Parameters of finite seismic source model were determined for a set of 36 selected events of the West Bohemia 2000 earthquakes swarm (Ml from 1.7 to 3.0) using stopping phases method. Two stopping phases are generated along the source border where the rupture process terminates and these phases form Hilbert transform pair, which is also the criterion for their identification. Circular and e liptical source models were considered and corresponding source parameters were calculated by inverting interpreted stopping phases delays. As generalization of circular to elliptical model was found to be statistically insignificant, only results related to the circular source including error estimates are presented. Our results are in a good agreement with previously published theoretical formula concerning source radius and magnitude and also fairly well confirm general theoretical assumption about constant stress drop. The determined stress drop ranges between 1 - 10 MPa with the typical value of 2.4 MPa., Petr Kolář and Bohuslav Růžek., and Obsahuje bibliografické odkazy
The West Bohemia earthquake swarm foci are approximated by a circular seismic source model, which radius is assumed to depend only on magnitude of the event. We consider two different models of average slip (i) a constant slip and (ii) a slip exponentially scaled to the magnitude of the event. Based on these assumptions, we stacked the contributions of individual events into representative final fault slip. We processed in such a way four significant swarms recorded during the last three decades in 1986, 1997, 2000 and 2008. Constant slip model indicates final slip was composed of 2 or 3 principal asperities located on one or two different planes. On the contrary, scaled slip model indicates that one big asperity prevails. It is not possible yet to select the preferred slip model. Analysis of the temporal activity of all swarms generally shows three principal phases: starting phase, main phase and fading phase; the upwards trend of activity spreading was observed (slip animation is presented in www supplement http://www.ig.cas.cz/kolar/StopPhase/Asperity). The maximal possible cumulative slip value may have reached the order of meters., Petr Kolář, Bohuslav Růžek, Alena Boušková and Josef Horálek., and Obsahuje bibliografii