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Calibrating functions for determination of P-wave spectral magnitudes calculated by Duda and Yanovskaya (1994) on the basis of the IASP91 velocity model and the PREM Q-model are verified empirically. For this purpose IRIS broadband records for 120 earthquakes are used, each earthquake having been recorded at about 100 stations. The discrepancies indicate that anelastic absorption assumed in PREM is too high. New calibrating functions are calculated on the basis of the AK135 velocity and anelasticity models (Kennet et al., 1995; Montagner and Kennet, 1996), in which Q in the mantle is higher than in PREM. The verification of the new calibrating functions based on the same observations yields magnitude figures less depending on the epicentral distance. In addition the parameter 2in the Liu-Anderson Q(T) model is estimated, proceeding from the assumption that on the average the radiated spectra comply with the 2-model. The value of 2 was assumed to be 0.1 s in the analysis and its use resulted in the verification of the 2-model for the source spectrum. 相似文献
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T. S. Sakulina Yu. V. Roslov G. A. Pavlenkova 《Izvestiya Physics of the Solid Earth》2009,45(3):231-238
Extensive seismic investigations of the crust and upper mantle have been carried out in the region of the Barents and Kara seas during the past decade. One of the profiles (2-AR) measured by FGU NPP “Sevmorgeo” with the CDP and deep seismic sounding methods was successfully used for comparatively analyzing different technologies of constructing seismic sections and for demonstrating a high information content of the method of mathematical modeling and the constructions of wave sections from supercritical reflected waves. It is shown that the crusts of the North Barents and South Kara basins are different. In the first case, the velocity section changes insignificantly, whereas, in the second case, velocities in the crust increase under the basin and the M boundary rises. The crust of the Novaya Zemlya orogen has a thickness of 48 km, and its average thickness on the profile is 35 km. 相似文献
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Deep seismic investigation across the Barents–Kara region and Novozemelskiy Fold Belt (Arctic Shelf)
Since 1995 SEVMORGEO has collected wide-angle reflection/refraction profiling (WARRP), multichannel seismic data (MCS) and seismoacoustic profiling, along regional lines 1-AR, 2-AR and 3-AR. These lines cross the whole Barents–Kara Region and Novozemelskiy Fold Belt. As a result, new geological data about the deep structure of the Earth's crust have become available. Four main tectono-stratigraphic units are distinguished in the section of the Earth's crust: (1) a sedimentary cover; (2) the Upper Proterozoic (mainly Riphean for the Barents Plate) and Riphean–Paleozoic (the South-Kara Syneclise) deformed and folded complexes; (3) the upper crystalline crust (granite-gneissic metamorphic Archean–Proterozoic complex); (4) the lower crust (basalt complex). The Barents–Kara Region is characterized by moderately thinned continental and subcontinental crust with an average thickness of 37–39 km. On islands and areas of uplifts with ancient massifs, the thickness of the crust (38–42 km) approaches the typical crust for a continental platform. In the Novozemelskiy Fold Belt the thickness of the crust reaches 40–42 km. Rift-related grabens are characterized by significant crustal thinning with thicknesses of 33–36 km. Several grabens are revealed: the Riphean Graben on the Kola-Kanin Monocline, the Lower Paleozoic West-Kola Graben, the Devonian Demidovskiy Aulacogen, the Upper Paleozoic Malyginskiy Graben in the Barents Region and Upper Paleozoic–Triassic Noyabr'skiy and the Chekinskiy grabens in the Kara Region. Data concerning the deep structure lead us to conclude that mainly destructive processes contributed to the dynamics of the forming of the Barents–Kara Region. 相似文献
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V. I. Makarov D. V. Alekseev V. Yu. Batalev E. A. Bataleva I. V. Belyaev V. D. Bragin N. T. Dergunov N. N. Efimova M. G. Leonov L. M. Munirova A. D. Pavlenkin S. Roecker Yu. V. Roslov A. K. Rybin G. G. Shchelochkov 《Geotectonics》2010,44(2):102-126
The results of reflection CMP seismic profiling of the Central Tien Shan in the meridional tract 75–76° E from Lake Song-Köl in Kyrgyzstan to the town of Kashgar in China are considered. The seismic section demonstrating complex heterogeneous structure of the Earth’s crust and reflecting its near-horizontal delamination with vertical and inclined zones of compositional and structural differentiation was constructed from processing of initial data of reflection CMP seismic profiling, earthquake converted-wave method (ECWM), and seismic tomography. The most important is the large zone of underthrusting of the Tarim Massif beneath the Tien Shan. 相似文献
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