Waveform Similarity of Micro-Seismicity at the ToC2ME Hydraulic Fracturing Experiment Site

Abstract

ABSTRACT: This study quantitatively investigates the waveform similarity of micro-earthquakes detected during the Tony Creek Dual Microseismic Experiment (ToC2ME) conducted near Fox Creek, Alberta. Subsurface anthropogenic activities, especially processes involving injection, can lead to accumulation of pore pressure and elastic strain among the geologic formations and rocks, resulting in induced earthquakes. Four hydraulic-fracturing treatment wells were stimulated in the middle of the study area. An acquisition system monitored continuous seismic waveforms from 25 October to 15 December 2016 revealing 4083 hydraulic fracture-related events with magnitude ranging from Mw from -1 to 3.2. The present study compares and discusses similarity of waveforms captured by these stations using the PageRank method to form families of similar waveforms and rank their relative importance within their family. Waveforms corresponding to earthquake events are extracted from 3 representative stations for analysis. Preliminary results reveal earthquake families spatially gathered around the injection wells. Of the three main clusters located in the center, west, and east of the well, the central cluster showed the widest range of PageRank values, and also contained the highest PageRank value events. Events that happened before injection programme are more likely to have high PageRank values. There is also a slight positive correlation between PageRank value and magnitude. Overall, early events have more direct or indirect links than subsequent events. 1. INTRODUCTION Documented earthquakes events in North America have shown a dramatic increase in the past two decades, especially in northwestern and southern United States and western Canada. Previous research notes the emergence of small-scale earthquakes that are closely related to human activities, especially hydraulic fracturing and saltwater disposal (Atkinson et al., 2014, Konstantinovskaya et al., 2021, Schultz et al., 2020). This can partially be attributed to the implementation of improved monitoring technologies with higher capability for capturing earthquake events below a local magnitude (ML) of 2.5, denoted as micro-earthquakes.