Earth now has one of solar system's biggest volcanoes

Deep in the Pacific Ocean, Tamu Massif is an inactive volcano that's as big as New Mexico and comparable to the massive Olympus Mons on Mars.

Tamu Massif
An enormous feature in the northern Pacific, Tamu Massif has been confirmed as the largest single volcano on Earth. Image courtesy William Sager

Scientists have discovered a staggering colossus that once spewed fire but now slumbers deep in the Pacific Ocean. Sadly it's not Godzilla, but it is a volcano with a footprint comparable to Olympus Mons on Mars, the largest volcano in the solar system.

Covering an area of 120,000 square miles, which makes it about the size of New Mexico or the British Isles, the formation dubbed Tamu Massif is one of the biggest ever found, according to a study led by University of Houston professor William Sager.

"We show that the Tamu Massif is a single, immense volcano, constructed from massive lava flows that emanated from the volcano center to form a broad, shield-like shape," Sager and colleagues write in Nature Geoscience (PDF).

"We suggest that the Tamu Massif could be the largest single volcano on Earth and that it is comparable in size to the largest volcano in the solar system, Olympus Mons on Mars."

Hawaii's Mauna Loa, the largest active volcano on Earth, is taller than Tamu Massif but has only about 2 percent of its area.

Located 1,000 miles east of Japan, the gently sloping Tamu (an acronym for Texas A&M University, where Sager worked) is part of an underwater mountain range called the Shatsky Rise that was formed 130 million to 145 million years ago.

Tamu's summit is roughly 6,500 feet below the ocean's surface. Most of the formation is thought to be in waters that are nearly 4 miles deep.

Researchers had long pondered whether it was one volcano or a collection of many. Core samples and other data convinced the Sager team that the giant mass of basalt, which is low and broad, originated from a single source near the center.

Tamu Massif core samples
IODP technician Margaret Hastedt labels core samples from Tamu Massif aboard the drillship JOIDES Resolution. The samples suggested lava flows up to 75 feet thick. Integrated Ocean Drilling Program/U.S. Implementing Organization

In 2010 and 2012, Sager and his collaborators fired air guns to send seismic waves deep into the formation, and found that all the lava flows flowed away from the summit, suggesting a central magma vent.

The core samples were obtained during the Integrated Ocean Drilling Program (IODP) Expedition 324 (Shatsky Rise Formation) from the research vessel JOIDES Resolution in 2009.

"Tamu Massif is the biggest single shield volcano ever discovered on Earth," Sager said in a release. "There may be larger volcanoes, because there are bigger igneous features out there such as the Ontong Java Plateau, but we don't know if these features are one volcano or complexes of volcanoes."

"Its shape is different from any other sub-marine volcano found on Earth, and it's very possible it can give us some clues about how massive volcanoes can form," he added.

"An immense amount of magma came from the center, and this magma had to have come from the Earth's mantle. So this is important information for geologists trying to understand how the Earth's interior works."

 

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