Monterey Bay Aquarium Research Institute
Submarine Volcanism
Mid-ocean ridge research
Knobby Pillow
Knobby lava pillow draped over a rounded pillow, seen by ROV Tiburon on our Gorda 2002 expedition
Image © 2002 MBARI
Vent fauna
Animals on a hydrothermal vent chimney on our Gorda 2000 expedition
Image © 2000 MBARI

Volcanism at mid-ocean ridges

The great majority of the Earth's volcanism occurs at spreading centers, most of which are under the ocean, forming the mid-ocean ridge system where new ocean crust is being created. The Earth's tectonic plates are slowly moving apart, and magma rises up to fill the gap, adding to the deep crust as sheeted dikes and sometimes flowing onto the seafloor as volcanic eruptions. The shallow magma provides a heat source that causes intense circulation of water within the shallow oceanic crust and the venting of the heated, mineral-laden water at the seafloor. These hot springs and spectacular hydrothermal vents transport heat and chemicals into the ocean and provide substrate for chemosynthetic biological communities.

The Gorda, Juan de Fuca and Endeavour Ridges have slow (~25 mm/yr) to moderate spreading rates, and are located off Oregon and Washington states and British Columbia. The Northern East Pacific Rise has a fast spreading rate, and is located off Mexico, south of the Gulf of California. Segments of the Southern East Pacific Rise have super-fast spreading rates (>140 mm/yr), the fastest of which are south-west of Easter Island in the South Pacific.

Note that off-axis, near-ridge seamounts are discussed in the Seamounts section of this web.

In these pages: our research on mid-ocean ridges

Related links

From our group's expeditions to mid-ocean ridges:

MBARI mapped Axial Volcano on expeditions from 2006 to 2011

MBARI has mapped the Gorda and Juan de Fuca Ridges with hull-mounted high resolution multibeam sonar 

newA special volume of the journal of The Oceanography Society is focused on spreading centers, and is available for free download. Articles to which we contributed:

  • Endeavour Segment of the Juan de Fuca
  • Volcanic eruptions in the deep sea
TOS Spreading Center Processes

For more background information, visit

| Hot spots | Mid-ocean ridges | Seamounts | Margin |

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Questions? Comments? Please contact Jenny Paduan
Last updated: Jun. 18, 2014