Spatiotemporal Variations in Crustal Seismic Anisotropy Surrounding Induced Earthquakes Near Fox Creek, Alberta
Spatiotemporal Variations in Crustal Seismic Anisotropy Surrounding Induced Earthquakes Near Fox Creek, Alberta
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DOI：
10.1029/2018gl081766
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发表时间：
2019-05
影响因子：
5.2
通讯作者：
Tianyang Li;Y. Gu;Zizhen Wang;Ruijia Wang;Yunfeng Chen;T. Song;Ruihe Wang
中科院分区：
文献类型：
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作者：
Tianyang Li;Y. Gu;Zizhen Wang;Ruijia Wang;Yunfeng Chen;T. Song;Ruihe Wang
本研究分析了阿尔伯塔福克斯溪附近四个近源（<10 km）台站的地震记录，该地区以水力压裂引起的地震活动而闻名。我们研究了沉积地层中震源机制和地震各向异性的时空变化。周围震群的震源机制与ML 4.6地震的走滑机制基本一致，有利于花型断层结构。根据剪切波分裂测量结果确定的NE-SW向快速分裂方向反映了（1）N-S断层和（2）NE-SW时变水力压裂裂缝的综合影响。后一种效应在主震前的几天内主导了视各向异性，而主震后其贡献减少了60-70%。流体损失到断层损害区，这导致裂缝闭合，是负责观察到的时空变化的地震各向异性水力压裂井附近。
This study analyzes earthquake recordings from four near‐source (<10 km) stations near Fox Creek, Alberta, a region known for hydraulic fracturing‐induced seismicity. We examine the spatiotemporal variations of focal mechanisms and seismic anisotropy in the sedimentary strata. The focal mechanisms of surrounding earthquake swarms are generally consistent with the strike‐slip mechanism of the ML 4.6 earthquake, favoring a flower type of fault structure. The NE‐SW‐orientated fast splitting direction, determined from the shear wave splitting measurements, reflects the combined effects of (1) N‐S faults and (2) NE‐SW time‐dependent hydraulically stimulated fractures. The latter effect dominates the apparent anisotropy during the days leading to the mainshock, while its contributions are reduced by 60–70% after the mainshock. Loss of fluid into the fault damage zone, which causes the closure of fractures, is responsible for the observed spatiotemporal variation of seismic anisotropy near the hydraulic fracturing well.