Examining micro-seismicity across southern Vancouver Island: applying automated detection to augment existing seismic catalogues

Southern Vancouver Island sits atop the northern end of the Cascadia Subduction zone, and therefore is prone to a high level of seismic hazard from the megathrust. However, the region is also home to numerous crustal faults, many of which are poorly constrained as to their activity in the Holocene. Past catalogues derived from widely spaced instrumentation were not always capable of accurately detecting and locating micro-seismicity across this region. Of particular interest is the Leech River Fault (LRF) and Leech River Valley Fault (LRVF) which cross from the west coast of Southern Vancouver Island, through Victoria, and meet with the Devils Mountain Fault (DMF) in the Strait of Juan de Fuca. Both the DMF and LRVF have evidence for Holocene activity. With this project, we focus on applying the S-SNAP detection and location code to augment the Natural Resources Canada Earthquake Catalogue through this region, using additional local instruments (from the nearby LRF Experiment and regional Raspberry Shakes). We present preliminary findings on several key months of seismicity, evaluating the capability of the S-SNAP methodology to this setting, and present preliminary findings on the distribution of small-scale seismicity across the greater Capital Region District and southern Vancouver Island.