A September 5 news release from the University of Houston (UH) details the discovery and confirmation of the largest single volcano documented on Earth. The finding is the result of a research team effort led by William Sager, a UH professor of Earth and Atmospheric Sciences, who first began examining the inactive volcano – named Tamu Massif – two decades ago while a professor in the College of Geosciences at Texas A & M. The findings of the research effort will appear in the September 8 issue of the journal Nature Geoscience.
Tamu Massif covers an area approximately the size of New Mexico, placing it among the largest volcanoes in our Solar System. Located roughly 1,000 miles east of Japan, the volcano is the largest feature of Shatsky Rise, an undersea mountain range formed by the eruption of multiple underwater volcanoes some 130 to 145 million years ago.
The study confirms that Tamu Massif was a single volcano, putting to rest scientific debate that it may have instead been a composite of several eruption points. Through assimilating several sources of evidence, comprising core samples and data collected on board the JOIDES Resolution research ship, the research team confirmed that the mass of basalt that constitutes Tamu Massif did indeed erupt from a single source near the center.
“Tamu Massif is the biggest single shield volcano ever discovered on Earth,” said Sager. “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.”
Tamu Massif distinguishes itself among underwater volcanoes not only for its size, but also for its shape. Its low and broad features suggest that the erupted lava traveled long distances compared to most other volcanoes on Earth. The ocean floor is peppered with thousands of underwater volcanoes, or seamounts – most of which are small and steep compared to the low, broad span of Tamu Massif.
“It’s not high, but very wide, so the flank slopes are very gradual,” said Sager. “In fact, if you were standing on its flank, you would have trouble telling which way is downhill. We know that it is a single immense volcano constructed from massive lava flows that emanated from the center of the volcano to form a broad, shield-like shape. Before now, we didn’t know this because oceanic plateaus are huge features hidden beneath the sea. They have found a good place to hide.”
Tamu Massif occupies an area of approximately 120,000 square miles. Hawaii’s Mauna Loa – the largest active volcano on Earth – is approximately 2,000 square miles, or roughly two percent the size of Tamu Massif. To locate a comparable behemoth, one must look to the planet Mars, home to Olympus Mons. This immense volcano, which is visible on a clear night with a standard backyard telescope, is 25 percent larger by volume than Tamu Massif.