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1.
Using the P-and S-wave arrivals from the 150 earthquakes distributed in Tibetan Plateau and its neighboring areas, recorded
by Tibetan seismic network, Sichuan seismic network, WWSSN and the mobile network situated in Tibetan Plateau, we have obtained
the average P-and S-wave velocity models of the crust and upper mantle for this region:
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, Supp., 573–579, 1992. 相似文献
| (1) | The crust of 70 km average thickness can be divided into two main layers: 16 km thick upper crust with P-wave velocity 5.55 km/s and S-wave velocity 3.25 km/s; and 54 km thick lower crust with P-wave velocity 6.52 km/s and S-wave velocity 3.76 km/s. |
| (2) | The p-wave velocity at the upper most mantle is 7.97 km/s, and the S-wave 4.55 km/s. The low velocity layer in the upper mantle occurs approximately at 140 km deep with a thickness of about 55–62 km. The prominent velocity gradient beneath the LVZ is comparable to the gradient above it. |
2.
Zhong-Yang Lin Hong-Xiang Hu Wen-Bin Zhang Hui-Fen Zhang Zheng-Qin He Zhen-Ming Lin Tao-Xing Qiu 《地震学报(英文版)》1993,6(4):867-881
The preliminary interpretation of Project western Yunnan 86–87 is presented here. It shows that there obviously exists lateral
velocity heterogeneity from south to north in western Yunnan. The depth of Moho increases from 38 km in the southern end of
the profile to 58 km in its northern end. The mean crustal velocity is low in the south, and high in the north, about 6.17–6.45
km/s. The consolidated crust is a 3-layer structure respectively, the upper, middle and lower layer. P
1
0
is a weak interface the upper crust, P
2
0
and P
3
0
are the interfaces of middle-upper crust and middle-lower crust respectively. Another weak interface P
3
0′
can be locally traced in the interior of the lower crust. Interface Pg is 0–6 km deep, interface P
1
0
9.2–16.5 km deep, and interfaces P
2
0
and P
3
0
respectively 17.0–26.5 km, 25.0–38.0 km deep. The velocity of the upper crust gradually increases from the south to the north,
and reaches its maxmium between Nangaozhai and Zhiti, where the velocity of basement plane reaches 6.25–6.35 km/s, then it
becomes small northward. The velocity of the middle crust varies little, the middle crust is a low velocity layer with the
velocity of 6.30 km/s from Jinhe-Erhai fault to the north. The lower crust is a strong gradient layer. There exists respectively
a low velocity layer in the upper mantle between Jinggu and Jingyunqiao, and between Wuliangshan and Lancangjiang fault, the
velocity of Pn is only 7.70–7.80 km/s, it is also low to the north of Honghe fault, about 7.80 km/s. Interface P6/0 can be traced on the top of the upper mantle, its depth is 65 km in the southern end of the profile, and 85 km in the northern
end.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 427–440, 1993. 相似文献
3.
Using the techniques of seismic tomography three-dimensional velocity images at crust and upper mantle in Yunnan province
and its adjacent region have been successfully reconstructed. The results of image are: (1) The image of the velocity in the
upper crust is closely related to the well-known geological structure of the surface, the Kangdian earth axis is a distinct
high velocity area, and a high velocity rock stratum, which appoaching the surface of the earth, has been formed. (2) There
is a low-velocity layer between 26°–31°N and 100°–104°E in deep crust, the depth of Moho discontinuity in Sichuan bass in
is less than 50 km. (3) The results of seismological tomography not only reveal the lateral heterogeneity in the researched
region, but also find approximately the strike of Honghe fault from the image at bottom of crust, and the velocity in both
side of the fault are different obviously. (4) There is a low-velocity column within 25 km to 110 km in Tengchong region,
which may be occured by upward moving of the basalt in the mantle. (5) In studied area, the thickness of the crust in west
part is thicker than in southeast part. (6) From the image at bottom of the crust we can find that earthquakes with magnitude
greater than 5 occurred in big velocity gradient zones, especially in transition zone between high and low velocity. There
are a few earthquake in the low-velocity area. (7) We can see from Figure 6 that there still clearly exists lateral heterogeneity
at 450 depth.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 61–67, 1993. 相似文献
4.
