中文摘要：

利用＂中国地壳运动观测网络（二期）＂245个GPS连续观测站及其他站的大量观测结果,采用离震中很远的7个GPS站作为位错参考框架,得到2011年3月11日东日本Mw9.0大地震的同震水平位移和应变。此种参考框架的位移场解,符合弹性位错模型离震中很远且水平位移接近于0的要求,不仅有利于位错模型反演,也有利于合理分析此次大地震同震水平位移的影响范围。地震前后区域参考框架下远场GPS连续观测位移时间序列和同震位移弹性位错模型反演结果表明,东日本大地震同震水平位移既是地震断层破裂的结果,也是远场震前数月或数年水平位移的弹性回跳,据此可以进一步确认这些站震前水平位移前兆异常。由于这些震前异常位移中亦包含了同震位移量（方向相反）,因此,弹性位错模型为定量研究大地震前远场地壳运动异常提供了一种理论模型。位错参考框架中的同震位移及其位错模型和区域参考框架的位移时间系列的综合研究有助于对此次大地震地壳运动异常的认识。这种持续时间为数月至数年的弹性形变异常,可以为大地震的中短期预测提供依据。

英文摘要：

In this paper the coseismic horizontal displacements and strains of the Mw9.0Tohoku earthquake on March 11,2011 in Japan are obtained from continuous GPS observations at 245 stations in the Crustal Movement Observation Network of China（CMONOC）and other stations based on the dislocation reference frame with 7core stations that are much more far away from the earthquake epicenter according to the elastic dislocation theory.The far field horizontal displacements at stations further away from the epicenter are close to zero and in good agreement with the theoretical elastic dislocation model.More reasonable elastic dislocation models can be inverted from the coseismic horizontal displacements observed by GPS in this reference frame.In addition,the influence area of this earthquake can be reasonably estimated from these displacements.Time series of far field displacements in the regional reference frame at continuous GPS observation stations show that the coseismic horizontal displacements are not only the result of the rupture of the earthquake fault but also the elastic rebound of the displacements accumulated during several months or even several years before the earthquake.Therefore the preseismic displacements at these stations wereprecursory anomalous before the Tohoku earthquake in Japan and they contained at least the coseismic displacements at these stations in opposite sense.So the elastic dislocation model is one of the theoretical models that can also be used in qualitative studies on anomalous displacements before similar great earthquakes.Therefore,it is even more important that comprehensive studies on the coseismic horizontal displacements in the dislocation reference frame,their elastic dislocation model and the time series of horizontal displacements in the regional reference frame are instrumental to explaining and understanding of anomalous crustal movements before this giant event.The anomalous elastic displacements with a duration of several months or several years could be used in mid or sho