Let's begin with a brief concept of mantle plume. It is the upwelling mechanism of extremely hot magma within the mantle of earth. A superplume often acts as the cause of volcanism. For instance, Tibesti in central Sahara, Hawaii Island, etc. are situated over such gigantic superplume.

However, geologists have recently conducted a study which reveals an inconceivable fact. Their research paper unveil that New Zealand, the country of Oceania in the south-western Pacific Ocean, is actually situated upon such a primitive superplume.


The research paper, entitled as ‘High mantle seismic P-wave speeds as a signature for gravitational spreading of superplumes’, was published by American Association for the Advancement of Science, on 27th May 2020. Tim Stern from the Institute of Geophysics, Victoria University of Wellington, and other co-researchers have made this understandable to us.

New Zealand is basically the outstretched part of the Hikurangi Plateau above the ocean surface. Hikurangi Plateau is an oceanic plateau in the south-western Pacific Ocean. It was formed due to an enormous magma eruption, most probably during well known Cretaceous period of dinosaurs, 145 million years ago.


Bathymetry and topography of the south-west Pacific region
| Image Courtesy :

The recently concluded study stressed on the acquisition of something crucial information. They have examined seismic P-wave which can penetrate through all types of substances.

Early since the 70s of the last century, an usual 8.5-9 kilometres per second speed of P-wave was recorded within the upper mantle just beneath the North Island of New Zealand, but that was only unidirectional penetration of the high speed wave vibration, and its tenor was not quite clear.


Henceforth, the recent observation of P-wave in both horizontal and vertical directions have opened up some exciting findings. The wave incessantly go through at a speed of around 9 kilometres per second in its horizontal direction, but it seems to be obstructed by deep earthquake in its vertical flow.

This might be the consequenc of the development of almost flat headed plume.


Computer simulations of plume upwelling | Image Courtesy : Sciencealert

This seismic analysis of researchers suggest that the whole region, along with two other oceanic plateau in the south-western Pacific region – Ontong Java and Manihiki – are lying above that gigantic flat-headed plume that originated from deep into the lower mantle.

However, scientists mentioned that some other islands in the south-western Pacific region are also lying above the superplume remnants. In spite of these, they are also in search of other discoveries to provide further insights about earth's interior.

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