This paper describes synthetically the seismic activity, deep and shallow structures and rock dynamic features in and near
Chaoyang—Yixian region. It is supposed that there is a low velocity layer in middle crust and the three-layered crustal velocities
are all lower than that in both sides of the region. There exists uplifts of upper mantle and asthenosphere-low resistance
layer. It is also studied the composition of matter of three-layered crust, low velocity layer, upper mantle and asthenosphere.
In the end the direct relations between the deep and shallow structure, composition and the seismic activity and new activities
of faults in this region are discussed.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 180–186, 1992. 相似文献
5.
《地震学报(英文版)》1993,6(3):619-629
In the present study the long period surface wave records of 238 wave-paths from 79 earthquakes within China and its adjacent
regions received by 30 seismic network stations are measured by using the improved match-filtering frequency-time analysis
technique and the grid dispersion inversion method to obtain the rayleigh pure-path dispersion values for 147 slant grids
of 4° × 4° in this area, then a three-dimensional shear wave velocity model of the crust and upper mantle beneath south China
area to a depth of 170 km is inversed.
It is found that there are obvious differences among the main structural units, and there are also certain differences among
the subordinate elements even in the individual unit. The crustal thickness of this area is ranging from 30 to 43 km, and
is getting thicker gradually from the east to the west. The average shear velocity of crust is ranging form 3.48 to 3.68 km/s
with the lowest in the northeast part and highest in the west part. No obvious crustal low velocity layer of large scale is
detected. There exist upper mantle low velocity zones in the most of south China area with the starting depth ranging from
75 to 106 km. The lowest shear velocity within the low velocity zones is about 4.28–4.38 km/s. Despite of the existing of
upper mantle low velocity zones beneath the most of south China area, the interfaces between the important layers are quite
clear, the variation of the bedding surfaces is very gentle, and the lateral changes measured in a larger scale of the underground
structure are rather small. It may indicate that the crustal and upper mantle structure of the main part of south China area
belongs to the relatively stable structure of the continental blocks except for the fringe areas such as the fold-faulted
region in the west part and the fault system along the southeastern coast which may belong to the tectonically active area.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 159–167, 1993.
This subject is supported by the National Science Foundation of China. 相似文献
6.
Based on the long period surface wave data recorded by the China Digital Seismograph Network (CDSN), theQ
R
of fundamental mode Rayleigh wave with periods from 10 s to 146 s is determined for the eastern Sino-Korean paraplatform
in this paper. TheQ
β
models of the crust and upper mantle are respectively obtained for the 4 paths, with the aid of stochastic inverse method.
It shows that in the eastern Sino-Korean paraplatform, the average crustalQ
β
is about 200, and that there exists a weak attenuation layer in the middle crust (about 10–20 km deep) which is possibly
related to earthquake-prone layer. A strong attenuation layer (lowQ) of 70 km thick extensively exists in the uppermost mantle, with the buried depth about 80 km. The averageQ
R
of fundamental mode Rayleigh wave is between the value of stable tectonic region and that of active tectonic region, and
much close to the latter.
Contribution No. 96A0001, Institute of Geophysics, SSB, China.
Funded by the Chinese Joint Seismological Science Foundation. 相似文献
7.
ＪｕｄｇｅｍｅｎｔａｎｄｉｎｔｅｒｐｒｅｔａｔｉｏｎｏｆＳｗａｖｅｄａｔａｏｎｔｈｅＢｅｉｊｉｎｇＦｅｎｇｚｈｅｎＤＳＳｐｒｏｆｉｌｅＳＯＮＧＹＡＮＳＯＮＧ（宋松岩）ＸＵＥＳＯＮＧＺＨＯＵ（周雪松）ＸＩＡＮＫＡＮＧＺＨＡＮＧ（张先康）ＳＨ... 相似文献
8.
