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TitleActive transcurrent faulting within the Cascadia upper plate that extends across the US (Washington)-Canada international border
AuthorGreene, H G; Barrie, V; Todd, B
SourceResources for Future Generations, 16-21 June 2018, Vancouver, British Columbia, Canada, International Union of Geological Sciences, abstract volume; 1510, 2018 p. 1
Year2018
Alt SeriesNatural Resources Canada, Contribution Series 20170320
PublisherInternational Union of Geological Sciences
MeetingRFG 2018 - Resources for Future Generations; Vancouver, BC; CA; 16-21 June 2018
Documentbook
Lang.English
Mediaon-line; digital
File formatpdf
ProvinceBritish Columbia; Western offshore region
NTS92B; 92G/01; 92G/02; 92G/03; 92G/04; 92G/05; 92G/06; 92G/07; 92G/08
AreaVancouver Island; Victoria; Vancouver; Fraser River Delta; Washington State; San Juan Archipelago; Orcas Island; Bellingham; Canada; United States
Lat/Long WENS-124.0000 -122.0000 49.5000 48.0000
Subjectsmarine geology; tectonics; structural geology; surficial geology/geomorphology; geophysics; plate margins; plate motions; bedrock geology; structural features; faults, transcurrent; submarine features; landslides; mass wasting; geophysical surveys; geophysical interpretations; acoustic surveys, marine; seismic surveys, marine; seismic profiles, marine; seismic reflection surveys; core samples; marine sediments; seismicity; earthquakes; seismic risk; earthquake risk; tsunami; Cascadia Subduction Zone; Devils Mountain Fault Zone; Skipjack Island Fault Zone; geological hazards; multibeam bathymetry; Phanerozoic; Cenozoic; Quaternary
ProgramAssessing Earthquake Geohazards, Public Safety Geoscience
Released2018 06 01
AbstractMarine geohazards mapping of the northern upper plate of the Cascadia subduction complex within the San Juan Archipelago has been jointly undertaken by the Geological Survey of Canada, Research NW, and Moss Landing Marine Labs' Tombolo Mapping Lab on Orcas Island, Washington. Identification of active faults that cross the Canada-US international boundaries and submarine slides were mapped in detail with new faults and slides being imaged using multibeam echosounder (MBES) bathymetric data, Huntec and 3.5-kHz seismic-reflection profiles, and gravity cores. Two across-forearc fault zones, the Devils Mountain and the newly discovered Skipjack Island fault zones, bracket the San Juan Archipelago, extending from Washington, USA to Vancouver Island, BC Canada. These fault zones intersect and displace Quaternary sediments and extend close to the cities of Bellingham, WA and Victoria, BC. The seismic potential of these faults not only increases the seismic hazards for these urban centers, but could stimulate mass wasting along NE Orcas Island and the southern front of the Fraser River Delta near Vancouver, BC, thus producing locally generated tsunamis. In addition, parts of the San Juan Archipelago appear to have undergone rotation within the upper plate, the result of strike-slip movement on the Skipjack Island fault zone.
Summary(Plain Language Summary, not published)
Identification of active faults that cross the Canada-US international boundaries and submarine slides were mapped in detail with new faults and slides being imaged. Two fault zones, the Devils Mountain and the newly discovered Skipjack Island fault zones, bracket the San Juan Archipelago, extending from Washington, USA to Vancouver Island, BC Canada. These fault zones intersect and displace Quaternary sediments and extend close to the cities of Bellingham, WA and Victoria, BC. The seismic potential of these faults increases the seismic hazards for these urban centres. The faults could stimulate mass wasting along NE Orcas Island and the southern front of the Fraser River Delta near Vancouver, BC, thus producing locally generated tsunamis.
GEOSCAN ID306413