During routine processing of selected events of an active KTB experiment it has appeared doubts concerning data reliability and consequently the reliability of results based on them. In the paper 3 events are studied in detail, full seismic moment tensors, as well as their errors, are determined (by non-linear inversion of P/SH waves ratios). It is shown that for the processed low constrained data moment tensor (MT) can be determined, however the relative error is of order of first tens of percent; the results also considerably depend on the way of data picking, used medium model, way of Cost function construction, etc. Any subsequent geophysical interpretation therefore should takes into account this uncertainty. MTs are finally decomposed into DC and non-DC parts, MTs errors are also transformed., Petr Kolář., and Obsahuje bibliografii
Set of events from West Bohemian 2008 seismic swarm with known source mechanisms is processed. The events or their slips respectively are clustered into two groups: (i) principal events with slip laying in the main fault plane and (ii) complementary events deviating from that plane. From those slips we constructed image of slip distribution (a new way of data/slip presentation) and from slip distribution and variations we hypothesized about foci zone properties. Namely, we propose that western block is more rigid and compact; the eastern block appears to be constituted from several sub blocks which can interact with each other during the swarm course. Our hypothesis is supported by similar image constructed from relative rupture velocities, which we consider as independent data. The proposed structural model agrees with the existence of the different observed types of source mechanisms. and Kolář Petr, Boušková Alena.
Formulas for full seismic moment tensor composition are present, i.e. moment tensor is express as a function of ISO, CLVD, DC, strike, dip, rake, where ISO is amount of isotropic part, CLVD is amount of compensated liner-vector dipole and DC is amount of pure double couple. Two forms of final formulas are given: i, two matrixes multiplication, ii, extension of "classical" formulas for 6 independent moment tensor elements., Petr Kolář., and Obsahuje bibliografické odkazy
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
Před více než sto lety Golicyn navrhl postup výpočtu energie zemětřesení. V důsledku použití velmi hrubých dat a aproximací však výsledky obracely kauzalitu příčin a následků zkoumaných jevů. Soudíme, že takovéto příběhy se ve vědě vyskytují opakovaně., Petr Kolář., and Obsahuje bibliografické odkazy
Non-liner inversion of ratio of (relative) P to S waves amplitudes of 3 selected KTB events was performed in Kolář (2007a) to determine moment tensors (MTs). Here further development of the method is presented: (i) re-calibration of the seismograms, (ii) re-interpretation of the S wave maximal amplitudes readings, (iii) a linear inversion of the (re-calibrated) amplitudes including MTs errors determination, and (iv) four methods of transformation of MT errors into errors of their decomposed parts. Generally, the new results confirm previous ones, however remain some open questions about MT errors transformation. New methodology is more accura te and data processing more user-friendly., Petr Kolář., and Obsahuje bibliografické odkazy
We introduce an interactive seismic viewer "OP" (developed in MATLAB platform), primary designated for detailed processing of selected events. Few examples of graphical outlook are presented (main display window, particle motion diagram, etc.), available tools are briefly described, uncommon special tools (simultaneous display of original and filtered signal or time-spatial correlation of seismogram components) are emphasized. Features of the viewer are discussed, some programming solutions are also mentioned., Petr Kolář., and Obsahuje bibliografii