关键词: 城市断裂, 试验研究, 磁异常解析方法, 北京地区

Abstract: Beijing area is chosen as the testing field to study the urban fault.Aeromagnetic data in the field are processed using analytical methods of magnetic anomaly such as analytical downward continuation,spectrum analysis,regularization filtering,directional derivative,wavelet analysis,fractal dimension,inversion of apparent magnetization and inversion of magnetic surface.The effect,function and adaptability of various interpreting methods of magnetic prospecting are evaluated on the basis of analysis and contrast of a lot of data in the urban fault study.Instructional opinions are proposed about magnetic prospecting techniques in the future urban fault exploration after the test results are summarized.For example,the upward continuation and the regularization filtering or multi-scale separation of wavelets are effective for revealing deep faults.The height of upward continuation and the wavelength of regularization filtering should not be too big,otherwise,it is possible to enhance regional structures and restrain the information of local faults.Downward continuation and vertical derivative are effective for revealing shallow faults.It is necessary to control the largest downward continuation depth to the top of field source,otherwise,the data can not be used because of vibratory results.Horizontal derivative or wavelet analysis of high frequency is effective for revealing faults in the pre-judged direction.Inversion of apparent magnetization is effective for revealing faults in the area where there is a distinct difference of rock magnetism between two sides of the fault.Inversion of base magnetic surface is effective for revealing the vertical basement fault with a big shift of base magnetic surfaces between the two blocks along the fault.In addition,the testing results also show that spectrum analysis has a good effect on computing the field source depth for local anomaly,but not for regional anomaly.We hope that the study results can play an active role in the future exploration of urban faults.

Key words: urban fault, test study, Beijing area, analytical method of magnetic anomaly