image

China science

Tamu Massif even more massive: world’s largest volcano almost same size as Japan, widest in solar system

Joint China-US team hails its birth as one of the most spectacular events in earth’s history, says it is larger than Olympus Mons on Mars by surface area, describes its creation as ‘a miracle’

PUBLISHED : Thursday, 24 March, 2016, 8:31am
UPDATED : Friday, 05 August, 2016, 4:59pm

The biggest volcano on earth is larger than was previously thought, with a surface area unmatched by any in our solar system, according to a joint study by researchers from China and the United States.

They hailed its birth as one of the most spectacular events in the history of our planet, and a “miracle” of creation given its rarity.

Tamu Massif, an extinct submarine shield volcano formed about 145 million years ago during the Late Jurassic period, is located 2 kilometres below sea level between Japan and Hawaii in the Pacific Ocean.

Although there is still some dispute as to whether it can be classified as a single volcano, the possibility of this was first suggested in September 2013 and corroborated by William Sager, a marine geophysicist from the department of earth and atmospheric sciences at the University of Houston.

But after analysing more seismic data and mapping the volcano’s underlying structure, the same team found they may have underestimated the volcano’s actual size.

They put the total area of the Shatsky Rise, an elevated oceanic plateau created after the Tamu Massif erupted, at 533,000 sq km. Tamu Massif is the largest mountain on the Shatsky Rise.

Previously, the volcano was considered to be smaller overall by 20 per cent than Olympus Mons on Mars, long hailed as the largest volcano discovered in our solar system. Tamu Massif reaches a height of 4km while Olympus Mons is 22km

WATCH: Dr William Sager returns to Tamu Massif in October 2015

But the new study, led by the Chinese Academy of Sciences’ South China Sea Institute of Oceanology in Guangzhou, in southern China’s Guangdong province, claims that the surface area of Tamu Massif should now be 80 per cent larger than its Martian relative.

“Tamu Massif created a much wider dome. It surpasses every other known volcano in the solar system in terms of surface area,” said Dr Zhang Jinchang, lead scientist of the new study, adding that it was hard to say for certain which one is larger overall in terms of mass.

Tamu Massif is about the size of Japan, larger than Olympus Mons, Zhang said.

The latest study was published in the journal Earth and Planetary Science Letters. Professor Jun Korenaga, a geologist at Yale University in the United States, co-authored the paper.

Volcanos of such magnitude are extremely rare, and were previously considered impossible on earth. The largest active volcano today is Mauna Loa in Hawaii, which has a base measuring about 5,000 sq km. It is only one seventieth the size of Tamu Massif

WATCH: the eruption of Hawaii’s Mauna Loa, the world’s largest active volcano

Moreover, of the two ways volcanoes were known to be formed, neither was considered able to generate enough substance from the earth’s mantle - a silicate rocky shell measuring thousands of kilometres thick - to form one of such magnitude as Tamu Massif.

Scab theory posits that a volcano is created after the earth’s crust is torn open by the shifting of tectonic plates, allowing lava to bubble up to the surface; pimple theory states that magma moves up through a tunnel in the crust and piles in a heap on the surface.

“We are speculating that Tamu Massif may have been formed by the two mechanisms working together,” Zhang said.

“The effect would be similar to pricking the same pimple with a knife again and again for several million years,” he said.

“The chance of such an event occurring is very low - no more than one in a thousand, so it’s something of a miracle.”

Tamu Massif became extinct sometime during the Early Cretaceous period, which ended 100 million years ago, meaning it “died” just a few million years after it was born.

Fossils of marine creatures found in the underwater dome suggest its peak may, at the time, have been above the surface of the water. As such, dinosaurs could have witnessed its spectacular eruption.

But Zhang said there is no chance of the volcano coming back to life.

His study found that the Mohorovic Discontinuity (often abbreviated to Moho), a boundary between the earth’s crust and mantle, descended over 30km below the base of Tamu Massif. This would create an almost impenetrable barrier between deposits of magma and the ocean floor, he said.

Professor Zhai Shikui, a marine geologist with the Ocean University of China in Qingdao, Shandong province, praised the study for mapping the internal structure of the Shatsky Rise for the first time, but said more solid evidence would be needed to support any claim that it is a single volcano.

“Seismic analysis cannot completely rule out the possibility that [its] unique structure was created by more than one volcano. The most direct and solid evidence would need to be rock samples,” he said.