Grounding zone subglacial properties from calibrated active-source seismic methods
Grounding zone subglacial properties from calibrated active-source seismic methods
复制标题
来自校准主动源地震方法的接地区冰下特性
DOI：
10.5194/tc-2020-147
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
M. Siegfried
中科院分区：
文献类型：
--
作者：
H. Horgan;Laurine van Haastrecht;R. Alley;S. Anandakrishnan;L. Beem;K. Christianson;A. Muto;M. Siegfried
抽象。西南极洲Whillans冰流的接地带在0.5-1 km的距离内表现出从接地冰到海洋空腔的基础性质的突变。主动源地震方法揭示了冰流的冰下最接地部分的基础是相对坚硬的基底（相对较高的剪切波速度为1100±430 m s-1），而冰流下方其他地方发现的是可变形的冰碛物。在我们的研究领域的基础反射率的变化不能解释的阶段的潮汐。在接地区上游几公里处，检测到冰下水层，以及似乎是水层但小于我们技术可分辨厚度的区域。坚硬的冰下沉积物和薄水层的接地区上游的存在支持以前的研究，提出了接地区内的沉积物脱水和捕获的冰下水的海洋腔上游。该设置使我们的方法使用浮动冰架返回校准。这使得不同的技术用于估计的地震源的大小，一个约束条件的精确恢复冰下的属性是必不可少的比较。我们发现我们的校准方法和常用的多次反弹方法之间存在很强的相关性（决定系数=0.46），但我们的结果也强调了对影响冰冻圈中震源和反射振幅的其他因素的不完整了解。
Abstract. The grounding zone of Whillans Ice Stream, West Antarctica, exhibits an abrupt transition in basal properties from the grounded ice to the ocean cavity over distances of less than 0.5–1 km. Active-source seismic methods reveal the downglacier-most grounded portion of the ice stream is underlain by a relatively stiff substrate (relatively high shear wave velocities of 1100±430 m s−1) compared to the deformable till found elsewhere beneath the ice stream. Changes in basal reflectivity in our study area cannot be explained by the stage of the tide. Several kilometres upstream of the grounding zone, layers of subglacial water are detected, as are regions that appear to be water layers but are less than the thickness resolvable by our technique. The presence of stiff subglacial sediment and thin water layers upstream of the grounding zone supports previous studies that have proposed the dewatering of sediment within the grounding zone and the trapping of subglacial water upstream of the ocean cavity. The setting enables calibration of our methodology using returns from the floating ice shelf. This allows a comparison of different techniques used to estimate the sizes of the seismic sources, a constraint essential for the accurate recovery of subglacial properties. We find a strong correlation (coefficient of determination=0.46) between our calibrated method and a commonly used multiple-bounce method, but our results also highlight the incomplete knowledge of other factors affecting the amplitude of seismic sources and reflections in the cryosphere.
影响因子：
5.3
作者：
Smith, Andrew M.;Woodward, John;King, Edward C.
通讯作者：
King, Edward C.
使用南极洲西部思韦茨冰川的地震数据关联河床特征和冰下形态
影响因子：
5.3
作者：
Muto, Atsuhiro;Anandakrishnan, Sridhar;Alley, Richard B.;Horgan, Huw J.;Parizek, Byron R.;Koellner, Stephen;Christianson, Knut;Holschuh, Nicholas
通讯作者：
Holschuh, Nicholas
影响因子：
5.2
作者：
Bindschadler, R.;Choi, H.;Young, N.
通讯作者：
Young, N.