[1] In north China, most earthquakes occur at depths of 10-25 km and are considered to be the direct result of deformation or rupture of the brittle upper crustal layer. To describe this mechanism, a planar horizontal negative dislocation plane is used to represent the force of action of the lower crustal layer on an overlying brittle upper crust layer. An area around Beijing in north China has been chosen for applying this negative dislocation layer assumption. A GPS network (Capital Circle GPS Network, CCGN), has been set up for monitoring crust deformations since 1992. In this paper, observations from 1992, 1995, and 1996 GPS surveying campaigns were used to determine model parameters of a negative dislocation layer. Using a Bayesian inversion procedure, more than 95% of data residuals are found to be<2mm/yr, indicating that the negative dislocation layer model can fit GPS data well. The inversion results show that the local tectonic movement is 2

详细推导了由地心坐标系中到测站坐标系中的速度转换公式及误差传播公式，并且计算了931个GPS测站点在球面测站坐标系与椭球面测站坐标系中速度分量之间的差别。结果表明，测站高度对速度归算影响的相对变化量在10-4～10-3量级（对于厘米级的速度分量而言,可以忽略不计），球面站心坐标系和椭球面站心坐标系下的速度分量差别主要表现在测站速度的北分量上，通常为10-6～10-5量级，可以忽略不计。但是，对于垂直速度分量较大的测站，两者的差别比较明显。

Monitoring of the crustal movements along a tectonic fault is of particular importance in the study of the mechanism of an earthquake. There are several techniques to gauge crustal deformations, including terrestrial survey methods, space-positioning techniques and permanently installed geotechnical instruments. Each technique or method has its own advantages and limitations. Integration of the various techniques into a monitoring scheme is recommended. It is discussed how a proper integrated system can significantly improve the separability of a monitoring scheme at little additional expense. Separability is the ability of a monitoring scheme to distinguish among potential deformation models, and can be used for the optimum design of monitoring schemes. Discussion concentrates on the separability between a dislocation model and a rigid movement model in the area of an active fault. The addition of a few strain observations to a conventional terrestrial survey scheme can better distinguish between the above-mentioned models. A simulated example is presented to demonstrate the idea.

In this paper, the velocities of 154 stations obtained in 2001 and 2003 GPS survey campaigns are applied to formulate a continuous velocity field by the least-squares collocation method. The strain rate field obtained by the least-sqares collocation method shows more clear deformation patterns than that of the conventional discrete triangle method. The significant deformation zones obtained re mainly located in three places, to the north of Tangshan, between Tianjing and Shijiazhuang, and to the north of Datong, which agree with the places of the Holocene active deformation zones obtained by geological investigations. The maximum shear strain rate is located at latitude 38.6◦N and longitude 116.8◦E, with a magnitude of 0.13ppm/a. The strain rate field obtained can be used for earthquake prediction research in the North China Basin.