Volcano Minute is a weekly audio activity or science update produced by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.

Aloha, it's your weekly Volcano Minute, brought to you by the USGS Hawaiian Volcano Observatory. 

Beneath the ocean’s surface, submarine volcanoes carry out about 75 percent of Earth’s volcanic activity, but much of what they do remains hidden from view.

One recent example is Ruby Seamount, a submarine volcano near the Northern Mariana Islands. In September 2023, scientists detected a brief but powerful underwater eruption there. Seismic stations across the Pacific recorded explosive signals, and satellites spotted a plume of discolored water above the volcano. Then, everything went quiet.

For nearly three years, no one knew what had happened on the seafloor.

That changed in March 2026, when researchers remapped the volcano and discovered dramatic changes: landslides, fresh volcanic deposits, and a new summit crater.

The real surprise though, came four months later. A return expedition aboard the exploration vessel Nautilus found that the crater floor had risen by more than 100 meters or about 300 feet. Using a remotely operated vehicle, scientists discovered fresh lava and a newly formed lava dome. Ruby had been quietly erupting, completely undetected.

This discovery highlights how much remains unknown about submarine volcanoes and why repeated mapping and exploration are essential to understanding their growth, hazards, and hidden lives.

Meanwhile at Kīlauea, the summit eruption in Halemaʻumaʻu is paused following lava fountaining episode 55 on October 17. Reinflation rates since then suggest that another fountaining episode could happen sometime the first week of November. 

Mahalo for listening, I’m Katie Mulliken and this was your weekly volcano minute brought to you by the USGS Hawaiian Volcano Observatory.