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1.
3-D velocity structure in the central-eastern part of Qilianshan 总被引：4，自引：0，他引：4
Introduction The central-eastern part of Qilianshan, located along the northeastern margin of Qing-hai-Xizang (Tibetan) plateau, belongs to the Qilian tectonic zone with active neotectonic move-ment. The main active faults are Haiyuan-Qilian fault, Gulang-Tianjingshan fault and Huang-cheng-Taerzhuang fault. The research area in this paper is a rectangle (Figure 1), the location of the four apex are: A(37.50N, 101.60E), B(36.55N, 103.74E), C(37.20N, 104.20E) and D(38.15N, 102.04E). In… 相似文献
2.
Analytical expressions for the exact 2 × 2 one-way propagator matrix of a plane S wave, propagating along the axis of spirality in the simple 1-D anisotropic simplified twisted crystal model, are presented. The analytical equations are useful in testing the applicability and accuracy of various approximate wavefield modelling methods, especially of the coupling ray theory and of its various quasi-isotropic approximations and various numerical implementations.In addition to the exact analytical solution of the elastodynamic equation in the simplified twisted crystal model, the analytical solutions of the equations of the four ray methods are given. The ray methods are (a) the coupling ray theory, (b) the coupling ray theory with the quasi-isotropic perturbation of travel times, (c) the anisotropic ray theory, (d) the isotropic ray theory. These four approximate solutions of the elastodynamic equation are roughly compared with the exact solution. Both the exact analytical solution and the analytical ray-theory solutions in the simplified twisted crystal model are also helpful in debugging computer codes for various approximate wavefield modelling methods, especially for the coupling ray theory. 相似文献
3.
The exact analytical solution for the plane S-wave, propagating along the axis of spirality in the simple 1-D anisotropic simplified twisted crystal model, is compared with four different approximate ray-theory solutions. The four different ray methods are (a) the coupling ray theory, (b) the coupling ray theory with the quasi-isotropic perturbation of travel times, (c) the anisotropic ray theory, (d) the isotropic ray theory. The comparison is carried out numerically, by evaluating both the exact analytical solution and the analytical solutions of the equations of the four ray methods. The comparison simultaneously demonstrates the limits of applicability of the isotropic and anisotropic ray theories, and the superior accuracy of the coupling ray theory over a broad frequency range. The comparison also shows the possible inaccuracy due to the quasi-isotropic perturbation of travel times in the equations of the coupling ray theory. The coupling ray theory thus should definitely be preferred to the isotropic and anisotropic ray theories, but the quasi-isotropic perturbation of travel times should be avoided. Although the simplified twisted crystal model is designed for testing purposes and has no direct relation to geological structures, the wave-propagation phenomena important in the comparison are similar to those in the models of the geological structures.In additional numerical tests, the exact analytical solution is numerically compared with the finite-difference numerical results, and the analytical solutions of the equations of different ray methods are compared with the corresponding numerical results of 3-D ray-tracing programs developed by the authors of the paper. 相似文献
4.
Introduction Geoscientists concern the explanation of deep focus earthquakes greatly. As a great progress in understanding the formation of deep focus earthquakes, Sung and Burns (1976a, b) proposed that olivine could exist in transition zone in metastable form in the core of some cold subducting slabs, which have got supports from laboratory studies (Rubie, Ross, 1994). Iidaka and Suetsugu (1992) used the seismic data recorded by the dense seismograph networks in Japan to study the travelti… 相似文献
5.
陈伯舫 《地震学报(英文版)》2002,15(5)
Introduction The algorithm of the finite difference method (FDM) for solving the 3-D induction problem used by CHEN (1985) is based on the concept suggested by Brewitt-Taylor and Weaver (1976), which assumes the conductivity to be a smoothly-varying function of position. After the comparisons between many model calculations carried out by the author and other methods showed that the vertical components estimated by our method are acceptable in general cases. However, the reliability of the… 相似文献
6.
Introduction It is found that there are some relationships between the thermal structures of subduction zones and the deep seismicity, while the mechanism relates the thermal structure and the deep seismicity is still unsure (Helffrich, Brodholt, 1991; Furukawa, 1994; Kirby, et al, 1996). From 1980s, geoscientists have constituted a series of numerical simulations on the stress states of subduction slabs. Based on the kinetic computation of Sung and Burns (1976a, b), Goto, et al (1983, 1987… 相似文献
7.