The phase velocities of Rayleigh waves and the lateral variation of lithospheric structure in Tibetan Plateau 总被引：1，自引：0，他引：1
According to a Sino-U. S. joint project, eleven broadband digital PASSCAL seismometers had been deployed inside the Tibetan
Plateau, of which 7 stations were on the profile from Lhasa to Golmud and other 4 stations situated at Maxin, Yushu, Xigatze
and Linzhi. Dispersions and phase velocities of the Rayleigh surface waves (10s–120s) were obtained on five paths distributed
in the different blocks of Tibetan Plateau. Inversions of the S-wave velocity structures in Songpan-Ganzi block, Qiang-Tang
block, Lhasa block and the faulted rift zone were obtained from the dispersion data. The results show that significant lateral
variation of the S-wave velocity structures among the different blocks exists. The path from Wenquan to Xigatze (abbreviated
as Wndo-Xiga) passes through the rift-zone of Yadong-Anduo. The phase velocities of Rayleigh waves from 10s to 100s on this
path are significantly higher than that on other paths. The calculated mean crustal velocity on this path is 3.8 km/s, much
greater than that on other paths, where mean crustal velocities of 3.4–3.5 km/s are usually observed. Low velocity zones with
different thicknesses and velocities are observed in the middle-lower crust for different paths. Songpan-Ganzi block, located
in the northern part of Tibetan Plateau is characterized by a thinner crust of 65 km thick and a prominent low velocity zone
in the upper mantle. The low velocity zone with a velocity of 4.2 km/s is located at a depth form 115 km to 175 km. While
in other blocks, no low velocity zone in the upper mantle is observed. The value of Sn in Songpan-Ganzi is calculated to be
4.5 km/s, while those in Qiang-Tang and Lhasa blocks are about 4.6 km/s.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, Supp., 566–573, 1992. 相似文献
9.
In this paper, we attempt to use satellite gravity data and a new inversion method to study the lateral density anomaly distribution
in the mantle.
First, density difference Δρ(τ,θ,φ) is expanded in terms of a three—dimensional orthogonal function system, the coefficients of the expansion are to be determined.
Then, a set of observation equations is established from the relationship between density anomaly and disturbing geopotential.
In the equations the unknown vector contains the coefficients of density anomaly expansion, the observational vector is obtained
by computing geopotential perturbations using the potential coefficients of GEM10B, and a filtering process is done for the
observational values by properly selecting the harmonic degrees of geopotentical. Finally, the lateral density variations
in the lower mantle (670 km toCM boundary) are investigated. In this case, the degrees of disturbing geopotential are selected as 2–11, the truncated degrees
of density anomaly expansion are taken asL=6 andK=4, and the damping least squares method is used to solve the observation equations.
The resulting model shows the high level of density perturbations at 670 km discontinuity and core — mantle boundary, a high
— density zone circumscribing the Pacific and a lower—density region under the center of Pacific. These features are in agreement
with the three—dimensional seismic velocity variation features by Dziewonski (1984). In the Antarctic region and some parts
of Atlantic and Indian Ocean, however, the resulting density anomalies are negatively correlated with the seismic velocity
anomalies, the cause resulting in these phenomena is preliminarily analysed in this paper.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 53–65, 1991.
The principle and method represented in this paper can also be suitable to study the lateral density anomaly distribution
in the earth’s crust and the upper mantle. 相似文献
10.
Introduction The gravity anomaly is an indicator of the density distribution of the underground material. Therefore the gravity anomalies have been important data used for studying the deep crustal struc-ture for a long time. Many people have made detailed researches on the regional crustal structure inverted by Bouguer anomalies. In particular some empirical formulae and practical algorithms about the crustal thickness were brought forward, and a series of results were obtained (MENG, 1996)… 相似文献
11.
