Compressive shear faults within arctic sea ice: Fracture on scales large and small
Compressive shear faults within arctic sea ice: Fracture on scales large and small
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DOI：
10.1029/2003jc002108
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发表时间：
2004-07-22
影响因子：
3.6
通讯作者：
Schulson, EM
中科院分区：
文献类型：
--
作者：
Schulson, EM
[ 1]我们研究了北极海冰内的断裂特征，这些特征是由陆地卫星7号和雷达卫星图像、航空勘测以及在实验室中对双轴压缩下加载到脆性破坏的试样的观察所揭示的。无论尺度如何，从千米到毫米，这些特征看起来都很相似。它们主要由横贯视野的狭窄线性构造，加上翼状和梳状次生裂缝组成。线性构造偶尔会相交，通常表现出右行或左行的相对运动，就像地壳内的走滑断层一样。我们称之为脆性压剪断层。它们是通过变形诱导二次裂纹的雁列连接而形成的。从应用的翼裂纹和梳状裂纹力学，我们估计的最大压缩应力附近的断层的发病，并发现我们的估计比较有利的原位测量由早期的研究人员冰盖破坏应力。为了解释海冰覆盖层的脆性行为，我们采用了一个最近的模型，其中的关键思想是在应力集中的应力积累和应力松弛之间的竞争的韧性到脆性的转变。在确定海冰断裂特征的性质，我们提出的观点是，故障发生在许多尺度上，通过高度本地化，而不是均匀分布的变形，通过操作的尺度无关的机制。
[ 1] We examined fracture features within arctic sea ice as revealed by Landsat-7 and RADARSAT imagery, by an aerial survey, and through observations in the laboratory of specimens loaded to brittle failure under biaxial compression. Regardless of scale, which spans the range from kilometers to millimeters, the features look alike. They consist mainly of narrow lineaments that traverse the field of view, plus wing-like and comb-like secondary cracks. The lineaments occasionally intersect and generally exhibit either right-lateral or left-lateral relative movement, like strike-slip faults within Earth's crust. We term them brittle compressive shear faults. They form through the linking of en echelon arrays of deformation-induced secondary cracks. From an application of wing-crack and comb-crack mechanics, we estimated the maximum compressive stress near the onset of faulting and found that our estimates compare favorably with in situ measurements by earlier investigators of ice sheet failure stresses. To account for the brittle behavior of the sea ice cover, we applied a recent model of the ductile-to-brittle transition in which the key idea is the competition between stress buildup and stress relaxation at stress concentrators. In identifying the nature of sea ice fracture features, we advance the view that failure occurs on many scales through highly localized as opposed to uniformly distributed deformation, via the operation of scale-independent mechanisms.