The coupling ray theory bridges the gap between the isotropic and anisotropic ray theories, and is considerably more accurate than the anisotropic ray theory. The coupling ray theory is often approximated by various quasi-isotropic approximations.Commonly used quasi-isotropic approximations of the coupling ray theory are discussed. The exact analytical solution for the plane S wave, propagating along the axis of spirality in the 1-D anisotropic oblique twisted crystal model, is then numerically compared with the coupling ray theory and its three quasi-isotropic approximations. The three quasi-isotropic approximations of the coupling ray theory are (a) the quasi-isotropic projection of the Green tensor, (b) the quasi-isotropic approximation of the Christoffel matrix, (c) the quasi-isotropic perturbation of travel times. The comparison is carried out numerically in the frequency domain, comparing the exact analytical solution with the results of the 3-D ray tracing and coupling ray theory software. In the oblique twisted crystal model, the three studied quasi-isotropic approximations considerably increase the error of the coupling ray theory. Since these three quasi-isotropic approximations do not noticeably simplify the numerical implementation of the coupling ray theory, they should deffinitely be avoided. The common ray approximations of the coupling ray theory do not affect the plane wave, propagating along the axis of spirality in the 1-D oblique twisted crystal model, and should be studied in more complex models. 相似文献
8.
2-D P-wave velocity structure in the mideast segment of Zhangjiakou-Bohai tectonic zone: Anxin-Xianghe-Kuancheng DSS profile 总被引：2，自引：0，他引：2
Introduction The Capital-circle area is the center of politics, economy and culture of China, and manystrong earthquakes occurred here in history. The Zhangjiakou-Bohai tectonic zone located in thearea is an important active zone. In the period of 500 years between AD 1481~1981, 18 earth-quakes with magnitude more than 6 occurred in the area and 11 of them lay in this active tectoniczone. During 1992~2001, continuous GPS observation found sinistral relative movement betweenYanshan Mo… 相似文献
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The inversion of 3-D crustal structure and hypocenter location in the Beijing-Tianjin-Tangshan-Zhangjiakou area by genetic algorithm 总被引：1，自引：0，他引：1
Ｔｈｅｉｎｖｅｒｓｉｏｎｏｆ３┐ＤｃｒｕｓｔａｌｓｔｒｕｃｔｕｒｅａｎｄｈｙｐｏｃｅｎｔｅｒｌｏｃａｔｉｏｎｉｎｔｈｅＢｅｉｊｉｎｇ┐Ｔｉａｎｊｉｎ┐Ｔａｎｇｓｈａｎ┐Ｚｈａｎｇｊｉａｋｏｕａｒｅａｂｙｇｅｎｅｔｉｃａｌｇｏ┐ｒｉｔｈｍＹＯＮＧ－Ｇ... 相似文献
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３ＤｓｔｒｕｃｔｕｒａｌｒｅｃｏｎｓｔｒｕｃｔｉｏｎｏｆＭｏｈｏｉｎｔｈｅＴａｎｇｓｈａｎｅａｒｔｈｑｕａｋｅａｒｅａｂｙｕｓｉｎｇｉｎｖｅｒｓｉｏｎｏｆｃｕｒｖｅｄｉｎｔｅｒｆａｃｅＸＩＡＯＬＩＮＧＬＡＩ（赖晓玲）ＸＩＡＮＫＡＮＧＺＨＡＮＧ... 相似文献
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（胥颐，朱介寿，刘志坚，张华卿，朱燕）３－ＤｖｅｌｏｃｉｔｙｉｍａｇｅｓｏｆｔｈｅｃｒｕｓｔａｎｄｕｐｐｅｒｍａｎｔｌｅｏｆｔｈｅＴｉａｎｓｈａｎａｒｅａ￥ＹｉＸＵ；Ｊｉｅ－ＳｈｏｕＺＨＵ；Ｚｈｉ－ＪｉａｎＬＩＵ；Ｈｕａ－ＱｉｎｇＺＨＡＮＧａｎｄＹａ... 相似文献
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IntroductionSouthwestern China and its adjacent areas studied in the paper is the range of 10(N-36(N, 70(E-110(E, which includes southwestern areas of China (Sichuan, Xizang, Yunnan, Guizhou, Guangxi Provinces, southwestern Shaanxi Province and so on), India, Myanmar, Thailand, Vietnam, Laos and Cambodia countries and oceanic areas of Bay of Bengal and Beibu Gulf. The collision and extrusion of India plate and Eurasia plate makes the geological tectonic complex in this area (Figure 1… 相似文献
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A numerical study of 1-D nonlinear P-wave propagation in solid 总被引：3，自引：0，他引：3
IntroductionBecauseoftheextensivedistributionofruptures,micro-cracksandcrystalfracturesintheearth,therelationshipsbetweenthestressandstrainarenolongerlinear,infact,theyarenonlinear.Inordertoinvestigateandusethenonlinearcharacteristicsofsolidmediumintheearth,weshouldconsidertheinfluenceofnonlinearresponseduringthecourseofseismicmodelingandinversion.Thisisoneoftheimportantstudyfieldsthathavebeenpaidgreatattentionsinthere-centyearsintheworld(Minster,etal,1991;ZHANG,TENG,1993).Thenonlinearchar… 相似文献
15.
