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Three dimensional shear wave velocity structure of crust and upper mantle in South China Sea and its adjacent regions by surface waveform inversion 被引量:22
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作者 曹小林 朱介寿 +2 位作者 赵连锋 曹家敏 洪学海 《地震学报》 CSCD 北大核心 2001年第2期113-124,共12页
We assembled approximately 328 seismic records. The data set was from 4 digitally recording long-period and broadband stations of CDSN. We carried out the inversion based on the partitioned waveform inversion (PWI). I... We assembled approximately 328 seismic records. The data set was from 4 digitally recording long-period and broadband stations of CDSN. We carried out the inversion based on the partitioned waveform inversion (PWI). It partitions the large-scale optimization problem into a number of independent small-scale problems. We adopted surface waveform inversion with an equal block (2((2() discretization in order to acquire the images of shear velocity structure at different depths (from surface to 430 km) in the crust and upper-mantle. The resolution of all these anomalies has been established with (check-board( resolution tests. These results show significant difference in velocity, lithosphere and asthenosphere structure between South China Sea and its adjacent regions. 展开更多
关键词 面波波形 分块波形反演 三维S波速度结构 中国数字地震台网 “检验板”法 岩石圈
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Shear wave velocity model using HVSR inversion beneath Bandar Lampung City
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作者 Ahmad Zaenudin Alhada Farduwin +1 位作者 Gede I Boy Darmawan Karyanto 《Earthquake Science》 2024年第4期337-351,共15页
The horizontal-to-vertical spectral ratio(HVSR)method has been used to characterize site-effect parameters that are indispensable in seismic hazard and risk-reduction studies in urban areas and rapid land-use planning... The horizontal-to-vertical spectral ratio(HVSR)method has been used to characterize site-effect parameters that are indispensable in seismic hazard and risk-reduction studies in urban areas and rapid land-use planning.This method is widely used because it is the cheapest and simplest geophysical method for the acquisition and processing stages.In subsequent developments,the HVSR method has been widely used to determine elastic rock parameters,particularly shear wave velocity(v_(S)),through the HVSR curve inversion process.Furthermore,the v_(S)structural model can be used to delineate the presence of complex geological structures,particularly faults and sedimentary basins.Bandar Lampung is a city in Lampung Province with many fault structures and groundwater basins to the south.There are 83 HVSR measurement points around Bandar Lampung for delineating the presence of fault structures and groundwater basins.We produced the HVSR curve from the measurement results and then performed an inversion process using the particle swarm optimization algorithm to obtain v_(S)for the depth profile.Subsequently,from this profile,we produced a two-dimensional(2D)lateral and vertical model.The mean v_(S)value was calculated from all the measurement points,and we found stiff soil layers reaching depths of approximately 5 m,with a value of v_(S)<330 m/s.A bedrock layer with a velocity exceeding 1250 m/s was visible at a depth of 100 m.Based on the 2D model,the v_(S)structure shows that the city of Bandar Lampung is divided into two zones,with a NW-SE boundary.The north-middle-eastern part of the city consists of harder rocks.This harder rock is characterized by extremely high v_(S)values,starting from a depth of 50 m.In contrast,the south-middle-west exhibits a low-moderate v_(S)anomaly associated with groundwater basins SW of the city.From the 2D v_(S)structural model,fault structures can be found along the city,characterized by a contrast of v_(S)values from low to medium and from medium to high. 展开更多
关键词 shear wave velocity HVSR fault structures groundwater basin Bandar Lampung City
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The Effectiveness of Shallow Surface Geophysical Methods in Shear Wave Velocity Derivation
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作者 Dewan Mohammad Enamul Haque A. S. M. Woobaidullah 《Journal of Civil Engineering and Architecture》 2018年第8期573-585,共13页
