify which volcano is the most massive of the Earth: it is Pūhāhonu , a submerged volcano located in the northwest of the archipelago of Hawaii, in the united States. Their findings were recently published in “Earth and Planetary Science Letters”.

“New bathymetric data –from the depths– and the maps of gravity, as well as the calculations more refined on the volume and the analysis of petrology –the study of the composition of the rocks– shows that the volcano Pūhāhonu is the largest and the most hot of the Earth “, are written by the authors of the study, led by Michael O. Garcia.

The turtle that comes out to breathe

From the surface, Pūhāhonu is not very spectacular. Who browse through your nearby 952 kilometers northwest of Honolulu, you will only see two islets, barely rising 50 meters above the sea level and in the dock the seagulls and the beings that live embedded in rocks. His humble attitude he explained that his name means “turtle rising to breathe”, in hawaiian.

The humble summit of the volcano Pūhāhonu, 952 kilometers northwest of Honolulu, Hawaii – NOAA

But in the darkness, under the waters, hides the most monstrous “belly” of magma that have been observed up to now in the planet. The analysis has revealed that their size is almost two times higher than that of Mauna Loa, another volcano on the hawaiian which until now was regarded as the greatest of the Earth, and rises almost nine kilometres above the ocean floor, more than Mount Everest.

In fact, researchers have located the volume of Pūhāhonu between the 119.000 and to 177,000 cubic kilometers , while Mauna Loa has 74.000. That is to say, Pūhāhonu can be up to two times greater than that which until now was thought to be the largest volcano.

So massive that it doubles the cortex

Pūhāhonu barely sticking out “to breathe”, but its roots go much into the depths. The researchers have concluded that only 30% of its volume sticking out on the ocean floor , while the rest is hidden below. In fact, they have concluded that the mass of the volcano is so huge that it has sunk the earth’s crust a few kilometers, in the course of 14 million years in which it was formed.

In red, the massive buildup of magma from the volcano Pūhāhonu – Michael O. Garcia et al. 2020

The presence of olivine and other minerals in some rocks suggests, according to the authors, that the magma of this volcano was very hot, to about 1,700 ° C, more than any other hawaiian volcano. This is an important clue that indicates what could be the origin of the Pūhāhonu.

The spectacular origin of Hawaii

To understand is that situarle in its context. The archipelago of Hawaii is part of one of the volcanic most studied: the Chain of seamounts Hawaiian-Emperor . This system is the result of a “hot spot”: an area where a pen mantélica, a kind of fissure that amounted materials very hot interior of the planet, was passing through the earth’s crust, creating volcanoes.

Interestingly, while the pen was in more or less the same point, the Pacific tectonic plate was moving, so that the pen was creating a chain of underwater mountains 6,200 miles of long, ranging from Hawaii to the Aleutian islands, off the eastern coast of Russia. There are four voclanes assets, two asleep and 123 extinct: the majority of them have the appearance of atolls or seamounts.

Depending on what you have observed to these researchers, the magma reached temperatures that indicate that the process that gave birth to Pūhāhonu happened at once: a single “wave” of magma ascended, increased the diameter of the core material and created a layer of insulation to further increased temperatures.

A plume of 2,000 kilometres of depth

The researchers acknowledge that the Chain of seamounts Hawaiian-Emperor is one of the places where a better has studied the effect of a feather mantélica on the surface. But they argue that even today you can continue to discover interesting details on this part as relevant to the planet, to achieve “a more complete understanding of the mechanical and the thermal evolution of the feathers of the mantle”.

it Is estimated that the pen of this hot spot has 500 to 600 kilometers wide and up to 2,000 kilometers deep. In its 85 million years of activity, has created approximately 750,000 cubic kilometers of rock. A tiny part of them today is the largest volcano of the Earth: his name is Pūhāhonu.