Oceanographers often point out that scientists have mapped the surfaces of the Moon and Mars in more detail than much of Earth’s deep ocean. This contrast is particularly striking in the Bismarck Sea, north of Papua New Guinea, despite its incredible geological complexity. The region includes faults, volcanic structures, fissures, scarps, and active subduction and spreading zones, many of which are located at depths that make detailed sonar mapping extremely difficult.
This lack of knowledge became especially clear when satellites detected signs of an unexpected undersea volcanic eruption in the central Bismarck Sea on May 8, 2026. Researchers believe the activity is occurring along Titan Ridge, about 16 kilometers (10 miles) southeast of the site of another underwater eruption in 1972. Still, scientists still cannot say with certainty which volcanic features are erupting, how deep the active vents were to begin with, or when they last erupted.
“The good news is that there is tremendous opportunity to explore and learn using both government and commercial satellite platforms already in orbit,” said Jim Garvin, chief scientist at NASA Goddard Space Flight Center.
Satellite reveals eruption from space
Seismographs recorded the first small earthquake swarm on May 8th. Satellite observations soon confirmed that an undersea eruption was in progress.
Starting May 9, NASA’s Aqua and Terra satellites captured images of white, vapor-rich plumes rising into the atmosphere. At the same time, an ocean color sensor aboard NASA’s PACE (Plankton, Aerosols, Clouds, and Marine Ecosystems) satellite detected widespread discolored and turbulent waters around the eruption site.
Other satellites soon spotted the plume reaching several kilometers into the sky. High-resolution images collected by the European Space Agency’s Sentinel 2 satellite and NASA/USGS Landsat 9 on May 10 and 11 provided a detailed picture of near-surface activity. The pseudocolor image (bands 7-6-5) highlighted the infrared signature of the eruption. Then, on May 12, the VIIRS (Visible Infrared Imaging Radiometer Suite) instrument aboard the Suomi nuclear power plant identified a thermal anomaly covering approximately 7 square kilometers.
“There must be a lot of hot material near the surface to cause so many thermal anomalies,” said Simon Kahn, a volcanologist at Michigan Technological University. “This suggests a fairly shallow crater, much shallower than existing bathymetric measurements suggest, which indicate depths of hundreds of meters or more.”
Is it possible that new islands are forming?
Satellite images also revealed intense activity on the ocean surface. Large columns of discolored water, numerous steam and ash vents, and extensive pumice rafts (floating volcanic rock) have all been observed. Medium- and high-resolution sensors operated by government agencies and commercial satellite companies have tracked these floating pumice fields, which extend into long bands carried by surface currents.
“We’re now waiting to see if new islands are about to form, and it’s rare that we can watch that happen with satellites,” Garvin said.
If land appears above water, scientists will closely monitor how it develops. Volcanoes can build tuff cones with long-lived craters, or new land can quickly collapse and erode. If seawater reaches the shallow magma chambers that develop within growing submarine volcanoes, eruptions can also become significantly more explosive.
Why did this eruption remain relatively calm?
So far, this eruption has been much less explosive than recent undersea eruptions, such as the 2022 Hunga Tonga-Hunga Ha’apai eruption and the 2021 Huktoku-Okanobain eruption.
Kahn said the eruption is associated with a volcanic ridge near the intersection of a transform fault and a back-arc spreading center, so dramatic expansion is unlikely.
“Spreading centers are not associated with as much explosive activity, but the most explosive eruptions usually occur along subduction zones and involve large stratovolcanoes.”
Scientists also don’t know how long the eruption will last. A nearby submarine eruption in 1972 lasted only four days, while another eruption about 100 kilometers away in the St. Andrew Sound began in 1957 and lasted almost four years.
A rare opportunity to learn about a new island
Garvin and researchers from several institutions continue to closely monitor the eruption. He plans to use radar data from the NASA-ISRO NISAR satellite and the Canadian Space Agency’s RADARSAT constellation mission to map newly rising land above the ocean and measure how its shape changes over time.
If the eruption were to form a permanent island, Garvin believes it could become an extraordinary natural laboratory. Researchers he calls “island aviators” could study how plants and animals colonize new land, how rainfall and chemical weathering change the landscape, and how erosion changes islands over time, just as scientists did after the Hunga-Tonga-Hunga-Ha’apai eruptions.
“This new eruption could be an even better opportunity for Island Astronaut exploration as we prepare to return to the Moon with the men and women on Artemis IV,” he said.