Shear wave velocity Vs is measured by the surface geophysical survey like MASW (multi-channel surface wave analysis) or RWM (refraction wave method) and by the subsurface method like PS logging. PS logging and RWM... Shear wave velocity Vs is measured by the surface geophysical survey like MASW (multi-channel surface wave analysis) or RWM (refraction wave method) and by the subsurface method like PS logging. PS logging and RWM are direct methods to derive shear wave velocity and MASW retrieves shear wave through the inversion of the surface wave. In this work, the effectiveness of surface methods (MASW and RWM) is compared with PS logging in determining shear wave velocity. For this purpose, shear wave velocity results Vs30 of 12 PS logging and MASW surveys conducted in Mymensingh Municipality in Bangladesh have been utilized. Additionally, the shear wave velocity results of three PS logging have been compared with the refraction profiles of RWM survey conducted in Rooppur nuclear power plant site in Bangladesh. The relative discrepancy between RWM and PS logging is found less (ranges from -3.92 to 0.93) compared to MASW and PS logging (+/-0.88 to 33.92). The correlation coefficient of Vs30 derived from RWM and PS logging is observed much better (0.60) compared to MASW and PS logging (0.40). The result is good considering the lateral lithologic variability and inherent differences among techniques. It is evident from the comparison that the RWM can be used as a cost-effective alternative to traditional borehole PS logging method for Vs30 determination and thus the number of down-hole logging tests might be significantly reduced. 展开更多
关键词 shear wave velocity surface wave velocity shallow seismic survey inversion.
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Middle and upper crust shear-wave velocity structure of the Chinese mainland
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作者 冯梅 安美建 《Acta Seismologica Sinica(English Edition)》 CSCD 2007年第4期359-369,共11页
In order to give a more reliable shallow crust model for the Chinese mainland, the present study collected many short-period surface wave data which are better sensitive to shallow earth structures. Different from tra... In order to give a more reliable shallow crust model for the Chinese mainland, the present study collected many short-period surface wave data which are better sensitive to shallow earth structures. Different from traditional two-step surface wave tomography, we developed a new linearized surface wave dispersion inversion method to directly get a 3D S-wave velocity model in the second step instead of inverting for 1D S-velocity profile cell by cell. We convert all the regionalized dispersions into linear constraints for a 3D S-velocity model. Checkerboard tests show that this method can give reasonable results. The distribution of the middle- and upper-crust shear-wave velocity of the Chinese mainland in our model is strongly heterogeneous and related to different geotectonic terrains. Low-velocity anomalies delineated very well most of the major sedimentary basins of China. And the variation of velocities at different depths gives an indication of basement depth of the basins. The western Tethyan tectonic domain (on the west of the 95°E longitude) is characterized by low velocity, while the eastern Tethyan domain does not show obvious low velocity. Since petroleum resources often distribute in sedimentary basins where low-velocity anomaly appears, the low velocity anomalies in the western Tethyan domain may indicate a better petroleum prospect than in its eastern counterpart. Besides, low velocity anomaly in the western Tethyan domain and around the Xing'an orogenic belt may be partly caused by high crustal temperature. The weak low-velocity belt along -105°E longitude corresponds to the N-S strong seismic belt of central China. 展开更多
关键词 surface-wave tomography shear-wave velocity sedimentary basins shallow crust China
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Research on the Relationship between Shallow Shear Wave Velocity and Basement Structure in the Tianjin Coastal Area
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作者 Gao Wuping Chen Yukun +3 位作者 Ren Feng Yan Chengguo Wang Zhisheng Yang Fei 《Earthquake Research in China》 2012年第4期512-519,共8页
Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0. ... Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0. 01° x 0. 01°x lm grid. A shallow 3-D shear wave velocity structure of Tianjin coastal area is obtained. According to the data and geological background, we selected two typical velocity profiles to try to introduce and explain its relationship to basement structure. The results show that the shear wave velocity structure clearly presents the characteristic of stratification and lateral inhomogeneity. Furthermore, the difference of the shear wave structure between tectonic elements is clear and the velocity structure between the two sides of the local or border fault in the Quaternary is disturbed or affected significantly. It intuitively shows that the basement structure and fault activity of this region had good control of sedimentation development and strata formation in the Quaternary period which would have an important effect on engineering seismic and geological condition evaluation. 展开更多
关键词 shear wave velocity Transverse wave well logging Tianjin coastal area velocity structure Tectonic element Fault QUATERNARY
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Imaging shallow structure with active-source surface wave signal recorded by distributed acoustic sensing arrays 被引量:6
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作者 Zhenghong Song Xiangfang Zeng +2 位作者 Clifford H.Thurber Hebert F.Wang Dante Fratta 《Earthquake Science》 CSCD 2018年第4期208-214,共7页
Distributed acoustic sensing(DAS) is one recently developed seismic acquisition technique that is based on fiber-optic sensing. DAS provides dense spatial spacing that is useful to image shallow structure with surface... Distributed acoustic sensing(DAS) is one recently developed seismic acquisition technique that is based on fiber-optic sensing. DAS provides dense spatial spacing that is useful to image shallow structure with surface waves.To test the feasibility of DAS in shallow structure imaging,the PoroTomo team conducted a DAS experiment with the vibroseis truck T-Rex in Brady’s Hot Springs, Nevada, USA.The Rayleigh waves excited by the vertical mode of the vibroseis truck were analyzed with the Multichannel Analysis of Surface Waves(MASW) method. Phase velocities between5 and 20 Hz were successfully extracted for one segment of cable and were employed to build a shear-wave velocity model for the top 50 meters. The dispersion curves obtained with DAS agree well with the ones extracted from co-located geophones data and from the passive source Noise Correlation Functions(NCF). Comparing to the co-located geophone array, the higher sensor density that DAS arrays provides help reducing aliasing in dispersion analysis, and separating different surface wave modes. This study demonstrates the feasibility and advantage of DAS in imaging shallow structure with surface waves. 展开更多
关键词 distributed acoustic sensing surface wave multiple channel analysis shallow structure
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PROPAGATION OF SURFACE ACOUSTIC WAVES IN PRESTRESSED ANISOTROPIC LAYERED PIEZOELECTRIC STRUCTURES 被引量:5
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作者 Liu Hua Kuang Zhenbang +2 位作者 Cai Zhengming Wang Tiejun Wang Zikun 《Acta Mechanica Solida Sinica》 SCIE EI 2003年第1期16-23,共8页
The propagation of surface acoustic waves in layered piezoelectric structureswith initial stresses is investigated. The phase velocity equations are obtained for electricallyfree and shorted cases, respectively. Effec... The propagation of surface acoustic waves in layered piezoelectric structureswith initial stresses is investigated. The phase velocity equations are obtained for electricallyfree and shorted cases, respectively. Effects of the initial stresses on the phase velocity and theelectromechanical coupling coefficient for the fundamental mode of the layered piezoelectricstructures are discussed. Numerical results for the c-axis oriented film of LiNbO_3 on a sapphiresubstrate are given. It is found that the fractional change in phase velocity is a linear functionwith the initial stresses, and the electromechanical coupling factor increases with an increase ofthe absolute values of the compressive initial stresses. The results are useful for the design ofsurface acoustic wave devices. 展开更多
关键词 surface acoustic waves layered piezoelectric structure phase velocity electromechanical coupling coefficient
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CRUST AND UPPER STRUCTURE OF QINGHAI-TIBET PLATEAU AND ITS ADJACENT REGIONS FROM SURFACE WAVEFORM INVERSION
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作者 Cao Xiaolin,Cao Jamin,Zhu Jieshou 《地学前缘》 EI CAS CSCD 2000年第S1期316-316,共1页
