Abstract The delayed signals and external outlier signals are two common outliers which seriously affect the accuracy of microseismic source locating. In order to recognize them efficiently,the hyperbolic and hyperboloidal governing equations were obtained based on the theory of microseismic source locating and the geometrical characteristics of network layout. The source paths from different source location methods were found to be a series of hyperbolas on a plane or hyperboloids in a space;and the shape and the position of hyperbolas or hyperboloids were closely related to the time differences of arrival. The study showed that there were theoretical limits of time differences of arrival for P-wave and delayed wave respectively. A model to derive the two type of theoretical limits of time differences of arrival was established on the analysis of the time differences of arrival and the geometrical characteristics of microseismic network and monitoring space. A table of the time differences of arrival for outlier signals analysis was constructed. A novel method was thus put forward for recognizing the delayed signals and external outlier signals. The feasibility and advantages of this method were verified by an in-situ blasting test. The experimental results show that the delayed signals and external outlier signals are identified correctly and effectively by this novel method. The accuracy of microseismic source location is improved greatly after eliminating the outlier signals.
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Received: 22 August 2013
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