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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 117 (1978), S. 816-826 
    ISSN: 1420-9136
    Keywords: Magnitude ; Earthquake magnitude ; Broad-bandP-wave records ; Hokkaido earthquakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A series of Hokkaido events, recorded by the FBV Broadband Seismograph System at the KHC Seismic Station, is used to study the structure of the earthquake magnitude scale on the basis of maximum velocity amplitudesA vmax of teleseismicPwaves in different period bands. Amplitude-periodband (APB) diagrams are constructed for each event. According to the shape of the APB diagrams the events investigated can be divided into three types: (a) events with largestA vmax values in the intermediate period range (periods ofA vmax from 2.2 to 23 sec), (b) events with largestA vmax values in the short-period range (periods ofA vmax from 1 to 2 sec), (c) events exhibiting anomalous APB diagrams. Type (a) events seem to represent the process of wave generation that prevails for shallow earthquakes. Type (b) events approach to explosive-like generation of seismic waves. The nature of the exceptionally occurring type (c) events must be clarified in further investigations. The influence of the type of earthquake on the magnitude values estimated on the basis of standard class A and B (short-period and intermediate-band) seismograms is demonstrated. It appears that for estimating correct values of earthquake magnitudes complementary information on the process of seismic wave generation in the focus is necessary. At teleseismic distances this information can be obtained from either APB diagrams or amplitude spectra ofP waves recorded, e.g., by broadband velocity sensing instruments.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 105 (1991), S. 0 
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The delay-and-sum method by Vinnik (1977) to detect weak PS conversions in the P coda is applied to German, Czechoslovakian and Chinese broadband data. Clear phases (a factor 4-5 above the noise level) are observed in the 3-11 s period band from the 670 and 400 km discontinuities after summing several hundred traces. The decisive step to obtain such a good signal-to-noise ratio was the summation of records from stations in different regions. The summation of a large number (many hundreds) of traces of a single station does not result in similar improvements because of coherent signal-generated noise due to scattering below the station. There are weak indications of a 520 km discontinuity in our data. The delay times relative to P of the converted phases are stable within 1 s between central Europe and China.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics of the Earth and Planetary Interiors 51 (1988), S. 155-156 
    ISSN: 0031-9201
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics of the Earth and Planetary Interiors 18 (1979), S. 58-63 
    ISSN: 0031-9201
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics of the Earth and Planetary Interiors 62 (1990), S. 298-306 
    ISSN: 0031-9201
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Studia geophysica et geodaetica 23 (1979), S. 296-298 
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Резюме Оnuсaны основные naрaмеmры u nрuмененuя aвmомamuческuх щuрокоnолосных сеŭсмuческuх сmaнцuŭ Кaщnерске Горы (ЧССР) u Кщён ж (ПНР), орuенmuровaнных nрuмерно в¶rt;оль меж¶rt;унaро¶rt;но о nрофuля 7 ГСЗ u ор aнuзовaнных в меж¶rt;унaро¶rt;ном соmру¶rt;нuчесmве в рaмкaх nлaнa СЭВ u КАПГ. Полученные нa ¶rt;aнном nрофuле мamерuaлы бу¶rt;уm uсnользованы в основном ¶rt;ля uссле¶rt;овaнuя сmрукmуры лубuнных чaсmеŭ Чещско о Мaссuвa u очa овых мехaнuзмов блuзкuх u лубокuх землеmрясенuŭ.
