Marine Geophysical Research

, Volume 32, Issue 1–2, pp 25–35 | Cite as

Cautionary considerations for geohazard mapping with multibeam sonar: resolution and the need for the third and fourth dimensions

  • David C. Mosher
Original Research Paper


Most modern submarine geohazard investigations rely heavily on multibeam sonar data, yet there are limitations to these data that must be respected. Disregard of fundamental aspects of spatial sampling, averaging and interpolation, and statistical parameters that accompany all forms of measurement, can lead to over-interpretation of data. Beam spreading and sounding density govern spatial resolution and therefore limit seafloor features that are resolved and interpreted as indicative of geohazards. These resolution limitations are shown with a synthetic model of the seafloor convolved with a spherically spreading wavefront approximated with a spherical smoothing algorithm. This simulation shows the inability to resolve metrics of objects, as well as determine critical parameters such as slope angles with increasing water depth. As well, real case examples are presented showing these effects on identification of targets, slope angles and pockmarks. Misinterpretation of seafloor features is common in multibeam data, particularly without the benefit of coincident subbottom data. Thus it is critical to image the third dimension below the seafloor. Finally, seafloor mapping for geohazards is just one step in a geohazard assessment: it is critical to know frequency of recurrence of geohazard events and their modern geologic context in order to appropriately assess risk.


Multibeam Resolution Marine geohazard Seismic reflection Aliasing 



The author would like to thank F. Chiocci and organizers of the “Seafloor Mapping for Geohazard Assessment” conference for stimulating discussion about this important subject, as well as project MAGIC and IGCP 511 for sponsoring the event. The author’s work and participation in the conference was sponsored by NRCan Earth Science Sector Offshore Geoscience Program. Data for this paper were drawn from many sources and the author would like to thank industry (particularly Encana) and GSC data contributions. P. Fraser was of great assistance in the ArcGIS component of this project. G. Sonnichsen, B. Todd and J. Shaw reviewed the paper prior to publication and I thank the two anonymous reviewers and the editors who supplied helpful comments to greatly improve the manuscript. Natural Resources Canada, Earth Science Sector contribution number 20100123.


