On 30 November 2018, a felt (ML 4.5) seismic event occurred ~16 km from Fort St. John, British Columbia, that has been attributed to ongoing hydraulic fracturing operations in the area. The mainshock was followed by two felt aftershocks (>ML 3.4) in the following hour. All of the events were tightly clustered, both spatially and in depth, and appear to be related to a southern boundary fault of the Fort St. John Graben complex. Stress inversion of a number of focal mechanisms suggests that the maximum principal stress is well constrained and almost horizontal, however the intermediate- and minimum-principal stresses are poorly constrained between the vertical and minimum horizontal stress. This results in a variety of focal mechanisms from the detected seismicity, and indicates a high complexity in the local stress regime. Hypocenters appear to locate at the confluence between a large-scale reverse faulting style regime (to the north-west, probably due to the influence of the Rocky Mountain fold and thrust belt) and an oblique strike slip faulting regime (to the south-east, probably due to influence of the Fort St. John Graben complex).
Presentation Date: Monday, October 12, 2020
Session Start Time: 1:50 PM
Presentation Time: 1:50 PM
Presentation Type: Oral