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  • 7
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Summary The dynamic focal parameters of a series of strong earthquakes, recorded by the FBV broadband velocigraph at KHC (Kašperské Hory, Czechoslovakia), are estimated. The influence of specific wave pattern features on the estimation accuracy is studied. Polarization analysis is used to demonstrate the complicated interference character even of record portions corresponding to a single teleseismic wave group. The values of the dynamic focal parameters do not depend significantly on the length of the analysed record portions and are sufficiently consistent with those reported by Riznichenko [2]. The possibility of estimating dynamic focal parameters from recording of standard classes B (intermediate band) and C (long-period) seismographs is pointed out.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Studia geophysica et geodaetica 28 (1984), S. 67-81 
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Резюме Прове¶rt;ен aнaлuз nере¶rt;amочноŭ функцuu, лuнеŭносmu,грaнuчноŭ чувсmвumельносmu u ¶rt;uнaмuческого ¶rt;uanaзонa общеŭ сеŭсмомеmрuческоŭ сервосuсmемы. Рещaеmся воnрос выборa оnmuмaльноŭ чaсmоmноŭ хaрaкmерuсmuкu сервосuсmемы ¶rt;ля рaзлuчных сеŭсмологuческuх nрuмененuŭ. Пре¶rt;сmaвлен сuнmеmuческuŭ меmо¶rt; nроекmuровaнuя сеŭсмомеmрuческоŭ сервосuсmемы нa основе зa¶rt;aнного рaсnре¶rt;еленuя корнеŭ уnрошенноŭ nере¶rt;amочноŭ функцuu в комnлексноŭ nлоскосmu.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Studia geophysica et geodaetica 44 (2000), S. 251-271 
    ISSN: 1573-1626
    Keywords: local seismic observations ; statistical interpretation ; artificial neural nets ; seismic discrimination ; seismic source mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract We employed multilayer perceptrons (MLP), self organizing feature maps (SOFM), and learning vector quantization (LVQ) to reveal and interpret statistically significant features of different categories of waveform parameter vectors extracted from three-component WEBNET velocigrams. In this contribution we present and discuss in a summarizing manner the results of (i) SOFM classification and MLP discrimination between microearthquakes and explosions on the basis of single-station spectral and amplitude parameter vectors, (ii) SOFM/LVQ recognition of initial onset polarities from PV'-waveforms, and (iii) a source mechanism study of the January 1997 microearthquake swarm based on SOFM classification of combined multi-station PV-onset polarity and SH/PVamplitude ratio (CPA) data. Unsupervised SOFM classification of 497 NKC seismograms revealed that the best discriminants are pure spectral parameter vectors for the recognition of microearthquakes (reliability 95% with 30 spectral parameters), and mixed amplitude and spectral parameter vectors for the recognition of explosions (reliability 98% with 41 amplitude and 30 spectral parameters). The optimal MLP, trained with the standard backpropagation error method by one randomly selected half of a set of 312 mixed (7 amplitude and 7 spectral) single-station (NKC) microearthquake and explosion parameter vectors and tested by the other half-set, and vice versa, correctly classified, on average, 99% of all events. From a set of NKC PV-waveform vectors for 375 events, the optimal LVQ net correctly classified, on average, 98% of all up and 97% of all down onsets, and assigned the likely correct polarity to 85% of the onsets that were visually classified as uncertain. Optimal SOFM architectures categorized the CPA parameter vector sets for 145 January 97 events individually for each of five stations (KOC, KRC, SKC, NKC, LAC) quite unambiguously and stable into three statistically significant classes. The nature of the coincidence of these classes among the stations that provided most reliable mechanism-relevant information (KOC, KRC, SKC) points at the occurence of further seven statistically significant subclassses of mechanisms during the swarm. The ten ‘neural’ classes of focal mechanisms coincide fairly well with those obtained by moment tensor inversion of P and SH polarities and amplitudes extracted from the seismograms interactively. The obtained results, together with those of refined hypocenter location, imply that the focal area consisted of three dominant faults and at least seven subfaults within a volume of not more than 1 km in diameter that likely were seismically activated by vertical stress from underneath.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Studia geophysica et geodaetica 42 (1998), S. 472-499 
    ISSN: 1573-1626
    Keywords: seismograph systems ; calibration responses ; least-squares inversion ; transfer function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The methods and software tools for the identification of the low-frequency portion of seismograph system transfer functions from transient (Dirac or step-impulse) calibration responses and of the high-frequency portion from steady-state (sinusoidal) calibration data are described. The presented procedures allow fast in-site determination of the overall Laplace transfer function of the analog stages of arbitrary seismograph systems. The developed identification software, which may also be employed for determining transfer functions in PAZ (p oles a nd zeros) format from steady-state calibration data given graphically or in the form of FAP (f requency- amplitude-p hase) triplets, has been made publicly available on the INTERNET. The paper is expected to prove useful especially for seismologists faced with the problem of specifying reliable calibration headers for digital upgrades of standard-class analog seismographs, for non-standard feedback-controlled seismograph systems, or for seismometric channels comprising inverse or simulation filters.
    Type of Medium: Electronic Resource
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