We develop a robust and automatic determination of peak frequencies of direct wave arrivals from microseismic events using mirror image of the recorded signal. These peak frequencies can be then used to evaluate attenuation quality factor (Q). We propose to use procedure that consists of automatic determination of the peak frequencies in combination with matched filter to facilitate selection of suitable events. Using both natural and induced seismicity datasets, we show that matched filter detection along with automatic determination of the peak frequencies gives consistent values of quality factor when compared with manual processing. Proposed technique significantly reduces processing time making it a suitable tool in attenuation analysis of large datasets.
A grant project for the period 2003-2005, supported by the Grant Agency of the Czech Republic, was set up to determine properties of seismic waves and the structure of the uppermost part of the Earth´s crust in the territory of northern Moravia and Silesia. Quarry blasts and mining induced seismic events served as seismic sources. Permanent, temporary and portable seismic stations were used for the monitoring of these seismic events. During the experiments local microearthquakes were also detected and localized. For the complex evaluation of seismic wave features, data of the CELEBRATION 2000 and SUDETES 2003 refraction experiments were incorporated, as well. The velocity-depth dependence of body waves was searched by joint inversions of travel times of Pg/Sg phases. A special feature of the wave trains, generated by quarry blasts, was a pronounced dispersive character of short-period Rayleigh surface waves. These waves enabled us to establish their dispersion curves, on the basis of which the structure of superficial layers was determined down to a depth of several hundreds of meters., Karel Holub, Jaromír Knejzlík, Bohuslav Růžek, Jana Rušajová and Oldřich Novotný., and Obsahuje bibliografii