D. V. Magritskii 《Water Resources》2011,38(6):709-719
Data of network and expedition measurements and information about water management arrangements were used to study in detail
the peculiarities of along-channel and long-term variations in the major characteristics of suspended sediment runoff in the
lower reach and the delta of the Kuban River. For characteristics periods, the annual volumes of actual and estimated sediment
runoff and the contribution of economic activity in its variations are evaluated and possible changes in sediment runoff characteristics
in the XXI century are forecasted. The specific features, values, and causes of sediment runoff transformation in Kuban delta
in the past and the present are analyzed; sediment balance in the delta is calculated. 相似文献
16.
Ｐｒｅｌｉｍｉｎａｒｙｒｅｓｕｌｔｏｆ３ＤｇｒａｖｉｔａｔｉｏｎａｌｆｏｒｗａｒｄｃａｌｃｕｌａｔｉｏｎｓｔｕｄｙｉｎＢｏｈａｉＳｅａＧＵＡＮＧＸＩＡＬＩＵ１）（刘光夏）ＷＥＮＪＵＮＺＨＡＯ２）（赵文俊）ＷＥＮＪＵＲＥＮ１）（任文菊）ＸＩＵ... 相似文献
17.
The data of the geophysical observation complex at Barentsburg observatory on Spitsbergen archipelago, together with the data from other stations and satellite observations, were used to interpret a sharp increase in the frequency interval in the electromagnetic noise spectral resonance structure (SRS) in the 0.1–10 Hz range that took place during a substorm that occurred on December 24, 2005. It has been shown that such a change in SRS is related to a decrease in the electron density in the ionospheric F region, which agrees with the ionospheric Alfvén resonator theory. In turn, a decrease in electron density is probably related to the fact that the station was in the auroral cavity region related to the field-aligned current flowing into the ionosphere. 相似文献
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Iodine is a trace element playing an important role in vital activities of organisms. It is im-portant for human bodys thyroid gland. Deficient or excessive iodine will not only influence hu-man health but also cause feeblemindedness, so great attention h… 相似文献
20.
Yang Guohua 《中国地震研究》2004,18(2):114-124
Based on high-precision data obtained in the past decade from GPS re-measurement in the North China Network, the Crustal Movement Observation Network of China (CMONOC) and GPS measurement along the Shanxi graben zone, the status and evolution of horizontal crustal movement in the North China region are analyzed. The results show that (1) the Yanshan tectonic zone (Zhangjiakou-Bohai Sea zone)is an active one with the largest horizontal strain in the North China region; The largest tendency differential movement of adjacent blocks is seen between the Yanshan block and the North China plain block; about 2mm/a (left lateral) ; (2)The significant horizontal differential movement along the boundaries of the North China region is characterized by right-lateral strike-slip movement at the middle-north segment on its west boundary (composed of Yinchuan and other active tectonic zones) and compressive movement at the south segment; while the Yinshan rift zone located along the west segment on its north boundary is dominated by tensile movement. Other boundaries and zones have no obvious differential movement; (3) On the whole, measurements of each period differ from one another, which might result from the nonlinear movement component as well as from the error effect. In the paper, results of the relative movement and strain in different periods are given for different blocks and boundary zones. 相似文献