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181.
A detailed receiver function image of the sedimentary structure in the Bohai Bay Basin 总被引:5,自引:0,他引:5
Tianyu Zheng 《Physics of the Earth and Planetary Interiors》2005,152(3):129-143
If the site at which receiver functions are constructed is filled by sediments, then the waveforms from these receiver functions are dominantly controlled by the sedimentary structures within the first few seconds after the direct P arrival. Based on this observation, waveform data collected at 44 temporary seismic stations have been used to image the sedimentary structure of the Bohai Bay Basin, a major continental petroliferous basin in Eastern China. An adapted hybrid global waveform inversion method was applied to the receiver functions to extract structural information beneath each of the stations. The derived S-velocity structure provides for the first time, a basin-scale seismic image of detailed sedimentary stratification. The sedimentary cover of the basin is about 2-12 km thick, consisting of Cenozoic, Mesozoic, and Paleozoic strata from top to bottom. The structural features presented in the S-velocity image coincide quite well with the depression-uplift type of tectonic system in the Bohai Bay Basin. The reconstructed morphology of the sedimentary layers provides seismological evidence for the two-stage evolution of the intracontinental basin that were caused by an intensive tectonic regime transition in late Mesozoic immediately following the lithospheric reforming of the Eastern China continent. 相似文献
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Introduction The research on the structure and physical property of ancient hidden hill, igneous rocks and basement is relatively difficult by using seismic data only. If we combine seismic data, magneto-telluric (MT) data and geophysical data together, better results can be obtained for the above problem. A number of geophysicists at home and abroad, such as CHEN and WANG (1990), Siri-punvarapor and Egbert (2000) have tried many methods to solve the problem by the inversion of seismic da… 相似文献
184.
Introduction Ready and Renkin (1971) were the first to make the research on anisotropy problems in magnetotellurics (MT). The progress in the research is not evident because it is more complex and difficult than isotropic problems. Now, the one-dimensional (1D) anisotropy problems in MT have been well solved, while for the two-dimensional (2D) cases, the numerical solutions have only been obtained for some particular conditions (Ready and Renkin, 1975). As to the three-dimensional (3D) ani… 相似文献
185.
2-D crustal Poisson’s ratio from seismic travel time inversion in Changbaishan Tianchi volcanic region 总被引:1,自引:0,他引:1
Based on the inversion method of 2D velocity structure and interface, the crustal velocity structures of P-wave and S-wave
along the profile L
1 are determined simultaneously with deep seismic sounding data in Changbaishan Tianchi volcanic region, and then its Poisson’s
ratio is obtained. Calculated results show that this technique overcomes some defects of traditional forward calculation method,
and it is also very effective to determine Poisson’s ratio distribution of deep seismic sounding profile, especially useful
for study on volcanic magma and crustal fault zone. Study result indicates that there is an abnormally high Poisson’s ratio
body that is about 30 km wide and 12 km high in the low velocity region under Tianchi crater. Its value of Poisson’s ratio
is 8% higher than that of surrounding medium and it should be the magma chamber formed from melted rock with high temperature.
There is a high Poisson’s ratio zone ranging from magma chamber to the top of crust, which may be the uprise passage of hot
substance. The lower part with high Poisson’s ratio, which stretches downward to Moho, is possibly the extrusion way of hot
substance from the uppermost mantle. The conclusions above are consistent with the study results of both tomographic determination
of 3D crustal structure and magnetotelluric survey in this region.
Foundation item: Key Project from China Earthquake Administration and the Project (95-11-02-01) from Ministry of Science and Technology (2001DIA10003).
Contribution No. RCEG200401, Geophysical Exploration Center, China Earthquake Administration. 相似文献
186.
Ji-Hoon Kim Jeongho Lee Tae-Jin Cheong Rak-Hyeon Kim Dong-Chan Koh Jong-Sik Ryu Ho-Wan Chang 《Journal of Hydrology》2005,300(1-4):188-198
The purpose of this study is to apply time series analysis to investigate whether the groundwater quality in the coastal area is affected by the tide. Continuous and regular in situ monitoring data of electrical conductivity (EC) and groundwater level, and tidal level data measured by the National Oceanographic Research Institute were used for the time series analysis. Through the time series analysis, it is known that EC and groundwater level conspicuously fluctuate with two periodicities (15.4 and 0.52-day), which is very similar to those of the tide. Also the behaviors of their fluctuations vary in accordance with the tidal period. These indicate that the groundwater quality has been mainly controlled by the tidal level, and the strength of tidal effect on the groundwater quality is different according to the tidal period. 相似文献
187.
Naohiro Nakamura 《地震工程与结构动力学》2005,34(11):1391-1406
It is important to estimate the influence of layered soil in soil–structure interaction analyses. Although a great number of investigations have been carried out on this subject, there are very few practical methods that do not require complex calculations. In this paper, a simple and practical method for estimating the horizontal dynamic stiffness of a rigid foundation on the surface of multi‐layered soil is proposed. In this method, waves propagating in the soil are traced using the conception of the cone model, and the impulse response function can be calculated directly and easily in the time domain with a good degree of accuracy. The characteristics of the impedance, that is the transformed value to the frequency domain of the obtained impulse response, are studied using two‐ to four‐layered soil models. The cause of the fluctuation of impedance is expressed clearly from its relation to reflected waves from the lower layer boundary in the model. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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