Complete synthetic seismograms up to 2 Hz for transversely isotropic spherically symmetric media     

Kenji Kawai  Nozomu Takeuchi  Robert J. Geller 《Geophysical Journal International》2006,164(2):411-424

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Parallel 3-D simulation of seismic wave propagation in heterogeneous anisotropic media: a grid method approach   总被引：3，自引：0，他引：3  

Hongwei Gao  Jianfeng Zhang 《Geophysical Journal International》2006,165(3):875-888

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用改进的增量方法计算硫化物中硫的同位素分馏系数     

李永兵  刘建明  胡玉峰  叶杰 《岩石学报》2006,22(2):449-456

增量方法已成功地应用到硅酸盐矿物、金属氧化物、碳酸盐矿物和硫酸盐矿物氧同位素分馏系数的计算中。本文在对硫化物晶体结构与矿物学特点分析的基础上,通过详细分析前人对硅酸盐矿物和金属氧化物中氧同位素分馏的增量计算方法,将氧化物和硫化物的晶体特征加以对比,提出了计算硫化物中硫同位素分馏的增量计算方法。修正的增量方法根据硫化物的晶体化学结构特征,引入了一个重要的参数,即Madelung常数,用于指示不同结构的硫化物对~(34)S的富集能力。本文利用这一修正的增量方法计算出了0℃到1000℃温度范围内,磁黄铁矿、方铅矿、闪锌矿、黄铜矿、硫镉矿的10~3Inβ和它们之间的分馏系数10~3Inα。并给出这五种矿物间的~(34)S富集顺序：磁黄铁矿＞硫镉矿＞闪锌矿＞黄铜矿＞方铅矿。与前人的实验结果对比表明,本次计算结果与实验结果基本吻合。同时,增量计算方法成功地再现了任意硫化物中~(32)S、~(33)S、~(34)S和~(36)S这四种同位素之间确实存在一定的分馏比例关系。这说明尽管增量方法存在一定的局限性,但将其扩展到硫化物间硫同位素分馏的理论计算是可行的。  相似文献   

Heterogeneous formulations of elastodynamic equations and finite-difference schemes     

Ji&#;í Zahradník  Enrico Priolo 《Geophysical Journal International》1995,120(3):663-676

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Simulation of long-period 3-D elastic responses for whole earth models     

Kwi-Hyon Yoon  George A. McMechan 《Geophysical Journal International》1995,120(3):721-730

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Multiple scattering of SH waves in 2-D elastic media with distributed cracks     

Yoshio Murai  Jun Kawahara  Teruo Yamashita 《Geophysical Journal International》1995,122(3):925-937

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Temporal change in scattering and attenuation associated with the earthquake occurrence—A review of recent studies on coda waves     

Haruo Sato 《Pure and Applied Geophysics》1988,126(2-4):465-497

The study of coda waves has recently attracted increasing attention from seismologists. This is due to the fact that it is viewed as a new means by which the stress accumulation stage preceding a large earthquake can be measured, since the scattering paths nearly uniformly cover a fairly large region around the focus and observation stations, compared with the direct ray paths. To date, we have had many reports on the temporal variation of the relation between coda duration and amplitude magnitude, and that of the coda attenuationQ _c ^–1 which is estimated from coda amplitude decay. Some of these have shown a precursor-like behavior; however, others seem to have shown a coseismic change. We have critically reviewed these reports, and discussed what these observational facts tell us about the change in the heterogeneous crust. We found significant temporal variations, not only in the mean but also in the scatter ofQ _c ^–1 , associated with the mainshock occurrence. The formation of new cracks, the reopening and growing of existing cracks, the interaction of these cracks, and the pore water movement through these cracks might correspond to such variations. In addition, we may expect an inhomogeneous distribution of crack clusters in a fairly large region, compared with the aftershock region. The gradual appearance of such crack clusters seems to be the most plausible mechanism by which coda decay gradients are caused to largely scatter in the stress accumulation stage.  相似文献   

Source process of the 14 November 2001 western Kunlun Mountain M _S=8.1 earthquake     

