The World’s Largest Protect Volcano Is not What We Thought It Was

Beneath the cyan and cerulean waters of the Northwestern Hawaiian Islands lurks a leviathan. Its true extent has been hidden for a few years, however no extra. What geologists have discovered is a marvel – the largest, hottest recognized volcano on the earth.

Startlingly, it is greater than twice the scale of the earlier file holder, Mauna Loa on the Island of Hawai’i. And it may change our understanding of the huge Hawaiian-Emperor seamount chain of volcanoes that span the North Pacific Ocean.

The brand new record-breaker spreads throughout round 148,000 cubic kilometres (35,507 cubic miles) beneath the waves of the Papahānaumokuākea Marine Nationwide Monument, in comparison with Mauna Loa’s 74,000.

Solely comparatively small rocky pinnacles often called the Gardner Pinnacles break the floor, giving the volcano its identify – Pūhāhonu, the Hawai’ian phrase for ‘turtle rising for breath’.

“We’re sharing with the science group and the general public that we ought to be calling this volcano by the identify the Hawaiians have given to it, quite than the western identify for the 2 rocky small islands which might be the one above sea stage remnants of this as soon as majestic volcano,” stated geologist Michael Garcia of the College of Hawai’i at Manoa.

Again within the 1970s, low-resolution bathymetric information advised Pūhāhonu was round 54,000 cubic kilometres in dimension, then regarded as the most important volcano earlier than a extra intensive survey of Mauna Loa revealed its true dimension.

Pūhāhonu solely regains its crown after intensive surveys of the area added high-resolution bathymetric and multibeam sonar information to our present understanding of the northwest Hawaiian Ridge, from which the volcano rises.

Geologists mixed this with petrologic analyses of rock samples retrieved from the volcano, refining quantity calculations and modelling based mostly on these parameters.

“It has been proposed that hotspots that produce volcano chains like Hawai’i endure progressive cooling over 1-2 million years after which die,” Garcia stated.

“Nonetheless, we now have realized from this examine that hotspots can endure pulses of soften manufacturing. A small pulse created the Halfway cluster of now extinct volcanoes and one other, a lot greater one created Pūhāhonu. It will rewrite the textbooks on how mantle plumes work.”

(Garcia et al., EPSL, 2020)

Pūhāhonu is a defend volcano, between 12.5 and 14.1 million years previous, shaped by a single magma plume surging by way of the mantle. Over the millennia, this supply regularly constructed the volcano to a top of four,500 metres (14,764 toes) from its lowest level, spanning an space 275 kilometres (171 miles) lengthy and 90 kilometres (56 miles) huge.

Chemical evaluation of rock collected from the volcano revealed a better focus of an olivine mineral known as forsterite than we have ever seen in a Hawaiian volcano. This mineral signifies magma on the upper finish of the temperature vary.

The calcium oxide content material within the forsterite allowed the crew to deduce the depth at which it shaped, confirming that it did type in magma. Simulations allowed the crew to calculate the strain at which the forsterite shaped, and the temperature.

In keeping with these calculations, the magma clocked in at 1,703 levels Celsius (three,097 levels Fahrenheit) – hotter than every other Hawaiian basalt. This excessive temperature is mirrored within the volcano’s dimension, the researchers stated.

It is a powerful beast in its personal proper. However it additionally has necessary implications for our understanding of the processes that create these unbelievable formations.

“The Hawaiian-Emperor Chain is arguably the world’s finest studied floor expression of a mantle plume,” the researchers wrote of their paper.

“Nonetheless, new insights into its magmatic and thermal historical past proceed to be revealed as extra of the Hawaiian-Emperor Chain is mapped and sampled. These insights are offering a extra full understanding of the mechanics and thermal evolution of mantle plumes.”

The analysis has been revealed in Earth and Planetary Science Letters.