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摘要
Accurate location of earthquake activity is essentially necessary for study of the detailed structure of faults, however, the standard location methods, such as various versions of Geiger's methods, don't work well any longer. Progress in computing technology at present has enabled us to directly face to the non-linear problem of earthquake location, so a new non-linear technique, which may be called time-reversal imaging technique (TRIT), is proposed for determining earthquake-hypocentroids. At first, the technique principle is illustrated by means of displacement representation law. Then feasibility is tested for using groups of numerical tests. Accuracy and objectivity of observation arrival time picking are promoted because direct P-wave train is used to build enveloped signal which is further employed to measure the observation arrival times by means of cross-correlation technique. Error caused by linearization of a non-linear problem is eliminated because a non-linear relation between earthquake location and observation arrival times is constructed based on beam-forming technique, which avoids the process of linearization in Geiger's methods. The disadvantage that least-squared solution is sensitive to individual or a few outlier (s) in observation data is conquered because the beam-forming technique is employed for solution instead of the least-squared method. The statistical method used to evaluate uncertainty of the solution based on an assumption that residuals are. in normal distribution, which often gives results without practical significance, is abandoned because grid-searching technique is used in finding solution, which provides a solution set, the eigen-radius of which describes resolution, and the resolution and the standard deviations are organized to evaluate the uncertainty. However, computing efficiency of the TRIT is rather lower than that of Geiger's methods due to the grid-searching process, for example, in this study, about 30s are needed for each process on ordinary desktop computer, but it is a usual solution to change time into accuracy.
- 出版日期2013-4
- 单位中国地震局
