Stanford University

Geological Sciences Seminar: Larry Mayer, University of New Hampshire – “Ocean Mapping: Exploring the Rest of the Earth”

Tuesday, Feb 19, 2019 12:00 PM
GeoCorner 220 - 450 Serra Mall, Building 320
Faculty/Staff, Students, Alumni/Friends
Department of Geological Science

** Please join us for coffee and cookies in the GeoCorner Undergraduate lounge (bldg. 320, rm 114) before the talk, at 11:30am! - Seminar will be in room 220~

Every field geologist knows that it all starts with a good map. With the evolution of remote sensing techniques, making a detailed map of the earth’s surface has become easier and easier – except for the 71% of Earth’s surface that is covered by water. For thousands of years a weight at the end of a rope provided the only means to measure ocean depth.  By the end of the Second World War, single beam echo sounders had been perfected providing more rapid but laterally averaged measurements of seafloor depths. Towards the end of the 20th Century - two great advances were made in seafloor mapping – the development of techniques to use satellite altimetry to predict seafloor bathymetry and the evolution of multibeam sonar technology.  Satellite-altimetry derived bathymetry provides an unprecedented view of seafloor topography and tremendous insight into tectonic-scale processes but is limited in achievable resolution. Multibeam sonars offer the potential of extremely high-resolution, but are typically deployed from surface vessels that cover a limited amount of seafloor at a relatively high daily cost. High-resolution multibeam sonar data have proven to be tremendously valuable for a range of scientific, military and commercial applications as well as being critical in defining the juridical continental shelf under the Law of the Sea Treaty. In parallel with advances in seafloor mapping, we have also seen exciting new advances in the ability of multibeam and other sonars to image the water column.  Spurred by efforts to trace the deep sea oil plume during Deepwater Horizon, the 3-D imaging of natural and man-made gas plumes is now common, with current work focusing on the acoustic determination of flux rates and the imaging of ocean structure including fine-scale thermohaline steps, internal waves, and the depth of the mixed layer.  To date, however, multibeam sonars have covered less than 10% of the world’s oceans. New technologies like autonomous mapping barges, Saildrones, or sparse arrays, combined with a growing international effort to see the entire seafloor mapped, offer hope that someday we may have a complete map of the seafloor.

Larry Mayer is a Professor and Director of the School of Marine Science and Ocean Engineering and The Center for Coastal and Ocean Mapping at the University of New Hampshire.  He received a Ph.D. from the Scripps Institution of Oceanography in Marine Geophysics in 1979. After being selected as an astronaut candidate finalist for NASA's first class of mission specialists, Larry went on to a Post-Doc at the School of Oceanography at the University of Rhode Island where he worked on the early development of the Chirp Sonar. In 2000 Larry became the founding director of the Center for Coastal and Ocean Mapping at the University of New Hampshire. Larry has participated in more than 90 cruises (over 75 months at sea!) during the last 35 years, and has been chief or co-chief scientist of numerous expeditions including two legs of the Ocean Drilling Program and nine mapping expeditions in the ice-covered regions of the high Arctic. 

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