Summary
We perform an in depth analysis of the Crooked Lake earthquake sequence occurring between November 29, 2013 and December 13, 2013 near Fox Creek, Alberta. A total of 24 events were detected during this time using a traditional STA/LTA triggering mechanism. We use the largest event, a magnitude 3.9, as a template event and perform waveform cross correlation to try and identify events not detected by the STA/LTA trigger. Over the fifteen day period the cross correlation detection method identified 113 locatable events including all of the 24 events detected by the STA/LTA trigger. We calculate the magnitude of completeness using a maximum curvature method (Wiemer and Wyss, 2000) and compare the result for the STA/LTA catalogue and the cross correlation catalogue. We observe a reduction of approximately 0.8 magnitude units in magnitude of completeness. Our results support previous findings (e.g. Gibbons and Ringdal, 2006) that cross correlation detection methods can offer significantly lower detection thresholds when compared to traditional triggering mechanisms. The improved detection ability results in a more complete catalogue that may provide an opportunity to gain information about the precursors to induced seismicity or facilitate efforts to image the structure of the area.
