Co-seismic deformation and gravity field changes caused by the 2011 Mw6.8 Myanmar and Mw6.9 India-Nepal earthquakes are calculated with a finite-element model and an average-slip model,respectively,based on the multi-layered elastic half-space dislocation theory.The calculated maximum horizontal displacement of the Myanmar earthquake is 36 cm,which is larger than the value of 9.5 cm for the India-Nepal earthquake.This difference is attributed to their different focal depths and our use of different models.Except certain differences in the near field,both models give similar deformation and gravity results for the Myanmar event.
Based on co-seismic displacements recorded by terrestrial GPS stations and seafloor GPS/acoustic stations, the static slip model of the 2011 Mw 9.0 Tohoku earthquake was determined by inverting the data using a layered earth model. According to a priori information, the rupture surface was modeled with a geometry that is close to the actual rupture, in which the fault dip angle increases with depth and the fault strike varies with the trend of the trench. As shown by the results inferred from the joint inversion, the "geodetic" moment is 3.68 × 10 22 Nm, corresponding to Mw 9.01, and the maximum slip is positioned at a depth of 13.5 km with a slip magnitude of 45.8 m. Rupture asperities with slip exceeding 10 m are mainly distributed from 39.6 to 36.97°N, over a length of almost 240 km along the trench. The slip was mostly concentrated at depths shallower than 40 km, up-dip of the hypocenter. "Checkerboard" tests reveal that a joint inversion of multiple datasets can resolve the slip distribution better than an inversion with terrestrial GPS data only-especially when aiming to resolve slip at shallow depths. Thus, the joint inversion results obtained by this work may provide a more reliable slip model than the results of other studies that are only derived from terrestrial GPS data or seismic waveform data.
Based on the elastic dislocation theory, multilayered crustal model, and rupture model obtained by seismic waveform inversion, we calculated the coand post-seismic surface deformation and gravity changes caused by the Yushu M W 6.9 earthquake occurred on April 14, 2010. The observed GPS velocity field and gravity field in Yushu areas are disturbed by the coand post-seismic effects induced by Yushu earthquake, thus the theoretical coand post-seismic deformation and gravity changes will provide important modification for the background tectonic movement of Yushu and surrounding regions. The time relaxation results show that the influences of Yushu earthquake on Yushu and surrounding areas will last as long as 30 to 50 years. The maximum horizontal displacement, vertical uplift and settlement are about 1.96, 0.27 and 0.16 m, respectively, the maximal positive and negative value of gravity changes are 8.892×10-7 m·s-2 and -4.861×10-7 m·s-2 , respectively. Significant spatial variations can be found on the coand post-seismic effects: The co-seismic effect mainly concentrates in the region near the rupture fault, while viscoelastic relaxation mostly acts on the far field. Therefore, when using the geodetic data to research tectonic motion, we should not only consider the effect of co-seismic caused by earthquake, but also pay attention to the effect of viscoelastic relaxation.
用为 8 h 的测量 GPS 的 coseismic 和 seismic 以后排水量跟随 M w 2011 年 3 月 11 日， coseismic 和 seismic 以后差错的 9.0 仙台地震滑动模型基于一个分层的外壳的模型被开发。主要吃惊的测地学的时刻大小是被测量近似 M w 8.98。slip 展出清楚的反向的特征，与大约 23.3 m 的 hypocenter，和大小附近的最大值。某罢工滑倒行为可以发生在山峰破裂地区的二个方面上。主要吃惊释放的几乎 90% 地震时刻发生在深度不到 40 km。精力由差错释放了在跟随主要吃惊的 8 h 滑倒近似等于 M w 的地震 8.13。与 1.5 m 的最大值， seismic 以后滑倒在 coseismic 破裂差错的西南的部分被集中，它与 M w 的地点和行为同意很好 7.9 余震。这暗示在在主要吃惊以后的 8 h 的 seismic 以后变丑被 M w 主要导致 7.9 余震。另外， seismic 以后 0.20.4 m 滑倒在 coseismic 破裂的下面剧降延期被观察，它可能被在滑倒以后的效果在这个时期期间引起了。
A linear projection approach is developed to present geoscience research result in planar coordinate system projected from spherical coordinate system. Here, the sphere is intersected by a plane and its surface is projected onto the plane. In order to keep the projected coordinate system orthogonal, and minimize the distortion, one axis of the planar coordinate system is chosen in our projection based on the shape of the region to be projected, and the other axes can be chosen arbitrarily or based on the constraint of the orthogonality. In the new method the projection is self-contained. The forward projection can be fully projected backward without loss of precision. The central area of the sphere will be projected to the planar system without distortion, and the latitudinal length in the rotated spherical system keeps constant during the projecting process. Only the longitudinal length in the rotated spherical system changes with the rotated latitude. The distortion of the projection therefore, overall, is small and suitable for geoscience studies.