Preliminary study of crust-upper mantle structure of the Tibetan Plateau by using broadband teleseismic body waveforms 总被引：2，自引：0，他引：2
Lu-Pei Zhu Rong-Sheng Zeng Francis T. Wu Thomas J. Owens George E. Randall 《地震学报(英文版)》1993,6(2):305-316
As part of a joint Sino-U.S. research project to study the deep structure of the Tibetan Plateau, 11 broadband digital seismic
recorders were deployed on the Plateau for one year of passive seismic recording. In this report we use teleseimic P waveforms
to study the seismic velocity structure of crust and upper mantle under three stations by receiver function inversion. The
receiver function is obtained by first rotating two horizontal components of seismic records into radial and tangential components
and then deconvolving the vertical component from them. The receiver function depends only on the structure near the station
because the source and path effects have been removed by the deconvolution. To suppress noise, receiver functions calculated
from events clustered in a small range of back-azimuths and epicentral distances are stacked. Using a matrix formalism describing
the propagation of elastic waves in laterally homogeneous stratified medium, a synthetic receiver function and differential
receiver functions for the parameters in each layer can be calculated to establish a linearized inversion for one-dimensional
velocity structure.
Preliminary results of three stations, Wen-quan, Golmud and Xigatze (Coded as WNDO, TUNL and XIGA), located in central, northern
and southern Plateau are given in this paper. The receiver functions of all three stations show clear P-S converted phases.
The time delays of these converted phases relative to direct P arrivals are: WNDO 7.9s (for NE direction) and 8.3s (for SE
direction), TUNL 8.2s, XIGA 9.0s. Such long time delays indicate the great thickness of crust under the Plateau. The differences
between receiver function of these three station shows the tectonic difference between southern and north-central Plateau.
The waveforms of the receiver functions for WNDO and TUNL are very simple, while the receiver function of XIGA has an additional
midcrustal converted phase. The S wave velocity structures at these three stations are estimated from inversions of the receiver
function. The crustal shear wave velocities at WNDO and TUNL are vertically homogeneous, with value between 3.5–3.6 km/s down
to Moho. This value in the lower crust is lower than the normal value for the lower crust of continents, which is consistent
with the observed strong Sn attenuation in this region. The velocity structure at XIGA shows a velocity discontinuity at depth
of 20 km and high velocity value of 4.0 km/s in the midcrust between 20–30 km depth. Similar results are obtained from a DSS
profile in southern Tibet. The velocity under XIGA decreases below a depth of 30 km, reaching the lowest value of 3.2 km/s
between 50–55 km. depth. This may imply that the Indian crust underthrusts the low part of Tibetan crust in the southern Plateau,
forming a “double crust”. The crustal thickness at each of these sites is: WNDO, 68 km; TUNL, 70 km; XI-GA, 80 km.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, Supp., 581–592, 1992. 相似文献
12.
13.
We model the internal structure of the Moon, initially homogeneous and later differentiated due to partial melting. The chemical
composition and the internal structure of the Moon are retrieved by the Monte-Carlo inversion of the gravity (the mass and
the moment of inertia), seismic (compressional and shear velocities), and petrological (balance equations) data. For the computation
of phase equilibrium relations and physical properties, we have used a method of minimization of the Gibbs free energy combined
with a Mie-Gr@uneisen equation of state within the CaO-FeO-MgO-Al2O3-SiO2 system. The lunar models with a different degree of constraints on the solution are considered. For all models, the geophysically
and geochemically permissible ranges of seismic velocities and concentrations in three mantle zones and the sizes of Fe-10%S
core are estimated. The lunar mantle is chemically stratified; different mantle zones, where orthopyroxene is the dominant
phase, have different concentrations of FeO, Al2O3, and CaO. The silicate portion of the Moon (crust + mantle) may contain 3.5–5.5% Al2O3 and 10.5–12.5% FeO. The chemical boundary between the middle and the lower mantle lies at a depth of 620–750 km. The lunar
models with and without a chemical boundary at a depth of 250–300 km are both possible. The main parameters of the crust,
the mantle, and the core of the Moon are estimated. At the depths of the lower mantle, the P and S velocities range from 7.88 to 8.10 km/s and from 4.40 to 4.55 km/s, respectively. The radius of a Fe-10%S core is 340 ± 30
km. 相似文献
14.