In this paper,218 long period Rayleigh wave records from 7 seismic station of CDSN are selected.We applied a partitioned waveform inversion to these data in order to construct a 3\|D model of shear velocity down to 40... In this paper,218 long period Rayleigh wave records from 7 seismic station of CDSN are selected.We applied a partitioned waveform inversion to these data in order to construct a 3\|D model of shear velocity down to 400km depth in the crust and upper mantle of Qinghai\|Tibet plateau and Its Adjacent Regions (22°~44°N,70°~110°E).The first step of the waveform inversion used involved the matching of the waveforms of fundamental and highermost Ravleigh waves with waveforms synthesized from stratified models;in the second stage,the 3\|D model was constructed by solve linear constrains equation. The major structural features inferred from the surface waveform inversions can be summarized as follows:(1) There is a great contrast between surface waveform through Qinghai—Thibet plateau and the others.Main frequency of the former is lower than the latter, which indicate the crust depth of Qinghai—Tibet plateau is deeper than the others. In addition,the amplitude of about 30s period and 50s period is lower than both sides,which implied these exist lower velocity layer at about 25km depth and about 50km depth in Qinghai—Tibet plateau Crust.The former is common,the latter was argued because resolution of most method can not prove it. 展开更多
关键词 Qinghai—Tibet plateau long period Rayleigh wave partitioned waveform inversion 3\|D model of shear velocity lower velocity layer LITHOSPHERE structure
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Crustal thickness,V_(P)/V_(S) ratio,and shear wave velocity structures beneath Myanmar and their tectonic implications
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作者 Lay Nwe Zigen Wei +3 位作者 Zhiwei Li Feng Bao Xuelei Li Jintao Hu 《Earthquake Research Advances》 CSCD 2022年第1期15-21,共7页
The crustal structure in Myanmar can provide valuable information for the eastern margin of the ongoing IndoEurasian collision system.We successively performed H-k stacking of the receiver function and joint inversion... The crustal structure in Myanmar can provide valuable information for the eastern margin of the ongoing IndoEurasian collision system.We successively performed H-k stacking of the receiver function and joint inversion of the receiver function and surface wave dispersion to invert the crustal thickness(H),shear wave velocity(V_(S)),and the V_(P)/V_(S) ratio(k)beneath nine permanent seismic stations in Myanmar.H was found to increase from 26 km in the south and east of the study area to 51 km in the north and west,and the V_(P)/V_(S) ratio was complex and high.Striking differences in the crust were observed for different tectonic areas.In the Indo-Burma Range,the thick crust(H~51 km)and lower velocities may be related to the accretionary wedge from the Indian Plate.In the Central Myanmar Basin,the thin crust(H=26.9-35.5 km)and complex V_(P)/V_(S) ratio and V_(S) suggest extensional tectonics.In the Eastern Shan Plateau,the relatively thick crust and normal V_(P)/V_(S) ratio are consistent with its location along the western edge of the rigid Sunda Block. 展开更多
关键词 Myanmar Crustal thickness VP/VSratio shear wave velocity Receiver function surface wave dispersion
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Shear wave velocity-based liquefaction evaluation in the great Wenchuan earthquake: a preliminary case study 被引量:9
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作者 Zhou Yanguo,Chen Yunmin and Ling Daosheng MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering,Institute of Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China Assistant Professor Professor 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2009年第2期231-239,共9页
The great Wenchuan earthquake (Ms= 8.0) in 2008 caused severe damage in the western part of the Chengdu Plain. Soil liquefaction was one of the major causes of damage in the plain areas, and proper evaluation of liq... The great Wenchuan earthquake (Ms= 8.0) in 2008 caused severe damage in the western part of the Chengdu Plain. Soil liquefaction was one of the major causes of damage in the plain areas, and proper evaluation of liquefaction potential is important in the definition of the seismic hazard facing a given region and post-earthquake reconstruction. In this paper, a simplified procedure is proposed for liquefaction assessment of sandy deposits using shear wave velocity (V), and soil liquefaction from the Banqiao School site was preliminarily investigated after the earthquake. Boreholes were made at the site and shear wave velocities were measured both by SASW and down-hole methods. Based on the in-situ soil information and V profiles, the liquefaction potential of this site was evaluated. The results are reasonably consistent with the actual field behavior observed after the earthquake, indicating that the proposed procedure is effective. The possible effects of gravel and fines contents on liquefaction of sandy soils were also briefly discussed. 展开更多