  1. Bjørke JT, Hæger M, Landmark K, Nilsen S (2007) A concept for creating, storing, updating and delivering variable resolution terrain models. Proc ScanGIS 2007:15–26Google Scholar
  2. de Moustier C (2001) Field evaluation of sounding accuracy in deep water multibeam swath bathymetry. IEEE Oceans Conference and Exhibition Proc, vol 3. Honolulu, Hawaii, pp 1761–1765Google Scholar
  3. Deptuck ME, Mosher DC, Campbell DC, Hughes-Clarke JE, Noseworthy D (2007) Along slope variations in mass failures and relationships to major Plio-Pleistocene morphological elements, SW Labrador Sea. In: Lykousis V, Dimitris S, Locat J (eds) Submarine mass movements and their consequences, vol III. Springer, The Netherlands, pp 37–46CrossRefGoogle Scholar
  4. Hughes Clarke JE, Gardner JV, Torresan M, Mayer L (1998) The limits of spatial resolution achievable using a 30kHz multibeam sonar: model predictions and field results: IEEE oceans 98. Proc 3:1823–1827Google Scholar
  5. Morgan J, Silver E, Camerlenghi A, Dugan B, Kirby S, Shipp C, Suyehiro K, Krye K (2008) Addressing geologic hazards through ocean drilling, unpublished report from an IODP international workshop, August 26–30, 2007. Portland, Oregon, p 40Google Scholar
  6. Mosher DC and Campbell DC (in press) The Barrington submarine landslide, western Scotian Slope. In: Shipp C, Weimer P and Posamentier H (eds) The importance of mass-transport deposits in deepwater settings. SEPM Spec Pub 91Google Scholar
  7. Mosher DC and Donda F (2009) CCGS Hudson 2008-027 Expedition report: labrador sea margin, Geol Surv Can Open File 5941, 1 DVDGoogle Scholar
  8. Mosher DC, Piper DJW (2007) Analysis of multibeam seafloor imagery of the Laurentian Fan and the 1929 Grand Banks landslide area. In: Lykousis V, Dimitris S, Locat J (eds) Submarine mass movements and their consequences. Springer, The Netherlands, pp 77–88CrossRefGoogle Scholar
  9. Mosher DC, Moran KM, Hiscott RN (1994) Late quaternary sediment, sediment mass-flow processes and slope instability on the Scotian Slope. Sedimentol 41:1039–1061CrossRefGoogle Scholar
  10. Mosher DC, Piper DJW, Campbell DC, Jenner KA (2004) Near surface geology and sediment failure geohazards of the central Scotian Slope. Am Assoc Pet Geol Bull 88:703–723Google Scholar
  11. Mosher DC, Bigg S, LaPierre A (2006) 3D seismic versus multibeam sonar seafloor surface renderings for geohazard assessment: case examples from the central Scotian slope. Lead Edge 25:1484–1494CrossRefGoogle Scholar
  12. Pâquet R 2010 Estimation of interpolation error in DEMs using statistical methods fig congress 2010: facing the challenges—building the capacity, Sydney, Australia, 11–16 April 2010. Accessed 30 August, 2010
  13. Pickrill RA 2007 Implementing Canada’s national marine mapping strategy. In: The 2007 US hydrographic conference technical papers, May 15–17, 2007, Norfolk, Virginia. Accessed 1 May 2010
  14. Piper DJW Campbell DC Loloi M Tripsanas E Mosher DC Benetti S (2004) Sediment instability in Orphan Basin, offshore eastern Canada. 57th Canadian Geotech Conf, Quebec, October 23–27, extended abstractsGoogle Scholar
  15. Piper DJW Shor AN Hughes Clarke JE (1988) The 1929 Grand Banks earthquake, slump and turbidity current. In: Clifton HE (ed) Sedimentologic consequences of convulsive geologic events. Geol Soc Am Spec Paper 229: 77–92Google Scholar
  16. Piper DJW, Mosher DC, Gauley B-J, Jenner K, Campbell DC (2003) The chronology and recurrence of submarine mass movements on the continental slope off southeastern Canada. In: Locat J, Mienert J (eds) Submarine mass movements and their consequences, vol I. Kluwer Publ, The Netherlands, pp 299–306CrossRefGoogle Scholar
  17. Rocchesso D Polotti P (2008) Signal processing in processing: sampling and quantization. Connexions, June 5, 2008, Accessed 28 April 2010
  18. Sibson R (1981) A brief description of natural neighbor interpolation, chapter 2 in interpolating multivariate data, John Wiley & Sons, New York, 21–36Google Scholar
  19. Sonnichsen GV Breton C Carr E Campbell P King T (2009) Repetitive seabed mapping to constrain iceberg scour frequency estimates, offshore Labrador. Proc 20th Int Conf on Port and Ocean Engineer under Arctic conditions, 9–12 June, 2009, Luleà, SwedenGoogle Scholar
  20. Sonnichsen GV Lamplugh M (2008) Seabed mapping surveys, SW Makkovik Bank, Harrison Bank, NRCAN expedition report 2008028 Geol Surv Can Open File 5931, pp 26Google Scholar
  21. Tripsanas EK, Piper DJW (2008) Glaciogenic debris-flow deposits of Orphan Basin, offshore eastern Canada: sedimentological and rheological properties, origin, and relationship to meltwater discharge. J Sediment Res 78:724–744CrossRefGoogle Scholar
  22. Watson DF, Philip GM (1985) A refinement of inverse distance weighted interpolation. Geoprocessing 2:315–327Google Scholar
  23. White DR, Saunders P (2000) The propagation of uncertainty on interpolated scales, with examples from thermometry. Metrologia 37:285. doi: 10.1088/0026-1394/37/4/4 CrossRefGoogle Scholar

Copyright information

© Her Majesty the Queen in Right of Canada 2010

Authors and Affiliations

  1. 1.Natural Resources Canada, Geological Survey of Canada—AtlanticBedford Institute of OceanographyDartmouthCanada

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