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1.
S. S. Arefiev E. A. Rogozhin V. V. Bykova C. Dorbath 《Izvestiya Physics of the Solid Earth》2006,42(1):27-40
The Racha earthquake of 1991 was the strongest of the earthquakes recorded in the Caucasus. It was studied by an international epicentral expedition. Unique data gathered by this expedition included records of aftershocks whose swarm was very intense. A 3-D velocity model is obtained from analysis of these data by the method of local earthquake tomography. The ancient crystalline basement and the sedimentary-volcanic Mesozoic-Cenozoic cover could be identified from cross sections of the P wave field. The eastern and western boundaries of an uplift in the basement of the Dzirulskii Massif are delineated. Linear low velocity heterogeneities correlating with the active Kakheti-Lechkhumi fault zone and two Trans-Caucasian linear fault zones are discovered in the basement. The cloud of aftershock hypocenters is shown to correlate with a reflector coinciding with the cover-basement interface. 相似文献
2.
S. S. Arefiev Zh. Ya. Aptekman V. V. Bykova I. V. Matveev A. G. Mikhin S. G. Molotkov K. G. Pletnev V. V. Pogrebchenko 《Izvestiya Physics of the Solid Earth》2006,42(2):167-177
Results derived from processing of data of field observations in the epicentral zone of the Altai earthquake of 2003 are presented. Accurate location of aftershocks showed that their spatial distribution is in good agreement with the source rupture outcropping on the Earth’s surface. According to aftershock data, the source had a length of 75 km and a maximum width of 20 km and extended in the vertical direction for 17 km; the displacement in the source averaged 2.5 m. Clusters identified in the aftershock cloud define variously dipping planes. The location of hypocenters by regional, national, and global seismic networks is not accurate enough to examine spatial features of the aftershocks. 相似文献
3.
Elena A. Bykova Andrey V. Bobrov Ekaterina A. Sirotkina Luca Bindi Sergey V. Ovsyannikov Leonid S. Dubrovinsky Yuriy A. Litvin 《Physics and Chemistry of Minerals》2014,41(4):267-272
The crystal structure of a knorringite-type compound, Mg3(Cr1.58Mg0.21Si0.21)Si3O12, synthesized in a multi-anvil press at P = 16 GPa and T = 1,600 °C, was refined from single-crystal X-ray diffraction data up to R = 2.36 % for 314 independent reflections. Garnet was found to be cubic and have space group Ia $\overline{3}$ d, with the unit cell parameters a = 11.5718 (1) Å, V = 1,549.54 (2) Å3. The knorringite crystal studied contains 21 mol% of majorite end-member. The structural characterization of knorringitic garnet is important because the study of its thermodynamic constants provides new constraints on thermobarometry of peridotitic garnet assemblages of the lowermost upper mantle. The Raman spectra of synthetic knorringite have been obtained for the first time. 相似文献
4.
The strongest Neftegorsk earthquake, which occurred in 1995 in the northern part of the Sakhalin Island, was studied by the
Epicentral Seismological Expedition, Schmidt Institute of Physics of the Earth, Russian Academy of Sciences. The performed
observations yielded the unique accelerograms of strong aftershocks, which were then applied as a basis for detailed analyses.
The recorded accelerations were in satisfactory compliance with the current ground motion relations. The design spectra developed
on the basis of analyzed records were proposed as an example. The synthetic accelerograms were calculated using the records
of the strongest aftershocks for two modal earthquakes by the empirical Green’s function technique. This technique can be
recommended for practical application as the most physically substantiated method taking into account all regional features. 相似文献
5.
V. I. Mel’nikova N. A. Gileva S. S. Aref’ev V. V. Bykova O. K. Masal’skii 《Izvestiya Physics of the Solid Earth》2012,48(7-8):594-614
The results of investigating the data of stationary and field observations in the epicentral zone of the Kultuk earthquake of August 27, 2008 with M w = 6.3 localized south of Baikal are presented. The seismic activation amounting to 1790 aftershocks with K p ?? 4 (M w ?? 0.9) affected a part of the general fault bounding the southwestern coast of the lake and shallower intrabasin structures. It was established through the cluster analysis that the main shock was located at the periphery of the cloud of the concentrated seismicity component, and three main clusters reflecting a complex character of rupture in the earthquake source were identified in the zone of aftershocks. Owing to a high accuracy of aftershock hypocenters determinations (ERZ ?? 1.2 km), the local character of the seismisity-generating zones was revealed. Based on the method of mapping seismic regime parameters, it was established that zones of reduced fractionality are recognizable in the central part of the source area; in this case, the entire periphery, except for the southeastern direction (where the main shock epicenter is located), is characterized by a high fractionality, which also points to the complex character of the rupture in the source. On the whole, the aftershock sequence under consideration showed the activation of the southwestern flank of the Southern Baikal region, which remained passive for more than one century, and demonstrated destructive features of the Earth??s crust. 相似文献
6.
