A Newly Formed Volcano Has Been Discovered on the Oldest Part of the Pacific Plate

A small, young volcano has been discovered deep beneath the ocean at the oldest part of the Pacific plate. The volcano, which is about 1,500 feet in height and is known as a petit-spot volcano, is thought to have last erupted less than three million years ago.

These types of volcanoes are a relatively new discovery, with the first having been found in 2006 by a team of Japanese researchers. Petit-spot volcanoes appear along the base of tectonic plates. As plates sink into the mantle and bend, fissures open up resulting in small volcanoes.

In a study published in the journal Deep-Sea Research Part I: Oceanographic Research Papers, the same team of Japanese researchers has reported another example. This volcano was found near the Mariana Trench close to Marcus Island—Japan's most easterly point. This area was previously thought only to contain islands and seamounts that formed over 70 million years ago.

Lead author Naoto Hirano, from the Center for Northeast Asian Studies at Tohoku University, told Newsweek that these types of volcanoes are ubiquitously distributed across the ocean where tectonic plates are bending. "But it is difficult to detect the presence in submarine environment because they are too small—only a few to 10 kilometers (1.2 to 6 miles) in diameter."

Hirano said it is not possible to detect them using Google Maps, utilizing submarine topography via the satellite data, because the resolution is too low.

Petit-spot volcanoes, the research team say, provide an interesting insight into the uppermost part of Earth's mantle—the asthenosphere. This layer is about 110 miles thick, pliable, and is thought to drive the movement of tectonic plates. By looking at these volcanoes, scientists can better understand the processes that drive the melting process and movement of the plates.

Lava flow from the newly discovered volcano. Tohoku University

"By seismic observation, the asthenosphere has been observed [to be a] 'ductile' zone below the rigid tectonic plate, driving plate tectonics," Hirano said. "But nobody knows what kind of rocks [are] there." These rocks found in the petit-spot magma come from the asthenosphere, he added.

The team identified the volcano after underwater topography data collected by the Japan Coast Guard suggested something unusual was sitting on the seafloor. The team then sent a manned submersible down to the seafloor to collect rock samples. Findings showed a volcano measuring 1,500 feet in height, with ridges extending 2.6 miles to the northeast and 3.4 miles to the south. The volcano is part of a cluster that spans between 24 and 62 miles wide, Hirano said.

It is not clear what the fate of the volcano will be, Hirano said. It may never erupt again, while another petit-spot volcano may form somewhere else in the cluster. "The discovery of this new volcano provides an exciting opportunity for us to explore this area further, and hopefully reveal further petit-spot volcanoes," Hirano said in a statement. "This will tell us more about the true nature of the asthenosphere."