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121.
Dynamic faulting under rate-dependent friction 总被引:2,自引:0,他引:2
We discuss the effects of rate-dependent friction on the propagation of seismic rupture on active faults. Several physicists using Burridge and Knopoff's box and spring model of faulting have proposed that fault complexity may arise from the spontaneous development of a self-similar stress distribution on the fault plane. If this model proves to be correct, it has important consequences for the origin of the complexity of seismic sources. In order to test these ideas on a more realistic earthquake model, we developed a new boundary integral equation method for studying rupture propagation along an antiplane fault in the presence of nonlinear rate-dependent friction. We study rupture dynamics of models with single and twin asperities. In our models, asperities are places on the fault with a higher value of prestress. Othewise all fault parameters are homogeneous. We show that for models with such asperities, a slip velocity weakening friction leads to the propagation of supersonic healing phases and to the spontaneous arrest of fracture if the prestress outside the asperities is low enough. For models with asperities, we can also observe narrow slip velocity pulses, qualitatively similar to the so-called Heaton pulses observed in some earthquake accelerograms. We also observe a complex distribution of stress after the rupture that depends on details of the initial distribution of asperities and on the details of the friction law. 相似文献
122.
123.
Modelling magnetization processes in single-and multi-domain rock samples using the preisach diagram
Summary The paper presents the results of identifying a model of the Preisach type for haematite grains of the single-domain as well as multi-domain size. Due to the phenomenological conception of the model, the relations between the parameters of the model and actual parameters are very complex, however, impressive accuracy and stability of the modified model indicate the need to resume studies of this problem. The model parameters also confirm the adequate properties of the vibrating-sample magnetometr (VSM) used and developed in our laboratories. 相似文献
124.
Unkašević Miroslava 《Theoretical and Applied Climatology》1991,44(3-4):223-228
Summary For practical applications both the parent distribution of rainfall intensities and the distribution of their annual maxima are of interest. The relationship between these two distributions cannot be obtained from classical extreme value theory because of seasonal variation and serial correlation in the data. Mathematical results for the distribution of maxima in m-dependent sequences are presented to illustrate the effect of local dependence on the extreme value distribution. The average number of exceedances in a cluster is an important parameter in the relationship between the parent and the extreme value distribution. For 5-min rainfall data from Belgrade, quantiles of the annual maxima are overestimated by about 10 mm h–1 if the effect of serial correlation is ignored. This bias can easily be removed by taking the local clustering of large rainfall intensities in a rainy spell into account.With 4 Figures 相似文献
125.
Summary On the basis of the 1966–73 data, the effect of the difference between pro- and anti-sectors of the IMF is found to be negligible in the winter midlatitude (Central Europe) ionosphere contrary to the dominant effect of this difference in the high-latitude ionosphere found earlier.
a ¶rt;a a 1966–73. u¶rt;m u m amu ¶rt; pro- u anti- mau . na a u ¶rt;um (¶rt; na) u, , a naa a, naum um u.相似文献
126.
127.
The possibility was investigated of carrying out selective flocculation in the model set smithsonite-dolomite using polymers containing nitrogen atoms, which should interact selectively with zinc minerals.A high activity of flocculants in relation to smithsonite and a low activity towards dolomite was observed. However, the activation of the dolomite surface by Zn2+ ions was determined whereby the selective flocculation was not observed in the mixture of smithsonite and dolomite. 相似文献
128.
Dominique Bonnin Georges Calas Hélène Suquet Henri Pezerat 《Physics and Chemistry of Minerals》1985,12(1):55-64
New data on the structure of Garfield nontronite have been produced by the use of different spectroscopic techniques: Mössbauer spectroscopy, optical spectroscopy, X-ray absorption edges and EXAFS and NMR. The tetrahedral iron content is found to be no higher than 1 percent. All iron atoms belong to the octahedral sheet excluding the possibility of the presence of non crystallized phases. Some ambiguities remain about the coherence of the octahedral sheet because of the presence of two doublets in the Mössbauer spectrum and at least two lineshapes in NMR spectra of OH which correspond to different environments. 相似文献
129.
130.
Summary The hypothesis of an expanding Earth is discussed on the basis of lunar laser ranging It is provcd that the given data do not indicate a secular increase in the principal moment of the Earth's inertia which would have to occur if the Earth were really expanding.
¶rt;amunma au u mu u ammuu a¶rt;u u ¶rt;a n a auu . aam, m n mu ¶rt;a m umamu amaua ma uuu u, m ¶rt; nmmam auu, u n¶rt; u m.相似文献