Crust and uppermost mantle structure of the Ailaoshan-Red River fault from receiver function analysis 总被引：5，自引：1，他引：5
XU Mingjie WANG Liangshu LIU Jianhua ZHONG Kai LI Hua HU Dezhao XU Zhen 《中国科学D辑(英文版)》2006,49(10):1043-1052
S-wave velocity structure beneath the Ailaoshan-Red River fault was obtained from receiver functions by using teleseismic body wave records of broadband digital seismic stations. The average crustal thickness, Vp/Vs ratio and Poisson’s ratio were also estimated. The results indicate that the interface of crust and mantle beneath the Ailaoshan-Red River fault is not a sharp velocity discontinuity but a characteristic transition zone. The velocity increases relatively fast at the depth of Moho and then increases slowly in the uppermost mantle. The average crustal thickness across the fault is 36―37 km on the southwest side and 40―42 km on the northeast side, indicating that the fault cuts the crust. The relatively high Poisson’s ratio (0.26―0.28) of the crust implies a high content of mafic materials in the lower crust. Moreover, the lower crust with low velocity could be an ideal position for decoupling between the crust and upper mantle. 相似文献
15.
JIAN PING WU RONG SHENG ZENG YUE HONG MING Institute of Geophysics China Seismological Bureau Beijing China 《地震学报(英文版)》1998,11(6):677-686
ｎｔｒｏｄｕｃｔｉｏｎＴｈｅｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｆｉｎｅｒａｄｉａｌｖｅｌｏｃｉｔｙｓｔｒｕｃｔｕｒｅｏｆｕｐｐｅｒｍａｎｔｌｅｐｌａｙｓａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｉｎｖｅｓｔｉｇａｔｉｏｎｏｆｍａｎｔｌｅｃｏｍｐｏｓｉｔｉｏｎａ... 相似文献
16.
In this paper, the three-dimensional thermal structure and the two-dimensional thermal stress caused by the horizontal inhomogeneity
of the thermal structure in the crust of the Bohai Sea and its surroundings were analyzed using the geothermal and the crust
structural data by means of the finite element method. As resulted, the horizontal distribution of the temperature in the
upper crust is obviously different from that in the lower crust in most part of the region. But the horizontal distribution
of the heat flow is constant in the crust. There is a belt where the thermal structure of the crust is intensely changed around
Tangshan. There are some different characteristics of the thermal stress of the crust around Tangshan, in the North-China
plain, in the Bohai Sea gulf, and in the middle part of the Bohai Sea. Utilizing those results, the distribution features
of the seismic activity in the region were explained in this paper.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 29–35, 1992.
This project is supported by the Chinese Joint Seismological Science Foundation. 相似文献
17.
On the basis of data of long period Rayleigh surface wave, we select 43 two-station paths which cover the eastern China thoroughly. By using the improved method of multi-filtration, we obtain the group velocity and amplitude spectrum, and then get attenuation factor for each paths. We employ Talentola inversion method to get local attenuation factor, and further invert the three-dimension Q β image under the crust and upper mantle in the eastern Chinese continent. The Q β image shows the following basic characters. There is correlation between the seismic activity and Q β structure under the crust and upper mantle in North China region. The Yangtze block begins to collide with and subduct to the North China block from the southern border of the Qinling in the southern Shaanxi. In the large part of Yangtze quasi-platform appear an obvious high Q β area at 88 km deep. In the east of Sichuan depression platform, the juncture of Sichun and Guizhou, and the Jiangnan block near the juncture of Guizhou and Hunan, the lateral variation of Q β in the crust is little, and there is a high-Q β layer no thinner than 40 km in the top mantle. In the Dian-Qian fold and fracture region between Yunnan and Guizhou, the vertical variation of Q β at the region of the crust and upper mantle is little, there is a low-Q β layer in the top mantle, about 40 km thick, low-Q β layer of the upper mantle begins to appear at about 95 km deep. In the east of Yangtze quasi-platform and the central and eastern part of the South China fold system, the Moho is smooth, the lateral variation of Q β in the crust is also little, low-Q β layer of the upper mantle begins to appear at about 85 km deep. 相似文献
18.
