Global displacements caused by point dislocations in a realistic Earth model
Global displacements caused by point dislocations in a realistic Earth model
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DOI：
10.1029/95jb03536
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发表时间：
1996-04
影响因子：
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通讯作者：
Wenke Sun;S. Okubo;P. Vaníček
中科院分区：
文献类型：
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作者：
Wenke Sun;S. Okubo;P. Vaníček
定义位错Love数[h nm ij，l nm ij，k nm ij，l nm t，ij ]和绿色函数来描述点位错引起的地球弹性变形，并研究了径向非均匀球形地球模型中的同震位移。我们推导出球谐表达式的剪切和拉伸位错，这可以表示为四个独立的解决方案：垂直走向滑动，垂直倾向滑动，拉伸开口在水平面上，和拉伸开口在垂直平面上。我们进行了计算与径向非均匀地球模型（1066A）。结果表明，地震近场形变占主导地位，随着震中距的增大，近场形变迅速衰减。点源越浅，位移越大。地球曲率和垂直分层对形变场都有相当大的影响。特别是垂直分层在震中距0.1°处可造成10%的差异。作为一个例子，我们计算了1964年阿拉斯加地震（MW = 9.2）引起的理论位移，并将结果与10个台站的观测垂直位移进行了比较。近场分析结果表明，竖向位移可达数米。远场位移也是显著的。例如，水平位移（μ m）在震中距离为30°时可以大到1 cm，在大约40°时可以大到0.5 cm，这些幅度可由现代仪器检测，例如卫星激光测距（SLR）、甚长基线干涉测量（VLBI）或全球定位系统（GPS）。全球范围内，地震引起的位移（u r）大于0.25 mm。
We define dislocation Love numbers [h nm ij , l nm ij , k nm ij , l nm t , ij ] and Green's functions to describe the elastic deformation of the Earth caused by a point dislocation and study the coseismic displacements caused in a radially heterogeneous spherical Earth model. We derive spherical harmonic expressions for the shear and tensile dislocations, which can be expressed by four independent solutions : a vertical strike slip, a vertical dip slip, a tensile opening in a horizontal plane, and a tensile opening in a vertical plane. We carry out calculations with a radially heterogeneous Earth model (1066A). The results indicate that the dominating deformations appear in the near field and attenuate rapidly as the epicentral distance increases. The shallower the point source, the larger the displacements. Both the Earth's curvature and vertical layering have considerable effects on the deformation fields. Especially the vertical layering can cause a 10% difference at the epicentral distance of 0.1°. As an illustration, we calculate the theoretical displacements caused by the 1964 Alaska earthquake (m w = 9.2) and compare the results with the observed vertical displacements at 10 stations. The results of the near field show that the vertical displacement can reach some meters. The far-field displacements are also significant. For example, the horizontal displacements (u ψ ) can be as large as 1 cm at the epicentral distance of 30°, 0.5 cm at about 40°, magnitudes detectable by modern instrument, such as satellite laser ranging (SLR), very long baseline interferometry (VLBI) or Global Positioning System (GPS). Globally, the displacement (u r ) caused by the earthquake is larger than 0.25 mm.