Source Parameters of the Nov 30, 2018, ML 4.5 Hydraulic Fracturing Induced Earthquake and Aftershock Sequence in Northeast BC, Canada

Date: 4/26/2019

Time: 04:00 PM

Room: Cascade I

Seismicity related to fluid injection in the exploration of unconventional oil and gas resources has increased dramatically in the Western Canada Sedimentary Basin in the last decade. Hydraulic fracturing is considered to be the main cause of several M4+ events in the Montney Play, including the ML 4.5 mainshock on November 30, 2018 (November 29, local time), in the Dawson-Septimus area. It is the second largest hydraulic fracturing induced event in northeast BC. In order to understand the underlying source physics, we conduct a comprehensive source parameter study of the mainshock and its aftershock sequence, using waveform data from 15 broadband seismic stations (9 McGill, 6 Natural Resources Canada) deployed at distances ranging from ~1 to 50 km from the mainshock epicenter. We first enhance the seismicity catalog for the period of 2018/11/20 to 2018/12/10 from 16 (NRCan reported) to 212 events using a multi-station matched-filter (MMF) method. Preliminary locations of the MMF detected events highlight a NW-SE trending structure, which is, in general, consistent with the fault plane solutions of both the 2018/11/30 ML 4.5 and 2015/08/17 ML 4.6 hydraulic fracturing induced events. The latter event was ~ 100 km north of Fort St John, suggesting the influence of the regional principal stress. The spectral ratio analyses suggest a stress drop value of ~0.1 MPa for the mainshock, compared to values of ~ 10 MPa for the two largest aftershocks, possibly reflecting different rupture mechanisms of the mainshock from the aftershocks. Results from high-precision hypocenter relocation using the MMF catalog will be presented to better illustrate the spatiotemporal migration of seismicity. Once the industrial injection data becomes available, we will model the solid matrix stress and fluid pressure changes due to injection using a coupled poroelasticity model and correlate the modeling results with seismicity.

Presenting Author: John Onwuemeka

Authors