Mapping the Seafloor

The Global Mid-Ocean Ridge and Submersible Seafloor Robotics

The world’s longest mountain range remains unseen by most due to its location in the vast depths of the ocean. At 3,700 miles long, the Global Mid-Ocean Ridge circles the globe almost entirely underwater, extending from the Arctic Ocean to the Atlantic Ocean, around Africa, Asia and Australia, and under the Pacific Ocean to the west coast of North America.

This massive mountain range is also the largest single volcanic feature on Earth, with an estimated 20 volcanic eruptions occurring every year. If you’ve never heard about these underwater eruptions, it’s not because you’re watching the wrong news station. They typically go unnoticed by humans since most of the ridge is more than 6,562 beneath the water’s surface.

The volcanic activity is the result of the constant movement of the Earth’s crust along the Global Mid-Ocean Ridge. It continually spreads, creating new layers of the seafloor and recycling the older crust back into the mantle—American oceanographer Bruce C. Heezen once described it as “the wound that never heals.” This process of seafloor spreading eventually evolved into today’s theory of plate tectonics.

Depending on what part of the ridge you’re exploring, its shape could appear smooth or rugged—its morphology varies by location. Scientists theorize that the strength of the ocean crust, and how cold and brittle the upper part of the tectonic plate is, ultimately determine the shape of these underwater mountains.

To explore the Mid-Ocean Ridge and the rest of the surprisingly unmapped seafloor, scientists are employing the use of new submersible technology. Autonomous underwater vehicles, or AUVs, were first created in 1957 and have recently been used to develop a detailed image of the seafloor. These programmable, robotic vehicles are designed to drift, drive or glide through the water without the guidance of human operators.

While scientists are conducting their own research on the surface of the water, an AUV can be collecting data in the ocean’s depths. Some of these robots can even decide to change their mission profile based on the environmental data they receive. AUVs have the potential to provide us with a more detailed map of the 70 percent of the Earth that’s covered by water. By accurately measuring water currents and clarity, chlorophyll, temperature and salinity in three-dimensional space, AUVs can create a compact, high-resolution snapshot of the seafloor that’s difficult to produce on a surface ship.

AUVs have also proven useful in the search for missing planes. Two years after Air France Flight 447 disappeared off the coast of Brazil in 2009, searchers found the flight data recorder and the majority of the wreckage by using an AUV. You may have heard the acronym used in recent news reports about the search for the missing Malaysia Airlines Flight 370.

While AUVs offer endless possibilities in the uncovering of our ocean’s mysteries, we still have a long way to go. More research and development is necessary for these underwater robots to become standard hydrographic tools.


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