R/V Langseth

Research Vessel Marcus G. Langseth
 

"There is, one knows not what sweet mystery about this sea, whose gently awful stirrings seem to speak of some hidden soul beneath." - Herman Melville

The ocean is Earth's last frontier, with its depths hidden from human eyes. But in the deep, where sunlight cannot penetrate, sound can substitute for human vision. Working to uncover the dynamics of the deep seafloor, the Research Vessel Marcus G. Langseth employs sophisticated seismic systems that use sound to create images. As the Lamont-Doherty Earth Observatory and the National Science Foundation prepare to welcome a new decade of research on the Langseth, plans are in development to further enhance the ship's research capabilities. Coming years will see the Langseth continue to enable groundbreaking seismic research while maximizing its research potential by supporting a broader spectrum of ocean-research activities.

A Multidimensional Research Platform

The Langseth offers unparalleled opportunities for scientists interested in pursuing research in the fields of marine geophysics, seismology and general oceanography. Purchased in 2004 by Columbia University under a cooperative agreement with the National Science Foundation, the 71.5-meter vessel is operated by the Lamont-Doherty Earth Observatory, a historic pioneer in seismological studies. The ship performs the many tasks required of a general-purpose research vessel; it has 3.5- and 12-kilohertz transducers for sub-bottom profiling and bathymetric mapping, a deep-ocean Kongsberg EM122 (1x1 array) multibeam sonar system capable of mapping swaths of the ocean floor up to five times the water depth at high resolution, and a flow-through uncontaminated salt water system used to monitor the chemical content of the surrounding ocean water. As the Langseth navigates the oceans, the vessel continuously records data pertaining to meteorology, magnetics, gravity and carbon dioxide concentrations. It offers researchers the use of 425 square meters of on-board laboratory space.

The ship's advanced multichannel seismic system, a Syntrak 960-24 recording system, can be configured as a single hydrophone array up to eight kilometers long for two-dimensional multichannel imaging or as four six-kilometer arrays for three-dimensional multichannel imaging. Four linear sound arrays equipped with ten pneumatic sound sources are tuned to generate signals with peak energy between two and 210 hertz that propagate up to 10 kilometers below the ocean floor and reflect off of sub-seafloor structures. The ship's hydrophone arrays receive, record and digitize the reflected seismic waves. GPS receivers, acoustic networks and compasses work in harmony to calculate the precise location of sub- seafloor structures. The data are then processed into high-quality two-dimensional images or three-dimensional seismic volumes that depict the sub-seafloor structure.

Sub-Seafloor Imaging Techniques

Scientists onboard the Langseth are responsible for many invaluable contributions to humankind's knowledge of Earth's sub-seafloor. On the Langseth in 2008, a five-person team of researchers from the Lamont-Doherty Earth Observatory, Woods Hole Oceanographic Institution and Dalhousie University led the first multi-streamer, three-dimensional seismic acquisition program carried out solely by an academic vessel. The result was a three- dimensional image of an erupting portion of the global mid-ocean ridge near 9°50'N on the East Pacific Rise with a resolution, geometric accuracy and scale comparable to that of most direct seafloor mapping (Geochemistry, Geophysics, Geosystems, October 2008). Thanks to the three-dimensional multichannel seismic technique used on the Langseth, scientists now resolve and map structures that were once impossible to observe. Researchers can image the fine-scale internal architecture of rifted-margin-related volcanic events, which are among the largest volcanic eruptions on the planet but are seldom visible from shore.

The Langseth offers an ideal research platform for imaging the seismic structure of subduction zones; the vessel will spend the summer of 2011 researching the northernmost section of the Pacific Ring of Fire, specifically a subduction zone off the Alaskan coast. The Ring of Fire is responsible for some of the largest earthquakes and tsunamis ever recorded; studies such as these can significantly improve scientific understanding of the origins of devastating natural disasters. Seismic observation advances our knowledge of Earth's geological history, natural hazard potential and climate systems. The sum result of the Langseth's observations is an essential contribution to fundamental knowledge of marine geology and geophysics and general oceanography.

Prioritizing Wildlife

The Langseth follows strict protocols and uses advanced technology to minimize interactions between acoustic sources and animals. Extensive environmental analysis is done to avoid the scheduling of seismic research in areas where migration, breeding or calving of marine mammals is taking place. In order to increase the certainty that marine animals are outside a designated radius — calculated by computer models to predict where sound pulses would be received at high-decibel levels — protected species observers visually scan the ocean with high-power binoculars and use hydrophone streamers to listen for nearby marine mammal vocalizations. The seismic source is activated slowly, with volume increasing incrementally. For the sake of protected species, the Langseth's crew is always prepared to reduce or shut down the seismic sound source, based on recommendations from trained, on-board protected species observers.

A New Era for Ocean Science

Researchers aboard the Langseth enjoy unparalleled opportunities to produce groundbreaking research. Looking forward, plans for an expansion of the vessel's multipurpose capabilities are now underway. Lamont-Doherty Earth Observatory's Office of Marine Operations is actively working with naval architects to implement a plan for winch installation and deck- space utilization in order to maximize the Langseth's ability to conduct a broad spectrum of ocean-research activities. The Lamont-Doherty Earth Observatory and the National Science Foundation look forward to inviting scientists aboard the Research Vessel Marcus G. Langseth for an exciting new era of research.

To learn more about the Langseth's capabilities, please visit the Office of Marine Operations Web site at www.ldeo.columbia.edu/research/office-of-marine-operations.

To learn more about submitting proposals for research on board the Langseth, please visit the NSF proposals Web site at www.nsf.gov/publications/pub_summ.jsp?ods_key=papp or http://www.nsf.gov/funding/pgm_list.jsp?org=GEO.