When scientists first got the images back from West Mata Volcano, they noticed something odd.
The undersea eruptions from two of the volcano's vents about 4,000 feet below sea level in the Pacific Ocean near Samoa were behaving very differently.
One was producing large lava bubbles that were released slowly from the volcanic vent before bursting, and the other exhibited a more chaotic, explosive release of hundreds of tiny gas bubbles.
By combining video of this eruption with sound they made over a 20-month stretch starting in 2009, scientists were able to create a unique sound signature for each eruption. The low frequency explosions were recorded on an underwater microphone during several dives of a remote operated underwater vehicle.
These acoustic fingerprints may help scientists better detect undersea eruptions and understand the different types that take place on the sea floor, according to Bob Dziak, an oceanographer at the NOAA/Pacific Marine Environmental Laboratory in Newport, Oregon, and lead author of the research published online in Geophysical Research Letters, an AGU journal.
"Detecting seafloor volcanism is important because it is a very significant process in terms of chemical impacts on the ocean and natural hazards," said Dziak, adding that volcanic eruptions on the ocean floor can significantly affect marine animals and ecosystems as well as reshape the Earth's ocean basins.
"Even though roughly 70 percent of Earth's volcanic activity occurs under the water, it has remained largely unobserved," he said. "So, the more of these events that we can detect remotely using acoustics, the more we can understand Earth's processes and how the planet works."