A global study of swath bathymetry data and the depth of the seafloor
with time
M. Paulatto and A. B. Watts
Technological advances in shipboard navigation and swath bathymetry systems have
made it possible to measure the depth of the ocean floor to accuracies of better than 1-2
m, even in water depths > 2 km. Since 1992, there have been >500 swath bathymetry
research cruises that have insonified ~6% of the ocean floor (see Figure for the
distribution of swath cruises in the eastern Pacific Ocean). The bathymetric grids
constructed using this data have provided new information on the role that submarine
volcanism, tectonics, mass wasting and sediment transport have played in shaping the
ocean floor. Yet, there have been few studies of repeat swath surveys where data from
one cruise overlaps that of another. Recently, we compared swath data acquired over the
Monowai submarine volcano (southwest Pacific Ocean) in 1998, 2004, 2007 and 2011
and found dramatic differences in the depth of the seafloor between the surveys of up to
+135 m and –70 m. Within one cruise alone, we found positive differences of +70 m and
negative differences of up -18 m that indicate growth and collapse of the volcano on
time-scales as short as a few days. In this project, the student will use a global swath
bathymetry data set to determine those regions of the seafloor that are deforming and
those that are stable. Where possible the swath data will be compared to single beam
(echo-sounder) data, especially data acquired since 1967 which marks the transition from
celestial to satellite navigation. The aim of the project is to identify and record seafloor
depth variations within the global swath data set and to examine its implications for
seafloor processes. The project will involve the manipulation of large shipboard
bathymetric data sets and the analysis of these data using Google Earth, GeoMapApp and
GMT software tools. The project should appeal to students interested in working at the
boundaries of geology and geophysics on a topic that is central to current efforts to
understand the shape of the seafloor, its geology and its implications for global and
environmental change.
Selected references:
Hillier, J. K., and A. B. Watts (2007), Global distribution of seamounts from ship-track
bathymetry data, Geophys. Res. Letts., 34, doi:10.1029/2007GL029874. PDF
Wessel, P. (2001), Global distribution of seamounts inferred from gridded Geosat/ERS-1
altimetry, J. Geophys. Res., 10.1029/2000JB000083.
Ryan, W. B. F., S. M. Carbotte, J. O. Coplan et al. (2009), Global multi-resolution topography
synthesis, Geochemistry, Geophysics, Geosystems, doi:10.1029/2008GC002332
Watts, A. B., D. T. Sandwell, W. H. F. Smith, and P. Wessel (2006), Global gravity, bathymetry,
and the distribution of submarine volcanism through space and time, J. Geophys. Res.,
111, doi:10.1029/2005JB004083. PDF
Watts, A. B., C. Peirce, I. Grevemeyer, M. Paullato, W. Stratford, D. Bassett et al. (submitted),
Rapid rates of collapse and growth at the Monowai submarine volcano, Kermadec arc.