Treatment of discontinuities inside Earth models: Effects on computed coseismic deformations
Treatment of discontinuities inside Earth models: Effects on computed coseismic deformations
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地球模型内部不连续性的处理：对计算的同震变形的影响
DOI：
10.26464/epp2021010
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发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
Wenke Sun
中科院分区：
文献类型：
--
作者：
Jie Dong;Gabriele Cambiotti;Hanjiang Wen;Roberto Sabadini;Wenke Sun
在本文中，我们研究如何同震变形计算在1066地球模型的影响，如何处理地球的不连续性模型。从应用模型1066 A（连续）和1066 B（不连续）的结果中，我们发现走滑和水平拉应力源的Love数差异大于倾滑和垂直拉应力源。总的来说，不连续性对四个独立源的绿色函数有重大影响。对于2013年鄂霍次克地震（Mw 8.3）的近场同震变形，由不连续性引起的垂直位移、大地水准面和重力变化的理论计算之间的总体差异分别为10.52%、9.07%和6.19%，RMS误差分别为0.624 mm、0.029 mm和0.063 μGal。与GPS数据相比，远场位移的差异很小，我们可以忽略这种影响。对于2011年东北冲地震（Mw9.0）的浅源地震，使用ARIA滑动模型计算的近场位移差异为0.030 m（N-S）、0.093 m（E-W）和0.025 m（up-down），结果更接近GPS数据，而不是USGS模型。由不连续面引起的地球表面垂直位移和重力变化的差异大于10%。根据GRACE数据的要求，在截断到60度的空间固定点处，理论重力变化的差异为0.0016 μGal，差异为11%，1066 B的理论空间重力变化比1066 A更接近观测值。结果表明，介质中存在不连续性的地球模型对同震形变的计算结果有很大影响。
In this paper, we study how coseismic deformations calculated in 1066 Earth models are affected by how the models treat Earth discontinuities. From the results of applying models 1066A (continuous) and 1066B (discontinuous), we find that the difference in Love numbers of strike‐slip and horizontal tensile sources are bigger than dip‐slip and vertical tensile sources. Taken collectively, discontinuities have major effects on Green’s functions of four independent sources. For the near‐field coseismic deformations of the 2013 Okhotsk earthquake (Mw 8.3), the overall differences between theoretical calculations in vertical displacement, geoid, and gravity changes caused by discontinuities are 10.52 percent, 9.07 percent and 6.19 percent, with RMS errors of 0.624 mm, 0.029 mm, and 0.063 μGal, respectively. The difference in far‐field displacements is small, compared with GPS data, and we can neglect this effect. For the shallow earthquake, 2011 Tohoku‐Oki earthquake (Mw 9.0), the differences in near‐field displacements are 0.030 m (N‐S), 0.093 m (E‐W), and 0.025 m (up‐down) in our study area with the ARIA slip model, which gives results closer to GPS data than those from the USGS model. The difference in vertical displacements and gravity changes on the Earth’s surface caused by discontinuities are larger than 10 percent. The difference in the theoretical gravity changes at spatially fixed points truncated to degrees 60, as required by GRACE data, is 0.0016 μGal and the discrepancy is 11 percent, with the theoretical spatial gravity changes from 1066B closer to observations than from 1066A. The results show that an Earth model with discontinuities in the medium has a large effect on the calculated coseismic deformations.
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