Relative location of microseismic events with multiple masters

Abstract

A recently proposed paraxial ray-based technique for relative location of microseismicity is extended to accommodate several master events with respect to which other events, termed the slaves, are located. The multi-master extension addresses two issues inherent for the existing single-master algorithm: a gradual decrease of its accuracy with the distance from the master and less than satisfactory performance in the presence of strong velocity heterogeneity. Those deficiencies are handled by applying an improved paraxial traveltime formula, exact in homogeneous elliptically anisotropic media, and by distributing masters in the subsurface to sample its heterogeneity. The contributions of different master events to the hypocenter of a given slave are automatically weighted to enhance the influence of adjacent masters, ensuring the precise slave location, and to suppress distant ones, tending to increase the slave-location errors. Tests of the multi-master relative event-location method on synthetic and field microseismic data demonstrate its precision and flexibility as well as applicability to both surface and downhole microseismic geometries.

Method for Identifying and Forecasting Mining-Induced Earthquakes Based on Spatiotemporal Characteristics of Microseismic Activities in Fankou Lead/Zinc Mine

“…At present, more and more mines face a greater risk of mining-induced earthquakes. Although many works that concerning the identification and prediction of rock failures have had a considerable impact on underground mining accidents, only a few focused on mining-induced earthquakes and there is no general method has been developed for the identification and prediction of mining-induced earthquakes so far [21,23,[27][28][29][30][31][32]. Therefore, more studies are required to solve this problem, which sets the scene for this work.…”