关键词 LIQUEFACTION Wenchuan earthquake shear wave velocity spectral analysis of surface waves (SASW) hazarddefinition
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Application of active-source surface waves in urban underground space detection: A case study of Rongcheng County, Hebei, China 被引量:1
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作者 GuangWen Wang HaiYan Wang +3 位作者 HongQiang Li ZhanWu Lu WenHui Li TaiRan Xu 《Earth and Planetary Physics》 EI CSCD 2022年第4期385-398,共14页
Active-source surface wave exploration is advantageous because it has high imaging accuracy,is not affected by high-speed layers,and has a low cost;thus,it has unique advantages for investigating shallow surface struc... Active-source surface wave exploration is advantageous because it has high imaging accuracy,is not affected by high-speed layers,and has a low cost;thus,it has unique advantages for investigating shallow surface structures.For the development and utilization of urban underground space,two parameters in the shallow surface are important,namely,the shear wave velocity(V_(S))and the predominant period of the site,which determine the elevation and aseismic grade of the building design.The traditional method is mainly to obtain the two above-mentioned parameters through testing and measuring drilling samples.However,this method is extremely expensive and time consuming.Therefore,in this research,we used the multichannel surface wave acquisition method to extract the fundamental dispersion curve of single-shot data by using the phase shift method and obtain the V_(S) characteristics in the uppermost 40 m by inversion.We arrived at the following two conclusions based on the V_(S) profile.First,the study area can be roughly divided into five layers,among which the layers 0−8 m,14−20 m,and 20−30 m are low-velocity layers,corresponding to miscellaneous fill,a water-bearing sand layer,and a sand layer;therefore,the V_(S) is relatively low.In contrast,the layers at 8−14 m and 30−40 m are high-velocity layers that are mainly composed of clay,with a relatively better compactness and relatively high V_(S) values.In addition,a low-speed anomaly appears abruptly in the high-speed area at 20−40 m.This anomaly,when combined with geological data,suggests that it is an ancient river channel.Second,from the V_(S) value,the V_(Se)(equivalent shear wave velocity)was calculated.The construction site soil was categorized as class III,with good conditions for engineering geology.In addition,we calculated the predominant period of the site to be 0.56-0.77 s based on the V_(S).Therefore,in the overall structural design of the foundation engineering,the natural vibration period of the structure should be strictly controlled to avoid the predominant period of the site. 展开更多
关键词 Jizhong depression surface wave exploration shallow structure site category predominant period
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Crustal velocity structures beneath North China revealed by ambient noise tomography 被引量:7
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作者 Lihua Fang Jianping Wu +2 位作者 Zhifeng Ding Weilai Wang Giuliano Francesco Panza 《Earthquake Science》 CSCD 2010年第5期477-486,共10页
We collected continuous noise waveform data from January 2007 to February 2008 recorded by 190 broadband and 10 very broadband stations of the North China Seismic Array. The study region is divided into grid with inte... We collected continuous noise waveform data from January 2007 to February 2008 recorded by 190 broadband and 10 very broadband stations of the North China Seismic Array. The study region is divided into grid with interval 0.25°×0.25°, and group velocity distribution maps between 4 s and 30 s are obtained using ambient noise tomography method. The lateral resolution is estimated to be 20-50 km for most of the study area. We construct a 3-D S wave velocity model by inverting the pure path dispersion curve at each grid using a genetic algorithm with smoothing constraint. The crustal structure observed in the model includes sedimentary basins such as North China basin, Yanqing-Huailai basin and Datong basin. A well-defined low velocity zone is observed in the Beijing-Tianjin-Tangshan region in 22-30 km depth range, which may be related to the upwelling of hot mantle material. The high velocity zone near Datong, Shuozhou and Qingshuihe within the depth range of 1-23 km reveals stable characteristics of Ordos block. The Taihangshan front fault extends to 12 km depth at least. 展开更多
