Over the past summer, scientists on the research vessel Marcus G. Langseth created a 3D map of Axial Seamount, an undersea volcano 300 miles off the Oregon coast.
Easier said than done, given that Axial rests 4,626 feet beneath the waves. The volcano was discovered in 1981, and has erupted three times since then: first in 1998, then again in 2011 and 2015. Indeed, Axial is one of the most active undersea volcanoes in the world, due to its unique location at the junction of a mantle plume and a mid-ocean ridge.
To get an accurate map, the ship had to tow four cables equipped with pneumatic air guns. The guns generated acoustic pulses which bounced off of the volcano, a la sonar, and were picked up by receivers in the cables.
The researchers had to be wary of fouling the cables, as well as any present sea life. Since marine mammals rely upon echolocation, the operation shut down any time a dolphin or whale strayed within 3,300 feet.
After 33 days, the scans were complete. The map reveals that Axial’s base is as wide as the city of Austin, Texas, and its magma reservoir is two-thirds the length of Manhattan.
Axial is predicted to erupt in 2020 or 2021, but it’s too deep and too far from shore to cause any real harm. However, by studying it, scientists can plan better for more dangerous eruptions, such as Kilauea in Hawaii or Anak Krakatau in Indonesia.