| Titre | Preliminary evidence of Late Quaternary faulting in the Rocky Mountain Trench from new LiDAR data and field investigations |
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| Auteur | Finley, T; Prush, V; Nissen, E; Miller, B; Sethanant, I; Cassidy, J ; Rowe, C D |
| Source | American Geophysical Union Fall Meeting 2021, abstracts; T54A-09, 2021 p. 1  Accès ouvert |
| Liens | Online - En ligne
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| Image |  |
| Année | 2021 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20210335 |
| Éditeur | American Geophysical Union |
| Réunion | American Geophysical Union Fall Meeting 2021; New Orleans, LA; US; décembre 13-17, 2021 |
| Document | site Web |
| Lang. | anglais |
| Media | numérique; en ligne |
| Formats | html; pdf |
| Province | Colombie-Britannique; Yukon; Alberta |
| SNRC | 72; 82; 83; 84; 92; 93; 94; 95; 104; 105; 106; 115; 116 |
| Région | Alaska |
| Lat/Long OENS | -145.0000 -110.0000 65.0000 49.0000 |
| Sujets | Holocène; Paléogène; Eocene; levés géophysiques; géologie du substratum rocheux; caractéristiques structurales; fosses; failles normales; failles, décrochement; antécédents tectoniques; déplacement;
risque sismique; sismicité; secousses séismiques; risque de tremblement de terre; rapports sur le terrain; interprétations géophysiques; topographie; escarpements; sediments; structures sédimentaires; Cordillère canadienne; Infrastructure; géologie
structurale; géophysique; tectonique; géologie des dépôts meubles/géomorphologie; Sciences et technologie; Nature et environnement; Santé et sécurité; Phanérozoïque; Cénozoïque; Quaternaire; Tertiaire |
| Programme | Géoscience pour la sécurité publique Risques géologique du tremblement de terre |
| Diffusé | 2021 12 01 |
| Résumé | (disponible en anglais seulement)
The Rocky Mountain Trench (RMT) is a ~1500 km-long valley that stretches from northern Montana through the eastern Canadian Cordillera of British Columbia (BC)
to the Yukon border, where it continues another 1000 km to Alaska as the Tintina Trench. A series of major faults occupy the RMT for much of its length. Faults that define the Southern RMT have accommodated ~5-10 kilometers of normal displacement,
while faults along the Northern RMT are thought to have accommodated ~450 km of dextral displacement. Despite the RMT's remarkably linear topographic expression, these faults are generally believed to be Eocene in age, not Holocene. Here we evaluate
the neotectonics and seismic hazard of the RMT based on new lidar data, field investigations, and existing geophysical evidence. We undertook a systematic review of the lidar data and found that while young surface ruptures are not pervasive in the
RMT, there are several features of possible neotectonic origin, including fault scarps, sackungen, and river channel offsets. We conducted preliminary fieldwork at several of these sites and found evidence of tectonic deformation in Late Quaternary
sediments filling the RMT. In some cases, faults cross-cutting these sediments are not associated with continuous scarps on the surface, highlighting a challenge of paleoseismic work in this environment where dynamic post-glacial (post-13 kya)
geomorphic processes may have erased the surface expression of Holocene faults. Detailed mapping and geochronology of glacial sediments and their cross-cutting relations will be necessary to confirm the occurrence and age of past earthquakes. Our
observations add to existing evidence of neotectonic activity on the RMT: several poorly located historical earthquakes of M 4-6 have occurred in the vicinity of the RMT and may in fact have occurred along it; local seismograph networks have detected
small earthquakes along some segments; and geodetic networks - though sparse - indicate a minor strain gradient across the eastern Cordillera, which may be localized on the RMT faults. Collectively, ~135,000 people live along the RMT, and several
major highways, freight railways, hydroelectric dams, and oil and gas pipelines lie within or cross the valley. It is therefore critical that further work is carried out to understand the seismic hazard of the RMT. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Le but de cette recherche est de rechercher des preuves de failles le long d'anciennes failles en Colombie-Britannique, en particulier le sillon
des montagnes Rocheuses et les structures associées. Ce travail utilise des preuves géophysiques existantes, de nouvelles données lidar et des enquêtes sur le terrain. Cette étude a révélé plusieurs caractéristiques de failles sismiques possibles,
notamment des escarpements, des sackungen et des décalages de canaux fluviaux décalés. Ces résultats aideront à orienter les futures études détaillées qui contribueront à une meilleure évaluation des risques sismiques dans cette région. |
| GEOSCAN ID | 328999 |
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