Numerical modeling of seismic waves for estimating the influence of the Greenland ice sheet on observed seismograms
Numerical modeling of seismic waves for estimating the influence of the Greenland ice sheet on observed seismograms
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DOI：
10.1016/j.polar.2014.12.001
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发表时间：
2015-03
期刊：
影响因子：
1.8
通讯作者：
G. Toyokuni;H. Takenaka;M. Kanao;S. Tsuboi;Y. Tono
中科院分区：
文献类型：
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作者：
G. Toyokuni;H. Takenaka;M. Kanao;S. Tsuboi;Y. Tono
我们为多国格陵兰冰盖监测网络（GLISN）的观测计算了格陵兰岛下面一个真实结构模型的区域合成地震记录，包括地表地形和冰盖厚度。格陵兰冰盖的厚度和非均匀性会导致GLISN在冰面上观测到的地震波形失真。开发了一种计算精度低、计算量小的区域地震波场数值计算方法。在这里，我们计算了格陵兰冰盖在不同深度和不同机制下震源的四种结构模型的弹性波传播高达2 Hz。我们对一个现实的冰盖模型进行了计算，近地表震源产生了一个非常有特征的波列，其群速度小于冰中的s波速度，被认为是一个冰盖引导波，由自由表面和冰床之间的临界后反射叠加而成。我们将这种波命名为“Le”，类似于地壳导向波。此外，对更深震源的计算结果表明，地壳-尾波的群速度范围为~ 3.1 ~ 2.6 km/s，与格陵兰冰盖上观测到的特征波形一致。
We calculate regional synthetic seismograms for a realistic structure model beneath Greenland, including surface topography and ice sheet thickness, for observations of the multinational GreenLand Ice Sheet monitoring Network (GLISN). The thick and heterogeneous Greenland ice sheet can cause distortion of the seismic waveforms observed at the GLISN stations on ice. We developed a numerical technique that calculates accurate regional seismic wavefields with low computational requirements. Here, we calculate the elastic wave propagation up to 2 Hz for four structural models of the Greenland ice sheet from a seismic source at various depths and with different mechanisms. Our computations for a realistic ice sheet model, the near-surface seismic source produced a very characteristic wave train with a group velocity smaller than theS-wavespeed in the ice, considered to be an ice-sheet guidedSwave, developed by the superposition of post-critical reflections between the free surface and the ice bed. We named this wave “Le”, analogous to theLgwave, a crustally guidedSwave. Furthermore, computation for a deeper seismic source resulted in reinforcement of the crustalSg-coda wave with a group velocity range of ∼3.1–2.6 km/s, which agrees with the characteristic waveform observed on the Greenland ice sheet.