Holocene surface rupture history of an active forearc fault redefines seismic hazard in Southwestern British Columbia, Canada
Geophysical Research Letters
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Abstract
Characterizing the hazard associated with Quaternary‐active faults in the forearc crust of the northern Cascadia subduction zone has proven challenging due to historically low rates of seismicity, late Quaternary glacial scouring, and dense vegetation that often obscures fault‐related geomorphic features. We couple lidar topography with paleoseismic trenching across the Leech River Fault on southern Vancouver Island to produce the first detailed surface rupture history of an onland forearc fault in British Columbia, Canada. The results indicate that this fault produced three surface‐rupturing earthquakes in the last ∼9 kyr and is therefore capable of producing large (Mw>6) earthquakes in the future. We provide new constraints on the fault's length (∼130 km) and Holocene slip rate (≥0.2–0.3 mm/year) that, together with the earthquake ages, should be incorporated into new seismic hazard assessments and building code practices relevant to urban centers in southwestern British Columbia (Canada) and northwestern Washington State (United States).
Suggested Citation
Morell, K.D., Regalla, C., Amos, C., Bennett, S., Leonard, L., Graham, A., Reedy, T., Levson, V., and Telka, A., 2019, Holocene surface rupture history of an active forearc fault redefines seismic hazard in Southwestern British Columbia, Canada: Geophysical Research Letters, v. 45, no. 21, p. 11605-11611, https://doi.org/10.1029/2018GL078711.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Holocene surface rupture history of an active forearc fault redefines seismic hazard in Southwestern British Columbia, Canada |
| Series title | Geophysical Research Letters |
| DOI | 10.1029/2018GL078711 |
| Volume | 45 |
| Issue | 21 |
| Publication Date | November 05, 2018 |
| Year Published | 2019 |
| Language | English |
| Publisher | American Geophysical Union |
| Contributing office(s) | Geology, Minerals, Energy, and Geophysics Science Center |
| Description | 7 p. |
| First page | 11605 |
| Last page | 11611 |
| Country | Canada |
| State | British Columbia |
| Other Geospatial | Leech River Fault, Vancouver Island |