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ANALYSIS | Hawaiian volcano eruption is explosive evidence of plate tectonic theory | CBC Radio


The present eruption of Mauna Loa on the Huge Island of Hawaii is a part of a protracted historical past of volcanic exercise that fashioned the Hawaiian chain and is a vivid demonstration that the large plates of the Earth’s crust transfer over time.

In the event you have a look at a map of the Hawaiian islands, you will note they kind a sequence that runs in a northwesterly route, with Huge Island on the southern finish of the chain. It’s also the one island within the group that’s volcanically lively. 

This chain of islands in the course of the Pacific Ocean got here to the eye of Canadian geologist John Tuzo Wilson who, in 1963, proposed the concept that the islands had been created by a really lengthy lasting and very scorching spot within the Earth’s mantle. His thought was {that a} plume of molten magma that rises up from deep inside the Earth and had punched a gap by the overlying crust. 

Aerial footage of Mauna Loa volcano erupting on Dec. 1, 2022. The eruptions started on Nov. 27. (USGS)

As the recent lava flows upwards over hundreds of years, it builds up right into a volcanic mountain that finally pokes by the ocean floor, forming an island.

This course of continues immediately with the latest eruptions on the summit of Mauna Loa, and with ongoing eruptions on Kilauea, situated on the opposite aspect of Huge Island. In different phrases, Huge Island is getting larger.

However Wilson noticed one thing extra than simply the recent spot punching holes within the crust. He noticed the Hawaiian island chain as the results of a sequence of holes based mostly on the truth that rocks on the opposite islands turn into progressively older as you go north. These on Kauai, the northernmost inhabited island, are about five-and-a-half million years outdated, whereas these on Huge Island are lower than a million years outdated.

Onlookers watch as lava from a Kilauea volcano fissure erupts in Leilani Estates, on Hawaii’s Huge Island, in Could 2018. (Mario Tama/Getty Photographs)

He argued that the ground of the Pacific Ocean has been slowly shifting northwest, so after one volcano is constructed, the ocean flooring strikes over the stationary hotspot and one other volcanic island types. Over hundreds of thousands of years, a sequence of islands fashioned throughout the ocean. Consider shifting a sheet of paper over a candle, the place the flame can burn a sequence of holes by the paper because it strikes. 

One other scorching spot is believed to put beneath Yellowstone Nationwide Park and is liable for the quite a few scorching springs and geysers within the space. 

The idea that the ground of the Pacific Ocean is shifting supplied assist to the idea of continental drift, which was hotly debated amongst geologists proper into the Nineteen Sixties. Wilson was instrumental in growing it additional into the present idea of plate tectonics, through which the crust of the Earth is damaged into continent-sized items that transfer round, slowly altering the face of the planet. 

Guests at Yellowstone Nationwide Park are engulfed by thermal steam at this volcanic hotspot. (Invoice Schaefer/Getty Photographs)

The present eruption on Mauna Loa is, in geologic phrases, kind of a final gasp as a result of a brand new volcano, Kama’ehuakanaloa — previously often called Loihi — is forming to the south of Huge Island.

It rises greater than 3,000 metres above the ocean flooring, however its summit remains to be a few kilometre beneath the floor of the ocean. It’s fed by the identical hotspot, in order the Pacific plate continues its gradual motion north, Kama’ehuakanaloa may burst above the waves someday sooner or later. 

The Huge Island of Hawaii is an efficient place to go if you wish to see eruptions in motion, however finally, these volcanoes will go quiet. Nevertheless, in case you stick round for an additional 10,000 years or so, Kama’ehuakanaloa may turn into the island the place folks go to see the spectacular sight of the Earth constructing new land. 


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