V. I. Melnikova N. A. Gileva S. S. Arefyev V. V. Bykova A. I. Seredkina 《Izvestiya Physics of the Solid Earth》2013,49(4):563-576
We consider the results of reconstructing the stress-strain state of the Earth’s crust in South Baikal from the focal mechanism data for the Kultuk earthquake of August 27, 2008 (M w = 6.3) and its aftershocks. The source parameters of the main shock were determined by calculating the seismic moment tensor. The focal mechanism solutions of 32 aftershocks (M w ≥ 2.3) were obtained through the deployment of a local seismic network at South Baikal. It is found that the main shock and first aftershocks (August–September) gave rise to the activation of latitudinal fragments of the segmented near-edge fault, and the sources of the consequent aftershocks were dominated by the NW-striking planes related to the small intrabasin structures. The calculations of seismotectonic deformations based on the data on the focal mechanisms of the earthquakes show that the area of activation is dominated by the transtension regime (with deformation in the form of extension with shear). The epicentral and hypocentral fields of the aftershocks and the mechanisms of their sources reflect the complex tectonic structure of the source zone of the Kultuk earthquake, which exhibits a clear subvertical zonality of the local seismically active volume and a wedge-shaped area of crustal destruction. 相似文献
7.
S. S. Arefiev E. A. Rogozhin Zh. Ya. Aptekman V. V. Bykova C. Dorbath 《Izvestiya Physics of the Solid Earth》2006,42(10):850-863
This work generalizes the results of tomographic imaging performed by the authors for epicentral zones. Seismic events in North Africa (the M w = 5.8 earthquake of 1985 near the town of Constantine), eastern Anatolia (the Erzincan M w = 6.7 earthquake of 1992), the Lesser and Greater Caucasus (the 1988 Spitak M w = 6.8 and the 1991 Racha M w = 7.0 earthquakes), and northern Sakhalin (the 1995 Neftegorsk M w = 7.1 earthquake) are examined. It is shown how various morphokinematic types of active faults differ in the resulting tomographic images at various depths. A classification of tomographic images of strong earthquake source zones is proposed in accordance with the rank of their generating faults. The sources of the Spitak, Racha, and Erzincan earthquakes are confined to large boundary faults separating tectonic zones. Lower velocity bands are revealed in the tomographic images, and low velocity “pockets” 1–2 km or somewhat more in width penetrating to a depth of up to 15 km are observed near the fault zones. The Constantine and Neftegorsk earthquakes were generated by faults of a lower rank. The source zones of these events are imaged tomographically as narrow gradient zones. 相似文献
8.
A.?V.?KalininaEmail author S.?M.?Ammosov V.?V.?Bykova R.?E.?Tatevossian 《Seismic Instruments》2018,54(4):499-513
The effect of the upper part of a layered profile on calculated seismic hazard parameters is analyzed. The behavior of the soil profile is studied as part of equivalent linear modeling with the example of six seismogeological models. Peak ground acceleration of the input signal varies from 0.1 to 0.6 g. It is shown that the character of the dependence of physicomechanical properties in the layer on the strain value leads to variations in the amplitudes of the response spectrum on the free surface and displacement of the maximum of the frequency spectrum. An increase in the thickness of the upper layer significantly influences the shape of the response spectra. Variations in the PGA values, damping coefficients, strain values with depth are calculated, as well as the velocity profiles for different soil layers with respect to the degradation curves. It is demonstrated that restricting the upper limit of the damping coefficient to 15% does not lead to noticeable changes in the shape of the response spectra on the free surface. The soil column begins to decrease the peak value of the input signal when its level exceeds 0.3 g. 相似文献
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10.
R. N. Vakarchuk R. E. Tatevossian Zh. Ya. Aptekman V. V. Bykova 《Izvestiya Physics of the Solid Earth》2013,49(5):653-659
The source of the 1991 Racha earthquake in the Greater Caucasus generally corresponds to thrusting, which is characteristic of the predominant regional compression stress field. A more adequate view of the rupture process is provided by a complex source model composed of three subsources. This model is reconstructed by the body-wave inversion and consistent with the spatial distribution of the aftershocks. In terms of the suggested model, at the last stage of the rupture process, the opposite slip type (normal faulting) is observed in the source, which seems to be objective. It compensates the rapid (probably short) local redistribution of stresses caused by the thrusts in the first two subsources. The surface deformations observed in the epicentral zones of strong earthquakes are probably the analogs of such a compensative mechanism. For example, in the rear parts of the thrusts associated with the surface ruptures, normal faults trending parallel to the strike of the thrust line occur. Another analog of the compensative motion is probably the peculiarities of the aftershock sources. It has long since been noted (Kuznetsova et al., 1976) that some fault plane solutions in the aftershock sequences of strong earthquakes are close to the main shock solution, while others are different. The explanation of this phenomenon is suggested in (Kuznetsova et al., 1976; Kostrov and Das, 1988). In (Kuznetsova et al., 1976), these events are referred to as the aftershocks due to the fracture growth and aftershocks of relaxation, respectively. 相似文献