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TitlePaleoseismicity of the continental margin of eastern Canada: rare regional failures and associated turbidites in Orphan Basin
AuthorPiper, D J WORCID logo; Tripsanas, E; Mosher, D CORCID logo; McKillop, K
SourceExploring the deep sea and beyond: contributions to marine geology in honor of William R. Normark; by Fildani, A (ed.); Geosphere vol. 15, no. 1, 2018 p. 1-23, Open Access logo Open Access
Alt SeriesEarth Sciences Sector, Contribution Series 20100367
PublisherGeological Society of America
Mediaon-line; digital
File formatpdf (Adobe® Reader®); docx (Microsoft® Word®)
ProvinceNewfoundland and Labrador; Eastern offshore region
AreaAtlantic Ocean; Orphan Basin
Lat/Long WENS -51.7500 -45.5000 51.0000 47.5000
Subjectsmarine geology; surficial geology/geomorphology; geophysics; sedimentology; tectonics; stratigraphy; engineering geology; continental margins; continental slope; seismic risk; seismicity; earthquakes; earthquake risk; earthquake magnitudes; landslides; slope failures; landslide deposits; debris flow deposits; marine sediments; turbidites; glacial deposits; marine sediment cores; geophysical surveys; seismic surveys, marine; seismic reflection surveys; seismic profiles; models; geological history; tectonic history; sedimentation rates; glacial history; tectonic setting; lineaments; lithostratigraphy; stratigraphic correlations; slope stability analyses; bulk density determinations; shear strength; shear stress; grain size distribution; Heinrich Layers; Charlie-gibbs Fracture Zone; Cumberland Belt; Last Glacial Maximum (Lgm); Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; geoscientific sketch maps; correlation sections; seismic profiles; profiles; tables; lithologic sections; photographs; frequency distribution diagrams; stratigraphic columns; bar graphs; histograms; plots
ProgramOffshore Geoscience
Released2018 12 20
AbstractThe eastern Canadian continental margin is a typical glaciated passive margin where historic earthquakes have triggered submarine landslides. This study compares seismological estimates of earthquake recurrence with the geological record over the past 85 k.y. offshore of Newfoundland to assess the reliability of the geologic record. Heinrich layers in cores provide chronology at ~3-5 k.y. resolution in high-resolution seismic-reflection profiles across headscarps and mass-transport deposits. Landslide-generated turbidites on the basin floor have distinctive petrology, sedimentology, and distribution, with ~1 k.y. chronologic resolution. Large slope failures occurred synchronously over margin lengths of 50-300 km. Since 85 ka, four failures have affected a >150-km-long sector of the slope and 18 failures were large enough to be recognized in seismic-reflection profiles and/or cores. The widespread failures were earthquake triggered; other mechanisms for triggering laterally extensive synchronous failure do not apply. A frequency-magnitude plot of length of failed slope was calibrated by the published relationship that an order-of-magnitude increase in failed slope length corresponds to two orders of magnitude of earthquake energy, together with the published estimate of Mw = 8.0 for the largest earthquake on the Canadian eastern continental margin. Mean recurrence interval of M = 7 earthquakes at any point on the margin is estimated at 25-30 k.y. from both seismological models and the sediment failure record. On such a margin with modest sedimentation rates (~0.3 m/k.y.) and low seismicity, sediment failures provide a robust estimator of past seismicity.

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