We present a series of simple shear numerical simulations of dynamic recrystallization of two‐phase nonlinear viscous materials that represent temperate ice. First, we investigate the effect of the presence of water on the resulting microstructures and, second, how water influences on P wave (V_p) and fast S wave (V_s) velocities. Regardless the water percentage, all simulations evolve from a random fabric to a vertical single maximum. For a purely solid aggregate, the highest V_p quickly aligns with the maximum c‐axis orientation. At the same time, the maximum c‐axis development reduces V_s in this orientation. When water is present, the developed maximum c‐axis orientation is less intense, which results in lower V_p and V_s. At high percentage of water, V_p does not align with the maximum c‐axis orientation. If the bulk modulus of ice is assumed for the water phase (i.e., implying that water is at high pressure), we find a remarkable decrease of V_s while V_p remains close to the value for purely solid ice. These results suggest that the decrease in V_s observed at the base of the ice sheets could be explained by the presence of water at elevated pressure, which would reside in isolated pockets at grain triple junctions. Under these conditions water would not favor sliding between ice grains. However, if we consider that deformation dominates over recrystallization, water pockets get continuously stretched, allowing water films to be located at grain boundaries. This configuration would modify and even overprint the maximum c‐axis‐dependent orientation and the magnitude of seismic anisotropy.

中文翻译：

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极地冰盖中温带冰的地震各向异性

我们提出了代表温带冰的两相非线性粘性材料动态再结晶的一系列简单剪切数值模拟。首先，我们研究了水的存在对最终微结构的影响，其次，水对P波（V _p）和快速S波（V _s）速度的影响。无论水含量如何，所有模拟都从随机的织物演变为垂直的单个最大值。对于纯固态的骨料，最高的V _p快速与最大的c轴方向对齐。同时，最大的c轴展开减小了V _s在这个方向上。当存在水时，展开的最大c轴方向的强度降低，从而导致V _p和V _s降低。在高百分比水的情况下，V _p与最大c轴方向不对齐。如果假定水相的冰的体积模量（即，暗示水处于高压状态），我们发现V _s显着下降，而V _p保持接近纯固体冰的值。这些结果表明，V _s的降低在冰盖底部观察到的现象可以用存在于高压下的水来解释，该水将驻留在谷物三重连接处的隔离袋中。在这些条件下，水将不利于冰粒之间的滑动。但是，如果我们认为变形在重结晶过程中占主导地位，那么水囊会不断拉伸，从而使水膜位于晶界处。这种配置将修改甚至覆盖最大的c轴相关方向和地震各向异性的大小。