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Acoustic characterization of submarine geomorphological features in the Polar Oceans
Stockholm University, Faculty of Science, Department of Geological Sciences.
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Marine glacial environments contain unique seafloor features resulting from the dynamic glacial processes. Studying these submarine geomorphological features can help us understand the glacial paleo-environments so that we can predict the likely responses of present day glaciers and ice sheets to future changes in the climate. This thesis details different approaches in understanding glacial seafloor features using acoustic systems. It focuses on the novel technique of automated mapping seafloor properties using the backscatter intensity collected by acoustic multibeam echosounder systems (MBES). The aim of this thesis is to assess the potential of this unexploited data source in characterizing different glacial landforms in the polar oceans. This is done by examining the voluminous backscatter data collected by Swedish icebreaker Oden from different cruises to the polar oceans and employing an automated backscatter processing technique, the ARA algorithm, to extract surficial sediment characteristics. The results from the sediment characterization are used together with outputs from other marine acoustical systems and sediment core data to understand formational processes of the glacial submarine features. Operational issues encountered in using this technology and its viability as a tool in characterization of glacial seafloor features are discussed and suggestions are given on the improvements needed to effectively implement the method in future studies. The final part of the manuscript is a paper, published in Geo-marine Letters, where I and my co-authors show a practical application of the acoustic systems ability to characterize geomorphological features of a mass-wasting event in the deepest part of the Arctic, the Molloy Hole. 

Place, publisher, year, edition, pages
Stockholm: Department of Geological Sciences, Stockholm University , 2014. , 37 p.
National Category
URN: urn:nbn:se:su:diva-103370OAI: diva2:716819
Available from: 2015-01-15 Created: 2014-05-12 Last updated: 2016-02-23Bibliographically approved
List of papers
1. Acoustic evidence of a submarine slide in the deepest part of the Arctic, the Molloy Hole
Open this publication in new window or tab >>Acoustic evidence of a submarine slide in the deepest part of the Arctic, the Molloy Hole
2014 (English)In: Geo-Marine Letters, ISSN 0276-0460, E-ISSN 1432-1157, Vol. 34, no 4, 315-325 p.Article in journal (Refereed) Published
Abstract [en]

The western Svalbard continental margin contains thick sediment sequences with areas known to contain gas hydrates. Together with a dynamic tectonic environment, this makes the region prone to submarine slides. This paper presents results from geophysical mapping of the deepest part of the high Arctic environment, the Molloy Hole. The mapping includes multibeam bathymetry, acoustic backscatter and sub-bottom profiling. The geophysical data reveal seabed features indicative of sediment transport and larger-scale mass wasting. The large slide scar is here referred to as the Molloy Slide. It is located adjacent to the prominent Molloy Hole and Ridge system. The slide is estimated to have transported >65 km(3) of sediments over the deep axial valley of the Molloy Ridge, and further into the Molloy Hole. A unique feature of this slide is that, although its run-out distance is relatively short (<5 km), it extends over an enormous vertical depth (>2,000 m) as a result of its position in a complex bathymetric setting. The slide was most likely triggered by seismic activity caused by seafloor spreading processes along the adjacent Molloy Ridge. However, gas-hydrate destabilization may also have played a role in the ensuing slide event.

National Category
Earth and Related Environmental Sciences
Research subject
Marine Geology
urn:nbn:se:su:diva-108215 (URN)10.1007/s00367-014-0371-5 (DOI)000341828100002 ()


Available from: 2014-10-15 Created: 2014-10-15 Last updated: 2016-02-26Bibliographically approved

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