Tidal and Thermal Stresses Drive Seismicity Along a Major Ross Ice Shelf Rift
Tidal and Thermal Stresses Drive Seismicity Along a Major Ross Ice Shelf Rift
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DOI：
10.1029/2019gl082842
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发表时间：
2019-06
影响因子：
5.2
通讯作者：
S. Olinger;B. Lipovsky;D. Wiens;R. Aster;P. Bromirski;Z. Chen;P. Gerstoft;A. Nyblade;R. Stephen
中科院分区：
文献类型：
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作者：
S. Olinger;B. Lipovsky;D. Wiens;R. Aster;P. Bromirski;Z. Chen;P. Gerstoft;A. Nyblade;R. Stephen
了解冰架的变形对于评估冰架对减薄的响应是必要的。我们研究微震与冰架变形使用九个宽带地震仪部署在罗斯冰架上的裂缝附近。从2014年12月到2016年11月，我们检测到5，948次由裂谷变形产生的冰震。使用最小二乘网格搜索和双差算法确定了2，515起事件的位置。海洋膨胀、亚重力波和重大海啸的到来不会影响地震活动。相反，地震活动性与潮汐相的昼夜时间尺度和气温的多日和季节的时间尺度呈负相关。潮汐高度的空间变化使冰架倾斜，地震活动集中在冰架朝冰锋向下倾斜时。在特别寒冷的时期，热应力和脆化作用使裂缝沿着扩展。我们认为，热应力和潮汐驱动的重力应力产生裂谷地震活动与高峰活动在冬季。
Understanding deformation in ice shelves is necessary to evaluate the response of ice shelves to thinning. We study microseismicity associated with ice shelf deformation using nine broadband seismographs deployed near a rift on the Ross Ice Shelf. From December 2014 to November 2016, we detect 5,948 icequakes generated by rift deformation. Locations were determined for 2,515 events using a least squares grid‐search and double‐difference algorithms. Ocean swell, infragravity waves, and a significant tsunami arrival do not affect seismicity. Instead, seismicity correlates with tidal phase on diurnal time scales and inversely correlates with air temperature on multiday and seasonal time scales. Spatial variability in tidal elevation tilts the ice shelf, and seismicity is concentrated while the shelf slopes downward toward the ice front. During especially cold periods, thermal stress and embrittlement enhance fracture along the rift. We propose that thermal stress and tidally driven gravitational stress produce rift seismicity with peak activity in the winter.