| Title | Preliminary investigations of unconsolidated sediments overlying the Leech River fault zone, southern Vancouver Island, British Columbia |
| Download | Downloads |
| Author | Bednarski, J M |
| Source | Geological Survey of Canada, Open File 8046, 2016, 29 pages, https://doi.org/10.4095/298809 (Open Access) |
| Year | 2016 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| File format | readme
|
| File format | rtf; pdf; kmz |
| Province | British Columbia |
| NTS | 92B/05NE; 92B/05NW; 92B/06NE; 92B/06NW; 92B/11; 92B/12; 92B/13; 92B/14; 92C/08; 92C/09 |
| Area | Vancouver Island; Leech River; Jack Lake; Esquimalt |
| Lat/Long WENS | -124.5000 -123.1667 49.0000 48.4500 |
| Subjects | geophysics; surficial geology/geomorphology; structural geology; faults; fault zones; seismicity; seismic interpretations; slope stability; slope stability analyses; landslides; remote sensing; terrain
sensitivity; terrain types; terrain analysis; LIDAR; Leech River Fault; digital elevation models |
| Illustrations | location maps; photographs; tables; profiles |
| Program | Western Canada Geohazards Project, Public Safety Geoscience |
| Released | 2016 06 28 |
| Abstract | The Leech River fault zone lies near the city of Victoria, British Columbia. Although this fault zone has been considered to be inactive for millions of years, two large paleo-earthquakes have been
identified on its eastern extension, only 40 km from the city. Confirmation of an active fault in proximity to an urban centre or a part of critical infrastructure would fundamentally change the analysis of seismic hazard. To determine the occurrence
of more recent faulting, younger sediments overlying the faulted bedrock were surveyed by high resolution Lidar topography, ground penetrating radar, electrical resistivity, and shallow seismic reflection lines. Targeted areas included surface scarps
and transects crossing the bedrock structure in search of disturbed sediment that may be attributed to recent faulting. Preliminary results do not find conclusive evidence of active faulting in the youngest sediment dating from postglacial time, at
least in the upper 5 to 10 m; however, the seismic reflection survey found deeper, faulted deposits dating from at least the last glaciation and warrant further investigation. |
| Summary | (Plain Language Summary, not published)
The Leech River fault zone lies near the city of Victoria, British Columbia. Although this fault zone is considered to be inactive for millions of years,
confirmation of an active fault in proximity to an urban center or critical infrastructure would fundamentally change the analysis of seismic hazard. To determine the possibility of more recent faulting, younger sediments overlying the fault zone
were surveyed by high-resolution topography, ground penetrating radar, electrical resistivity and seismic reflection lines. Targeted areas included surface scarps and transects crossing the bedrock structure in search of disturbed sediment that may
be attributed to recent faulting. Preliminary results do not find conclusive evidence of any faulting in the youngest sediment (dating from postglacial time), however, the seismic survey found faults through deeper deposits dating from at least the
last glaciation, which warrant further investigation. |
| GEOSCAN ID | 298809 |
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