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Doklady Earth Sciences - This paper reports on the results of the seismic studies on the disastrous water-stone flow passing down the Kyngarga River (Republic of Buryatia) on June 27–29,... 相似文献
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V. A. Sankov A. V. Lukhnev A. I. Miroshnitchenko A. A. Dobrynina S. V. Ashurkov L. M. Byzov M. G. Dembelov E. Calais J. Déverchère 《Izvestiya Physics of the Solid Earth》2014,50(6):785-794
The contemporary horizontal movements and deformations in the central and southern parts of the Baikal depression are analyzed, and their relationship with contemporary seismicity is studied. Based on the long-term measurements by the Baikal geodynamical GPS monitoring network, the refined estimate is obtained for the velocity of the divergence of the Siberian and Transbaikalian blocks, which is found to occur in the southeastward direction (130°) at 3.4 ± 0.7 mm per annum. This agrees with the parameters of the long-term extension component estimated from the geological data and with the direction of extension determined from the seismic data. The distribution of the displacement velocity across the strike of the rift, which gradually increases from one block to another, suggests a nonrigid behavior of the continental lithospheric plates at the divergent boundary. About 30% (1.0–1.5 mm per annum) of the total increase in the velocity is accommodated by the Baikal Basin. The strain rate within the trough reaches 3.1 × 10?8 yr?1 and decreases on either side across the structure. The character of distribution of the horizontal displacement velocities on the Baikal divergent boundary between the Eurasian and Amurian plates favors the model of passive rifting. The zones of highly contrasting topography and increased seismicity are localized within the area of contemporary deformations, and the seismic moment release rate directly depends on the strain rate. Here, the rate of the seismic moment release rate makes up a few percent of the geodetic moment accumulation rate calculated by the approach suggested by Anderson (1979). Based on the coherence between the graphs of the rates of geodetic moment accumulation and seismic moment release rate by the earthquakes with M ≥ 5.0 during the historical and instrumental observation periods, the contemporary seismic hazard for the South Baikal Basin could be assessed at a level of seismic event with M = 7.5–7.6. 相似文献
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Dobrynina A. A. Sankov V. A. Chechelnitsky V. V. Tcydypova L. R. German V. I. 《Doklady Earth Sciences》2017,477(2):1494-1497
Doklady Earth Sciences - The results of study of the Hovsgol earthquake with M w = 4.9, which occurred on December 5, 2014, in the northern part of Hovsgol Lake in Mongolia, are presented. An... 相似文献
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Source parameters of the earthquakes of the Baikal rift system 总被引：1，自引：0，他引：1
A. A. Dobrynina 《Izvestiya Physics of the Solid Earth》2009,45(12):1093-1109
The dynamic parameters of the earthquake source—the seismic moment, the moment magnitude, the source radius, the stress drop,
and the amplitude of displacement—are determined by the amplitude Fourier spectra of the body shear waves (S-waves) for 62 earthquakes of the Baikal rift system with the energy class of K
P
= 9.1–15.7. In the calculations I used the classical Brune model. The seismic moment of the earthquakes being investigated
changes from 3.65 × 1011 N m to 1.35 × 1018 N m, and the radii of earthquake sources vary from 390 m to 1.84 km. The values of the drop in stress Δσ grow with an increase
in the seismic moment up to 1.7 × 108 Pa. For the group of weak earthquakes (M
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= 1.7–3.3), extremely low values of the drop in stress 103–104 Pa are observed. The maximum amplitude of displacement in the source amounts to 5.95 m. The empirical equations between the
seismic moment and the other dynamic parameters of the source are determined. The regional dependence of the seismic moment
and energy class is obtained: log M
0 ± 0.60 = 1.03K
P
+ 3.17. The character of the relationship between the seismic moment and the corner frequency indicates that the classical
scaling law of the seismic spectrum for the earthquakes in question is not fulfilled. The obtained estimates of the dynamic
parameters are in satisfactory agreement with the published data concerning the analogous parameters of the other rift zones,
which reflects the general regular patterns of the destruction of the lithosphere and the seismicity in the extension zones
of the lithosphere. 相似文献
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The investigation data on seismic wave attenuation in the lithosphere and upper mantle of the northeastern flank of the Baikal rift system obtained with a seismic coda envelope and sliding window are considered. Eleven local districts were described by one-dimensional attenuation models characterized by alternation of high and low attenuation layers, which are consistent with the results obtained previously by Yu.F. Kopnichev for the southwestern flank of the Baikal rift system [9]. The subcrust of the lithosphere contains a thin layer with high attenuation of seismic waves likely related to higher heterogeneity (fragmentation) and occurrence of fluids. The lithosphere basement depth varies from 100–120 km in the west within the Baikal folded area to 120–140 km in the east within the Siberian Platform. It is concluded that there are two asthenosphere layers. Based on specific features of the lithosphere and upper mantle structure, it can be assumed that they were subject to gradual modification involving fluidization processes and partial melting in the Late Cenozoic extension under the influence of distant tectogenesis sources. 相似文献