新丰江水库5.3级(1964)地震区三角网平差和震源参数反演>.

本文系统地介绍了地震区三角网平差和利用平差结果反演断层参数的随机尝试————动态平差方法.通过新丰江水库5.3级地震区三角测量资料的处理, 进一步阐述如何应用这种方法, 并给出反演5.3级地震断层参数结果:断层走向北东62, 倾向南东, 倾角59, 断层长4.7公里, 上界面深0.45公里, 下界面深4.5公里, 倾向滑距73.4毫米, 走向滑距25.5毫米, 为正断右旋走滑断层, 地震矩 m0=2.01024达因厘米, 应力降=12巴, 释放的应变能下限 E=1.21019尔格.文中依据所得结果, 结合地震机制和构造资料讨论了新丰江水库地震的力源问题, 指出区域应力场是主要力源, 水压应力场是主要的诱发力源。 

TRIANGULATION NET ADJUSTMENT AND THE FOCAL PARAMETERS OF THE 1964 MAGNITUDE 5.3 EARTHQUAKE OF THE XINFENGJIANG RESERVOIR AREA BY INVERSION

In this paper, the triangulation net adjustment in the Xinfengjiang reservoir area and the method of random try-motion adjustment used to get the fault parameters by inversion of the results of adjustment are systematically described. In treating the triangulation data before and after the magnitude 5.3 earthquake of the Xinfengjiang reservoir area it has been further made clear the applicability of the method.Through inversion, the parameters of the earthquake fault are: strike N62E, dipping to the southeast at an angle of 59, the length of the fault, 4.7 km, depth of its upper boundary, 0.45 km, lower boundary, 4.5 km, dip slip dislocation, 73.4 mm, strike slip dislocation, 25.5 mm. It is a normal right-lateral fault, seismic moment m0=2.01024 dyne-cm, stress drop =12 bars, strain energy release E=1.21019 ergs.It is also discussed the force system causing the earthquakes of the Xinfengjiang reservoir area based on the results thus obtained and the data of focal mechanisms and of tectonic structures. The conclusion is that the regional stress field constitutes the main cause, while the water pressure provides the triggering effect of the earthquakes.