Accuracy of the master-event and double-difference locations: synthetic tests and application to seismicity in West Bohemia, Czech Republic
Abstract
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.