Largest volcano on Earth found beneath Pacific

Nature : The 4-km-high Tamu Massif is one of three mountains in an underwater range called the Shatsky Rise, located in the northwest Pacific Ocean. It had long been thought that Tamu Massif was formed from the lava of several volcanoes. But because of its remote location, it has been difficult to study its structure in more depth. In 2010 and 2012, William Sager of the University of Houston in Texas and colleagues traveled to the area on board the research vessel Marcus G. Langseth. By using air guns to fire seismic waves at the structure, they were able to determine that Tamu Massif has a central magma vent, meaning that the lava came from the mountain itself. As the lava flowed downhill, it solidified and built up the megavolcano. The megavolcano’s measured extent, 310 000 km², makes the volcano the largest on Earth. Although inactive for the past 140 million years, Tamu Massif could help geophysicists determine the amount of magma that can be stored in Earth’s crust. The researchers describe their findings in Nature Geoscience.