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Mid-ocean Ridges

Bathymetric image of the East Pacific Rise, a mid-oceanic ridge located along the floor of the Pacific Ocean. (Image courtesy of Haymon et al., NOAA-OE, WHOI)

The mid-ocean ridge is a continuous range of undersea volcanic mountains that encircles the globe almost entirely underwater. It is a central feature of seafloor terrain that is more varied and more spectacular than almost anything found on dry land, and includes a collection of volcanic ridges, rifts, fault zones, and other geologic features.

At nearly 60,000 kilometers (37,000 miles) long, the mid-ocean is the longest mountain range on Earth. It formed and evolves as a result of spreading in Earth’s lithosphere—the crust and upper mantle—at the divergent boundaries between tectonic plates. The vast majority of volcanic activity on the planet occurs along the mid-ocean ridge, and it is the place where the crust of the Earth is born. The material that erupts at spreading centers along the mid-ocean ridge is primarily basalt, the most common rock on Earth.

Because this spreading occurs on a sphere, the rate separation along the mid-ocean ridge varies around the globe. In places where spreading is fastest (more than 80 millimeters, or 3 inches, per year), the ridge has relatively gentle topography and is roughly dome-shaped in cross-section as a result of the many layers of lava that build up over time. At slow- and ultra-slow spreading centers, the ridge is much more rugged, and spreading is dominated more by tectonic processes rather than volcanism.

Scientists study the physics, chemistry, and biology of mid-ocean ridges gain insight into how Earth works in very fundamental and often surprising ways.

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News & Insights

Wave Glider provides gateway to remote exploration

WHOI geochemist Chris German pairs an autonomous surface vehicle (ASV) called a Wave Glider with other vehicles to expand research here and on other Ocean Worlds

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News Releases

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WHOI in the News

The 40,000-Mile Volcano

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From Oceanus Magazine

Racing an undersea volcano

Using AUV Sentry to make a high-resolution, near-bottom, seafloor map before the next volcanic eruption at the East Pacific Rise

How Is the Seafloor Made?

An ultrasound for the Earth? Using sound waves, a graduate student peers into the crystalline texture of the tectonic plates that cover our planet’s surface.

Pop Goes the Seafloor Rock

WHOI scientists used the human-occupied submersible Alvin and the autonomous underwater vehicle Sentry to explore a surprising discovery: gas-filled volcanic rocks on the seafloor that “pop” when brought up to the surface.

Deep-sea Detectives

Links to related materials Mid-Ocean Ridges—Articles, illustrations, and video showing how new seafloor crust forms Mapping the Seafloor with Multibeam Sonar Profile of Marshall Swartz Story of the SDSL Data-Link Life at Vents and Seeps While Oil Gently Seeps from the Seafloor—Oceanus magazine story about natural seeps of oil and methane

Deep-sea Vents Yield New Species

Call it “midnight at the OASES.” Neither permanent darkness nor extreme pressure and heat cause problems for a host of new deep-sea species found in January by an international research expedition called “OASES 2012.” The expedition, led by Woods Hole Oceanographic Institution geochemist Chris German, explored hydrothermal vents on the seafloor in the Caribbean, which…