09:15 〜 09:30
[S01-3-04] The January 2017 Barrow Strait Earthquake and Subsequent Seismic Activity in Arctic Canada
At 23:47 UT on 8 January 2017, a magnitude (MW) 5.9 earthquake, one of the largest in eastern Canada during the last 50 years, occurred just offshore of Somerset Island, in Barrow Strait 92 km from Resolute in northern Canada. The earthquake occurred near the Boothia Uplift of the Boothia-Ungava Seismic Zone and was well recorded by the newly refurbished seismograph in Resolute (RESN). An earthquake of this size is expected about once every 300 years based on the statistics for the Somerset-Cornwallis Island seismic source zone; the rate for Barrow Strait by itself is higher than for the larger region. The mainshock was followed by a rich and ongoing aftershock sequence. As of 6 February 2017 there were eight aftershocks of magnitude 3.0 or greater and numerous smaller ones with the largest being a magnitude 5.1 event that occurred at 17:55 UT on 9 January. Moment tensor inversion of the mainshock and largest aftershock indicates that they were predominantly thrust faulting events on a northwest-striking plane consistent with past events in Barrow Strait including the 1987 magnitude 5.2 event that occurred 30 km NW of the January 8 mainshock. We will discuss the characteristics of the mainshock, seismotectonics of the region, an analysis of the aftershock sequence, depth estimation using a variety of methods such as moment tensor inversion and analysis of teleseismic depth phases. On 20 January 2017 another moderately large (MW 4.7) earthquake occurred in the Arctic Islands about 97 km from Isachsen, Nunavut. This event has an oblique-thrust mechanism. There are few recorded aftershocks for this event but we note that the closest station is at a distance of 475 km. While too far (575 km) to be considered an aftershock of the Barrow Strait earthquake, the occurrence of the two events over a short time period raises the question of a causal relation.