caa a22 4500 445364939 CHVBK 20180317142927.0 cr unu---uuuuu 170323e20110301xx s 000 0 eng 10.1007/s11001-010-9104-y doi (NATIONALLICENCE)springer-10.1007/s11001-010-9104-y Mosher David Natural Resources Canada, Geological Survey of Canada—Atlantic, Bedford Institute of Oceanography, 1 Challenger Dr., B2Y 4A2, Dartmouth, Nova Scotia, Canada aut Cautionary considerations for geohazard mapping with multibeam sonar: resolution and the need for the third and fourth dimensions [Elektronische Daten] [David Mosher] 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. Her Majesty the Queen in Right of Canada, 2010 Multibeam nationallicence Resolution nationallicence Marine geohazard nationallicence Seismic reflection nationallicence Aliasing nationallicence Marine Geophysical Research Springer Netherlands 32/1-2(2011-03-01), 25-35 0025-3235 32:1-2<25 2011 32 11001 https://doi.org/10.1007/s11001-010-9104-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11001-010-9104-y text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Mosher David Natural Resources Canada, Geological Survey of Canada—Atlantic, Bedford Institute of Oceanography, 1 Challenger Dr., B2Y 4A2, Dartmouth, Nova Scotia, Canada aut NATIONALLICENCE 773 0- Marine Geophysical Research Springer Netherlands 32/1-2(2011-03-01), 25-35 0025-3235 32:1-2<25 2011 32 11001 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer