‘World’s biggest volcano’ loses its title after scientists discover it didn’t form from a single eruption

The world’s largest volcano has been stripped of its title after scientists discovered it was formed by seafloor spreading instead of a single eruption.

By DIANNE APEN-SADLER FOR MAILONLINE

Tamu Massif in the Shatsky Rise, around 990 miles (1,600km) east of Japan, was declared the biggest shield volcano by University of Houston scientists back in 2013.

But after reclassifying the volcano, Mauna Loa in Hawaii, which covers 2,000 square miles – just two per cent of the size of Tamu Massif – has regained the title.

The extinct underwater volcano is around 120,000 square miles (310,000 square kilometres) in size and was formed around 145 million years ago, before going extinct a few million years after this.

It was formed above an area where three tectonic plates meet, and researchers assumed that it was created by a massive eruption from a single plume head.

To prove their theory, the group looked at magnetic anomalies in the magma that formed the 400-mile wide volcano.

Magma has magnetic material inside of it, and when it cools it aligns with wherever the poles are in that period of time.

The researchers drilled into various parts of the volcano, collecting palaeomagnetic data, and compared it to theoretically where it should have aligned with.

If it had been formed by one huge eruption, there would be no anomalies, as the magma would have been formed at the same time and therefore face the same poles.

Scientists found that this was in fact not the case, making it impossible that Tamu Massif was formed by a single eruption.

Lead author William Sager, a professor in the Department of Earth and Atmospheric Sciences at the University of Houston, told Newsweek: ‘If it formed in a short time (one polarity period), it will have a coherent overall anomaly.