TILL BENEATH ICE STREAM-B .1. PROPERTIES DERIVED FROM SEISMIC TRAVEL-TIMES
TILL BENEATH ICE STREAM-B .1. PROPERTIES DERIVED FROM SEISMIC TRAVEL-TIMES
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DOI：
10.1029/jb092ib09p08903
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发表时间：
1987-08-10
期刊：
影响因子：
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通讯作者：
ALLEY, RB
中科院分区：
文献类型：
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作者：
BLANKENSHIP, DD;BENTLEY, CR;ALLEY, RB
在南极洲西部海洋冰盖的一部分冰流B上进行的地震实验显示，在1000米厚的冰层下面有一层米厚的冰层。进行了一项地震实验，包括沿沿着平行于冰流的线进行广角反射剖面测量，以确定该层的特性。地震走时反演得到该层的纵波速度小于1700 m s-1，横波速度小于160 m s-1。这些非常低的波速意味着该层中的材料是高度多孔的，并且在高孔隙压力下被水饱和。根据其他饱和、松散沉积物中的波速，我们认为孔隙度大大大于0.32，可能在0.4左右，上覆压力超过孔隙压力仅50 kPa（0.5 bar），这是该位置地层的特征。
Seismic experiments conducted on ice stream B, part of the marine ice sheet of West Antarctica, show a meters‐thick layer immediately beneath the 1000‐m‐thick ice. A seismic experiment consisting of wide‐angle reflection profiling along a line parallel to ice stream flow was conducted to determine the properties of this layer. Inversion of seismic travel times yields a compressional wave speed of less than 1700 m s−1and a shear wave speed less than 160 m s−1for the layer. These very low wave speeds imply that the material in the layer is highly porous and is saturated with water at a high pore pressure. Based on wave speeds in other saturated, unconsolidated sediments, we believe that a porosity substantially greater than 0.32, probably around 0.4, and an excess of overburden pressure over pore pressure of only 50 kPa (0.5 bar) characterize the layer at this location.