ABSTRACT

On 8 January 2017 (23:47:11 UTC), a moment magnitude (Mw) 5.9 earthquake occurred in the Barrow Strait, 93 km southeast of Resolute, Nunavut, in the Canadian Arctic. This earthquake was one of the largest to occur in eastern Canada in the past 50 yrs. It was followed by 33 locatable aftershocks, two of which had an Mw greater than 5.0. Regional centroid moment tensor (RCMT) inversions for the mainshock and largest aftershocks are predominantly indicative of thrust faulting in response to northeast–southwest compression. These solutions are consistent with the broader regional stress field and with the orientation of mapped rift faults on nearby Somerset Island, although we cannot associate the Barrow Strait earthquakes with any specific fault. Moment tensor inversions and analyses of teleseismic depth phases all indicate that the mainshock was a deep crustal event that occurred at a depth of approximately 33–35 km. The aftershocks also appear to be deep, but their depths are not well constrained. The Barrow Strait mainshock was reported to have been felt in several communities, a rarity in the Arctic; this allowed us an opportunity to assess attenuation as a function of distance. In comparison to the 1988 Saguenay earthquake that occurred in southeastern Canada, which was of a similar size and depth, the felt reports are consistently of lower intensity, suggesting higher attenuation in the Arctic. A comparison of ground‐motion prediction equations (GMPEs) to recorded signals also suggests higher attenuation of velocity in the Arctic. While the Barrow Strait aftershock sequence was ongoing, an Mw 4.7 earthquake occurred approximately 500 km northwest of Resolute. Analysis of seismicity rates shows that these events occurred during a time period of enhanced seismic activity in the Arctic. Similar periods of high activity have been observed over the past few decades, but they appear to be short‐lived and not indicative of a long‐term increase in seismic activity.

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