Accuracy of the master-event and double-difference locations: synthetic tests and application to seismicity in West Bohemia, Czech Republic
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The relative locations of earthquake hypocentres determined with the master-event (ME) or the double-difference (DD) methods are more accurate and less dispersive compared to the absolute locations. In this paper, we conduct synthetic tests to assess the accuracy of the ME and DD location methods, to study the effects of the control parameters on the locations and possible distortions of the foci geometry. The results indicate that the DD locations are, in general, more accurate than the ME locations and perform significantly better for large earthquake clusters due to their independence of the master event position. The location precision, however, strongly depends on the control parameters used. If the control parameters are optimally chosen, the location errors can be considerably reduced. Moreover, it is proved that no distortion such as artificial clustering of foci is introduced if relative locations are used. Finally, the efficiency of both location methods is exemplified on locations of swarm micro-earthquakes that occurred in the West Bohemia region, Czech Republic, in order to reveal a detailed geometry of the active fault zone.
KeywordsEarthquakes Earthquake swarm Faults Locations Seismicity
We thank two anonymous reviewers for their helpful reviews, Alena Boušková, Josef Horálek and other colleagues from the WEBNET group for providing us with the data from the 2008 swarm activity and for their kind help with pre-processing them, and Pavla Hrubcová for many lively discussions of the subject. The work was supported by the Grant Agency of the Academy of Sciences of the Czech Republic, Grant IAA300120905, by the Grant Agency of the Czech Republic, Grant P210/12/1491, by the Czech Ministry of Education Research Plan, Grant MSM0021620855, by project CzechGeo, Grant LM2010008, and by the European Community's FP7 Consortium Project AIM “Advanced Industrial Microseismic Monitoring”, Grant Agreement 230669.
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