Using observational data of geomagnetic total intensity from 13 stations in the Beijing-Tianjin region, 3 stations in the
western Yunnan region of China, and 6 stations in California of U. S. A., the daily variations and their spectra of geomagnetic
total intensity were analyzed and compared. The results show that the morphology, the range and spectrum of daily variations
in geomagnetic total intensity are basically the same within the local extent of 100–200 km and are different in the large
extent of 500 km. The latitude factor of the daily variation range of geomagnetic total intensity is about 1–2 nT/degree within
the latitude extent of 25°–40°.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 83–89, 1992.
This work is supported by the State Seismological Bureau and the Chinese Joint Seismological Science Foundation, and U.S.
Geological Survey. 相似文献
19.
Structure and composition of the continental crust in East China 总被引：14，自引：0，他引：14
Shan Gao Tingchuan Luo Benren Zhang Hongfei Zhang Yinwen Han Zidan Zhao Hartmut Kern 《中国科学D辑(英文版)》1999,42(2):129-140
Crustal structures of nine broad tectonic units in China, except the Tarim craton, are derived from 18 seismic refraction
profiles including 12 geoscience transects. Abundances of 63 major, trace and rare earth elements in the upper crust in East
China are estimated. The estimates are based on sampling of 11 451 individual rock samples over an area of 950 000 km2, from which 905 large composite samples are prepared and analyzed by 13 methods. The middle, lower and total crust compositions
of East China are also estimated from studies of exposed crustal cross sections and granulite xenoliths and by correlation
of seismic data with lithologies. All the tectonic units except the Tarim craton and the Qinling orogen show a four-layered
crustal structure, consisting of the upper, middle, upper lower, and lowermost crusts. P-wave velocities of the bulk lower
crust and total crust are 6.8–7.0 and 6:4–6.5 km/s, respectively. They are slower by 0.2–0.4 km/s than the global averages. The bulk lower crust is suggested to be
intermediate with 58% SiO2 in East China. The results contrast with generally accepted global models of mafic lower crusi. The proposed total crust
composition in East China is also more evolved than previous estimates and characterized by SiO2=64%, a significant negative Eu anomaly (Eu/Eu* = 0.80), deficits in Sr and transition metals, a near-arc magma La/Nd ratio
(3.0), and a calculatedμ(238U/204Pb) value of 5. In addition, it has the following ratios of element pairs exhibiting similar compatibility, which are identical
or close to the primitive mantle values: Zr/Hf=37, Nb/Ta=17.5, Ba/Th=87, K/Pb=0.12x104, Rb/Cs=25, Ba/Rb=8.94, Sn/Sm=0.31, Se/Cd=1.64, La/ As=10.3, Ce/Sb=271, Pb/Bi=57, Rb/TI=177, Er/Ag=52, Cu/Au=3.2×104, Sm/Mo=7.5, Nd/W=40, CI/Li=10.8, F/Nd=21.9, and La/B=1.8.
Project supported by the National Natural Science Foundation of China (Grant Nos. 49625305, 49573183, 49673184, 49794043),
the State Comission of Education, the Ministry of Geology and Mineral Resources of China (Grant No. 850514), the Open Laboratory
of Constitution, Interaction and Dynamics of the Crust-Mantle System, and the Alexander-von-Humboldt Foundation of Germany. 相似文献
20.
Ｓｔｕｄｙｏｎｔｈｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｃｒｕｓｔ┐ｍａｎｔｌｅｔｒａｎｓｉｔｉｏｎｚｏｎｅｉｎＷｅｓｔｅｒｎＹｕｎｎａｎＰｒｏｖｉｎｃｅＨＯＮＧ－ＸＩＡＮＧＨＵ（胡鸿翔）ＺＨＯＮＧ－ＹＡＮＧＬＩＮ（林中洋）ＹＩＮ－ＪＵＢＩＡＮ（边银... 相似文献