Shallow gas hazards in Queen Charlotte Basin from interpretation of high resolution seismic and multibeam data

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dc.contributor.authorHalliday, Julie
dc.contributor.supervisorChapman, N. R.
dc.contributor.supervisorBarrie, J. V.
dc.date.accessioned2008-12-30T19:17:35Z
dc.date.available2008-12-30T19:17:35Z
dc.date.copyright2008en_US
dc.date.issued2008-12-30T19:17:35Z
dc.degree.departmentSchool of Earth and Ocean Sciencesen_US
dc.degree.levelDoctor of Philosophy Ph.D.en_US
dc.description.abstractThis thesis investigates shallow gas hazards in Queen Charlotte Basin, a sedimentary basin situated offshore British Columbia. The work presented here provides the first detailed gas hazard assessment in Queen Charlotte Basin and the first evidence that gas has migrated from basin sediments into surficial sediments to be expelled in the water column. A unique method of geophysical surveying is used to investigate hazards due to shallow gas at two sites within Queen Charlotte Basin: high-resolution multichannel seismic, Huntec Deep-Towed Seismic and multibeam bathymetry data were collected over two 2-D grids and interpreted concurrently to yield a comprehensive understanding of the geology at each site. Numerous features related to both ice-cover and shallow gas has been identified. Pockmarks, iceberg ploughmarks and seafloor mounds are observed in the multibeam data; acoustically turbid and vertical blank zones are imaged in the Huntec data and faulted anticlines containing bright spots as well as low frequency shadow zones are seen in the multichannel data. Combining and interpreting all three geophysical datasets concurrently provided the means to discriminate features related to ice-cover from features related to gas in the shallow sediments. In addition, this method of geohazards assessment has enabled links between surficial and basin geology to be made. Based on the results obtained gas and other geohazards were identified at each of the two sites. Based on observations in high-resolution multichannel seismic data, gas is determined to have migrated along structural pathways within basin sediments and into surficial sediments. The level of hazard posed by shallow gas has been assessed qualitatively for each of the two study sites and gas hazard regions have been identified elsewhere in Queen Charlotte Basin.en_US
dc.identifier.urihttp://hdl.handle.net/1828/1312
dc.languageEnglisheng
dc.language.isoenen_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectshallow gasen_US
dc.subjectpockmarksen_US
dc.subjectmoundsen_US
dc.subjectshallow faultsen_US
dc.subjectglaciated marginen_US
dc.subjectmultichannel seismicen_US
dc.subjectmultibeamen_US
dc.subjectHuntec DTSen_US
dc.subjectploughmarksen_US
dc.subjectgeohazardsen_US
dc.subject.lcshUVic Subject Index::Sciences and Engineering::Earth and Ocean Sciences::Geophysicsen_US
dc.subject.lcshUVic Subject Index::Sciences and Engineering::Earth and Ocean Sciences::Geologyen_US
dc.titleShallow gas hazards in Queen Charlotte Basin from interpretation of high resolution seismic and multibeam dataen_US
dc.typeThesisen_US

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