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TitreInvestigating evidence of paleoearthquakes in lake basin deposits
AuteurBrooks, G R
SourceNuclear Waste Management Organization, Technical Memorandum APM-TM-03720P, 2015, 38 pages
Année2015
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130377
ÉditeurNuclear Waste Management Organization
Documentlivre
Lang.anglais
Mediapapier
Référence reliéeCette publication est remplacée par Brooks, G R; (2015). An integrated stratigraphic approach to investigating evidence of paleoearthquakes in lake deposits of eastern Canada, Geoscience Canada vol. 42 no. 2
Formatspdf
ProvinceQuébec
SNRC21L; 21M; 21N; 22A; 22B; 22C; 22D; 22E; 22F; 22G; 31I; 31J; 31K; 31L; 31M; 31N; 31O; 31P; 32A; 32B; 32C; 32D; 32E; 32F; 32G; 32H
Lat/Long OENS -80.0000 -68.0000 48.0000 45.0000
Lat/Long OENS 7.0000 9.0000 47.5000 46.5000
Sujetsglissements de terrain; dépôts de glissement de terrain; secousses séismiques; études séismiques; sédimentation turbiditique; turbidites; levés acoustiques; analyses stratigraphiques; glissements; stratigraphie; géophysique
Illustrationsprofiles; tables; plots; location maps
ProgrammeRisques géologique du tremblement de terre, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
Seismic shaking can generate mass movement, turbidite, and/or soft sediment deformation deposits within lake basins. These "disturbed" deposits can be preserved and represent a stratigraphic record of paleoearthquakes, as has been demonstrated by numerous studies globally. A pseudo-three-dimensional seismo-stratigraphy of the lake deposits can be constructed from a high density, sub-bottom acoustic profile (SAP) survey, allowing disturbed deposits within the basin to be identified and mapped. "Event layers", which are composed of one or more disturbed deposits at a stratigraphic level, can be identified within the seismo-stratigraphy. Targeted coring of the lake deposits provides ground-truthing of the disturbed deposits. Organic or sediment materials subsampled from the recovered core(s) allow the chronostratigraphy of the lake deposits to be established and ages to be interpreted for the event layers. Maps depicting the distribution, extent and type(s) of disturbed deposit(s) within each event layer can be compiled by integrating the event layer stratigraphy and the three-dimensional architecture of the lake deposits. The occurrence of multiple, synchronous mass movments within a given event layer is a likely signature of significant past earthquake shaking, but possible non-seismic triggers also need to be assessed. A paleoearthquake interpretation can be strongly corroborated where an event layer of given age and of likely seismic origin can be correlated between two or more relatively nearby lake basins. An earthquake catalogue spanning 16 000 years was compiled for central Switzerland primarily from the study of multiple lake basins using the seismo- and chrono-stratigraphic approaches summarized in this report. A comparable earthquake catalogue has not yet been reported from a paleoseismic study of an eastern Canadian lake basin(s). The absence of seismically-induced disturbed deposits in SAP profiles and in recovered core from a well-planned and well-executed investigation of selected lake basins within a given area can contribute to establishing negative evidence of paleoseismicity.
Résumé(Résumé en langage clair et simple, non publié)
Ce rapport résume une méthode pour reconstruire un record de séismes anciens en étudiant la présence de gisements sismique perturbés conservés dans un bassin de lac d'eau douce.
GEOSCAN ID293432