关键词 seismic noise surface wave tomography velocity structure genetic algorithm North China
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Smooth constraint inversion technique in genetic algorithms and its application to surface wave study in the Tibetan Plateau 被引量:3
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作者 吴建平 明跃红 曾融生 《Acta Seismologica Sinica(English Edition)》 EI CSCD 2001年第1期49-57,共9页
Smooth constraint is important in linear inversion, but it is difficult to apply directly to model parameters in genetic algorithms. If the model parameters are smoothed in iteration, the diversity of models will be g... Smooth constraint is important in linear inversion, but it is difficult to apply directly to model parameters in genetic algorithms. If the model parameters are smoothed in iteration, the diversity of models will be greatly suppressed and all the models in population will tend to equal in a few iterations, so the optimal solution meeting requirement can not be obtained. In this paper, an indirect smooth constraint technique is introduced to genetic inversion. In this method, the new models produced in iteration are smoothed, then used as theoretical models in calculation of misfit function, but in process of iteration only the original models are used in order to keep the diversity of models. The technique is effective in inversion of surface wave and receiver function. Using this technique, we invert the phase velocity of Raleigh wave in the Tibetan Plateau, revealing the horizontal variation of S wave velocity structure near the center of the Tibetan Plateau. The results show that the S wave velocity in the north is relatively lower than that in the south. For most paths there is a lower velocity zone with 12-25 km thick at the depth of 15-40 km. The lower velocity zone in upper mantle is located below the depth of 100 km, and the thickness is usually 40-80 km, but for a few paths reach to 100 km thick. Among the area of Ando, Maqi and Ushu stations, there is an obvious lower velocity zone with the lowest velocity of 4.2-4.3 km/s at the depth of 90-230 km. Based on the S wave velocity structures of different paths and former data, we infer that the subduction of the Indian Plate is delimited nearby the Yarlung Zangbo suture zone. 展开更多
关键词 genetic algorithm smooth constraint surface wave S wave velocity structure Tibetan Plateau
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3D Velocity Structure and Its Tectonic Implications in the East China Sea and Yellow Sea 被引量:1
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作者 Feng Rui, Zhou Hainan, Institute of Geophysics, State Seismological Bureau, Beijing Yao Zhengsheng, Seismological Institute of Lanzhou, Lanzhou Ma Guiming and Li Quanlin Institute of Geophysics, State Seismological Bureau Beijing Fei Zhenbi 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1993年第3期273-296,共24页
3D structure of the crust and upper mantle in the studied area has been analyzed from surface wave tomography. The velocity distribution in the uppermost crust is symmetrical on two sides of the central line of the se... 3D structure of the crust and upper mantle in the studied area has been analyzed from surface wave tomography. The velocity distribution in the uppermost crust is symmetrical on two sides of the central line of the sea, and coincides with the structure of crystalline basement. The essential difference in tectonics between the East China Sea and the Yellow Sea mainly lies in that the velocity structures of their lower crust and upper mantle are identical to those of South China and North China respectively. In the upper mantle there exists a high-velocity zone with a nearly EW strike from the Hangzhou Bay, China, to the Tokara Channel, Japan, along about the latitude of 30°N. It is found that between the East China Sea and the Yellow Sea there are systematical differences in geomorphology, geology, seismicity, heat flow, quality factor and gravity and aeromagnetic anomalies, which is related to both left-lateral shear dislocation and right-lateral tear of the Benioff zone from the Hangzhou Bay to the Tokara Channel.It is inferred that the East China Sea was formed by Cenozoic back-arc extension. The boundary between the North China and South China crustal blocks stretches along the southern piedmont of Mts. Daba-Dabie-Hangzhou Bay-Tokara Channel, and the subduction zone at the Okinawa trench is the eastern boundary of the South China crustal block. The movements of the Pacific plate, Indian plate and upper mantle rather than the Philippine plate subduction have played a dominant role for the modern tectonic movements in East Asia. 展开更多
