Conducting Science at Sea
A research vessel (R/V) is a specially designed ship equipped to conduct scientific research at sea. Research vessels are outfitted with laboratories, scientific equipment and technology to support a wide range of oceanographic studies, including biological, chemical, geological and physical oceanography. Marine research vessels are essential for collecting data on marine environments, conducting experiments and deploying instruments for underwater observation and sampling.
Interactive: R/V Marcus G. Langseth Schematics
Use buttons or mouse wheel to zoom, drag and drop to pan; select view below. View large version; Langseth specs and features
Named after a prominent geophysicist, the R/V Marcus G. Langseth is a research vessel operated by Lamont-Doherty Earth Observatory. The Langseth is equipped with advanced seismic survey technology to study the Earth’s subsurface beneath the oceans, and is capable of producing high-resolution images of geological structures deep within the Earth’s crust, which are essential for understanding tectonic processes and marine geology.
“Marine seismic imaging lets us peer beneath the seafloor, using technology similar to sonograms and X-rays,” says Lamont researcher and professor Suzanne M. Carbotte. “Just as medical tools are vital for diagnosing what happens inside the human body, seismic imaging is essential for understanding the processes occurring within the Earth. It functions as our ‘window’ into the Earth’s crust—the outer shell that supports and sustains all forms of life.”
The Langseth is used in scientific expeditions around the world, contributing valuable data to our understanding of Earth’s dynamic processes.
A Brief History of Seismic Imaging
Humans around the world have created maps of the Earth’s surface since ancient times. But mapping the Earth deep below its surface, i.e., geophysical imaging, wasn’t possible until the development of modern seismology in the late 19th century. Seismology is the scientific study of earthquakes and the generation and propagation of seismic waves (vibrations) through the Earth or other planetary bodies. Seismic waves travel at different speeds and paths through different materials, which reveal the existence of distinct layers. By observing how earthquake-generated seismic waves traveled through the planet, early 20th-century scientists were able to develop a basic model of the Earth’s internal structure.
As seismic techniques and technologies continued to advance, people began to use human-generated seismic waves—often from controlled explosions—to map the geology of the Earth’s crust up to a few kilometers deep. By measuring the properties of these seismic waves, such as how long it took them to return to the surface, reflection seismology could produce accurate maps of subsurface geology, and proved especially useful for locating oil and gas reservoirs.
Why Map the Seafloor?
Though oceans cover more than 70% of Earth’s surface, only about 25% of the seafloor has been mapped in detail. Marine geophysical imaging allows scientists to study the geological processes that shape the ocean floor and our planet, including plate tectonics, sediment deposition and undersea volcanism.
Seismic imaging, especially when combined with data from core samples and boreholes, provides a powerful tool for mapping undersea faults and improving our understanding of subduction zones. These zones, where one tectonic plate slides beneath another, are areas of high seismic activity that can produce large earthquakes and devastating tsunami. By studying the architecture and physical properties of these zones, scientists gain insight into what triggers these dramatic geohazards, enabling better assessments of their potential.
Geophysical imaging is also used to study past sea-level changes by capturing detailed images of sediment layers beneath the seafloor. Analyzing the composition, structure, and layering of these sediments helps scientists understand how sea levels have fluctuated over time due to climate changes and tectonic processes, offering insights into potential future sea-level rise and its impacts. Seismic imaging is also essential for investigating the oceanic crust, which forms most of Earth’s solid surface. This crust is continuously generated at mid-ocean ridges and recycled at subduction zones—processes that drive plate tectonics and shape the Earth’s mantle and crust over geological time.
Another key application of marine seismic imaging is the study of underwater volcanism. It enables scientists to map the magma “plumbing” systems beneath the seafloor, linking the characteristics of deep magma reservoirs to volcanic eruptions. Understanding these connections helps explain why some regions experience frequent volcanic activity while others remain dormant. Undersea volcanic chains are also home to hydrothermal vents, where mineral-rich fluids, heated by volcanic activity, escape from the seafloor. These vents host unique ecosystems and may hold clues to the origins of life on Earth.
As on land, geophysical imaging is also vital to resource exploration at sea. Some areas of the seafloor contain commercially valuable minerals such as copper, nickel and cobalt. Though still a novel and controversial idea, deep-sea mining could one day provide raw materials for electric cars and other industrial applications.
Marine Seismic Imaging Aboard the R/V Langseth
Marine seismic imaging uses seismic waves to create detailed 2D and 3D images of the subsurface geology beneath the ocean.
When surveying, the Langseth tows as many as 40 air guns that release compressed air into the water, generating powerful sound (or seismic) waves. These air guns are “tuned” to produce a more effective and coherent seismic signal, which improves the quality of the subsurface imaging. Deep water geophysical imaging uses low sound frequencies which have longer wavelengths that allow them to travel greater distances through the water column and geological layers with less attenuation (loss of energy). In some cases, these sound waves can reach depths of up to 20-30 kilometers (12-18 miles), allowing for the investigation of the Earth’s deep crust and upper mantle. As the sound waves travel through different layers of the Earth’s subsurface, they are reflected back toward the surface based on the density and composition of the geological formations they encounter.
Arrays of hydrophones—sensitive underwater microphones—are also towed behind the Langseth on cables up to 15 kilometers long called “streamers.” These hydrophones capture the time it takes for the sound waves to return along with their intensity. Finally, the large amounts of collected seismic data are processed by computers that use sophisticated algorithms to create detailed images of the seafloor and subsurface structures.
Seismic Surveying and Marine Animals
Some studies have found that seismic surveying can potentially impact marine animals, particularly those that rely heavily on sound for communication, navigation and hunting, such as whales, dolphins and certain fish species.
To minimize marine-life disturbance, each seismic project conducted by the Langseth undergoes an extensive review process, and Lamont must submit environmental assessments to NOAA National Marine Fisheries Services for evaluation of the project’s potential environmental impacts. Once a project has been approved, the Langseth typically employs five qualified protected species observers (PSOs) on every seismic expedition it undertakes. PSOs actively monitor the survey area both visually and acoustically, and the seismic source is shut down if it is determined that a marine mammal is located within a predefined and permitted perimeter of the vessel. A “soft start” technique may also be used to gradually increase noise levels, allowing animals time to move away from the sound source, and surveys can be timed to avoid sensitive periods for marine animals (e.g., breeding or migration seasons). Such efforts aim to protect marine life while balancing the need for valuable geological data.
The impact of seismic surveys on marine animals remains an active area of research, with both scientists and environmentalists advocating for more in-depth studies.
Learn More
- Cascadia Subduction Zone, One of Earth’s Top Hazards, Comes Into Sharper Focus
- Lamont’s Marie Tharp: She Drew the Maps That Shook the World
- Looking out for Marine Mammals
- Why I Care About the Bottom of the Ocean
- Collecting More Than Just Seismic Data Along the Cascadia Fault
- Life Aboard the Langseth
- Marcus G. Langseth Specifications and Features
- Marine Seismic Imaging: Illuminating Earth’s Structure, Climate, Oceans and Hazards (pdf)