Zhou Yun-hao  Chen Zhang-li  Miao Fa-jun 《地震学报(英文版)》2004,17(1):9-21

Based on digital teleseismic P-wave seismograms recorded by 28 long-period seismograph stations of the global seismic network, source process of the November 14, 2001 western Kunlun Mountain M _S=8.1 (M _W=7.8) earthquake is estimated by a new inversion method. The result shows that the earthquake is a very complex rupture event. The source rupture initiated at the hypocenter (35.95°N, 90.54°E, focal depth 10 km, by USGS NEIC), and propagated to the west at first. Then, in several minutes to a hundred minutes and over a large spatial range, several rupture growth points emerged in succession at the eastern end and in the central part of the finite fault. And then the source rupture propagated from these rupture growth points successively and, finally, stopped in the area within 50 km to the east of the centroid position (35.80°N, 92.91°E, focal depth 15 km, by Harvard CMT). The entire rupture lasted for 142 s, and the source process could be roughly separated into three stages: The first stage started at the 0 s and ended at the 52 s, lasting for 52 s and releasing approximately 24.4% of the total moment; The second stage started at the 55 s and ended at the 113 s, lasting for 58 s and releasing approximately 56.5% of the total moment; The third stage started at the 122 s and ended at the 142 s, lasting for 20 s and releasing approximately 19.1% of the total moment. The length of the ruptured fault plane is about 490 km. The maximum width of the ruptured fault plane is about 45 km. The rupture mainly occurred within 30 km in depth under the surface of the Earth. The average static slip in the underground rocky crust is about 1.2 m with the maximum static slip 3.6 m. The average static stress drop is about 5 MPa with the maximum static stress drop 18 MPa. The maximum static slip and the maximum stress drop occurred in an area within 50 km to the east of the centroid position. Foundation item: Joint Seismological Science Foundation of China (103066) and Foundation of the Seismic Pattern and Digital Seismic Data Application Research Office of Institute of Earthquake Science of the China Earthquake Administration.  相似文献   

Realistic Modeling of Seismic Wave Ground Motion in Beijing City   总被引：5，自引：0，他引：5  

Z. Ding  F. Romanelli  Y. T. Chen  G. F. Panza 《Pure and Applied Geophysics》2004,161(5-6):1093-1106

— Algorithms for the calculation of synthetic seismograms in laterally heterogeneous anelastic media have been applied to model the ground motion in Beijing City. The synthetic signals are compared with the few available seismic recordings (1998, Zhangbei earthquake) and with the distribution of observed macroseismic intensity (1976, Tangshan earthquake). The synthetic three-component seismograms have been computed for the Xiji area and Beijing City. The numerical results show that the thick Tertiary and Quaternary sediments are responsible for the severe amplification of the seismic ground motion. Such a result is well correlated with the abnormally high macroseismic intensity zone in the Xiji area associated with the 1976 Tangshan earthquake as well as with the ground motion recorded in Beijing city in the wake of the 1998 Zhangbei earthquake.  相似文献   

Site-specific Microzonation Study in Delhi Metropolitan City by 2-D Modelling of SH and P-SV Waves   总被引：3，自引：0，他引：3  

Imtiyaz A. Parvez  F. Vaccari  G. F. Panza 《Pure and Applied Geophysics》2004,161(5-6):1165-1184

— Delhi – the capital of India lies on a severe earthquake hazard threat not only from local earthquakes but also from Himalayan events just 200–250 km apart. The seismic ground motion in a part of Delhi City is computed with a hybrid technique based on the modal summation and the finite-difference scheme for site-specific strong ground motion modelling. Complete realistic SH and #E5/E5#-SV wave seismograms are computed along two geological cross sections, (1) north-south, from Inter State Bus Terminal (ISBT) to Sewanagar and (2) east-west, from Tilak Bridge to Punjabi Bagh. Two real earthquake sources of July 15, 1720 (MMI=IX, M=7.4) and August 27, 1960 (M=6.0) have been used in modelling. The response spectra ratio (RSR), i.e. the response spectra computed from the signals synthesized along the laterally varying section and normalized by the response spectra computed from the corresponding signals, synthesized for the bedrock reference regional model, have been determined. As expected, the sedimentary cover causes an increase of the signal amplitude, particularly in the radial and transverse components. To further check the site-effects, we reversed the source location to the other side of the cross section and recomputed the site amplifications. There are only a few sites where a large amplification is invariant with respect to the two source locations considered. The RSR ranges between 5 to 10 in the frequency range from 2.8 to 3.7 Hz for the radial and transverse components of motion along the NS cross section. Along the EW cross section RSR varies between 3.5 to 7.5 in the frequency range from 3.5 to 4.1 Hz. The amplification of the vertical component is considerable at high frequency (>4 Hz.) whereas it is negligible in lower frequency range.  相似文献