The Ocean Floor Dropped 13 Feet in Six Days

Two months after researchers lowered a custom-built geodetic observatory to the bottom of the Indian Ocean, the valley floor dropped about 4 meters (13 feet) in six days, with most of that drop happening in the first 16 hours alone. The planet was remaking itself, and for the first time, someone was watching.

Mid-ocean ridges form where two tectonic plates pull away from each other. Magma bubbles up in between, solidifies and turns into new oceanic crust, a process called seafloor spreading that has been building ocean basins for billions of years. The problem is that it happens in some of the most inaccessible places on Earth, so no one had ever actually seen it happen in real time. Until April 2024.

Marine geophysicist Jean-Yves Royer's team deployed their instrument array at the Southeast Indian Ridge, between Antarctica and Australia, and then did what scientists do: they waited. Mapping of the seafloor before and after the event suggests that around 5.7 billion cubic feet of lava, roughly 65 times the volume of the Great Pyramid of Giza, emerged in about 16 days to form new seafloor. Royer had been expecting to measure a few centimeters of horizontal displacement. What he got was the crust tearing apart at half a million times the normal spreading rate.

One other twist: the discovery also helps explain why undersea faults produce far fewer earthquakes than expected. Most of the action happened silently: quiet fault slips and magma forcing through cracks, no shaking required. The earthquakes came later, after the magma reservoir emptied and the seafloor above it collapsed.

The Southeast Indian Ridge has probably been doing this for millions of years without anyone this close to record it.

Read the full story at Popular Mechanics, July 29, 2026

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