关键词 East China Sea and Yellow Sea 3D velocity structure surface wave tomography the Hang zhou Bay-Tokara Channel transform fault North China crustal block South China crustal block
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Inversion of Q value structure beneath the Tibet Plateau
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作者 吴建平 曾融生 《Acta Seismologica Sinica(English Edition)》 CSCD 1996年第2期271-278,共8页
A total of 11 earthquakes with 15 Rayleigh wave paths, recorded at 11 broadband digital PASSCAL seismometers installed in the Tibet Plateau by the Sino-U. S. joint research group, were used to determine the phase vel... A total of 11 earthquakes with 15 Rayleigh wave paths, recorded at 11 broadband digital PASSCAL seismometers installed in the Tibet Plateau by the Sino-U. S. joint research group, were used to determine the phase velocity and attenuation coefficient of surface waves in periods of 10-130 s. The average shear wave velocity andquality factor Qβ structures in the crust and upper mantle were obtained in this region. The result shows the average oP is low and there exists a high attenuation (Qβ= 93- 141 ) layer in the crust. The depth range of the lowoP value layer (16-42 km) is consistent with the range of low velocity layer (21-51 km) in the crust. Below63 km in the lower crust, oP decreases with depth from 114 to 34 at depth of 180 km. The low shear wave velocity and low value of Qβ at the same depth range in the crust indicate that the rocks in the range is probablymelted or Partially melted. According to the shear wave velocity structure, the average thickness of the crust is about 71 km and a clear velocity discontiniuty appears at the depth of 51 km. The low-velocity zone (4. 26 km/s) at depth of 96-180 km may be corresponding to the asthenosphere. 展开更多
关键词 Rayleigh wave phase velocity shear wave velocity structure Tibet plateau ATTENUATION Q_β structure
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A Refined Formula for the Allowable Soil Pressure Using Shear Wave Velocities
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《Journal of Civil Engineering and Architecture》 2012年第4期470-478,共9页
Based on a variety of case histories of site investigations, including extensive bore hole data, laboratory testing and geophysical prospecting at more than 550 construction sites, an empirical formulation is proposed... Based on a variety of case histories of site investigations, including extensive bore hole data, laboratory testing and geophysical prospecting at more than 550 construction sites, an empirical formulation is proposed for the rapid determination of allowable bearing pressure of shallow foundations in soils and rocks. The proposed expression corroborates consistently with the results of the classical theory and is proven to be rapid, and reliable. Plate load tests have been also carried out at three different sites, in order to further confirm the validity of the proposed method. It consists of only two soil parameters, namely, the in situ measured shear wave velocity and the unit weight. The unit weight may be also determined with sufficient accuracy, by means of other empirical expressions proposed, using P or S -- wave velocities. It is indicated that once the shear and P-wave velocities are measured in situ by an appropriate geophysical survey, the allowable bearing pressure as well as the coefficient of subgrade reaction and many other elasticity parameters may be determined rapidly and reliably. 展开更多
关键词 shear wave velocity shallow foundations allowable bearing pressure dynamic technique soils and rocks
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阿尔山火山群面波层析成像
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作者 侯颉 吴庆举 +1 位作者 余大新 叶庆东 《地震地质》 EI CSCD 北大核心 2024年第4期893-915,共23页
文中利用阿尔山火山群附近的29个宽频带流动地震台和其周边8个固定台站2019年5月—2021年12月期间的远震垂直向地震波形,通过频-时分析获取了11010条高质量的Rayleigh波基阶相速度频散,基于面波成像方法构建研究区地壳、上地幔的三维S... 文中利用阿尔山火山群附近的29个宽频带流动地震台和其周边8个固定台站2019年5月—2021年12月期间的远震垂直向地震波形,通过频-时分析获取了11010条高质量的Rayleigh波基阶相速度频散,基于面波成像方法构建研究区地壳、上地幔的三维S波速结构。结果表明:在中、下地壳范围内,阿尔山火山群地区的S波速度表现出明显的低速异常,结合该地区高波速比的特征,推测阿尔山火山群可能存在地壳岩浆囊;在阿尔山火山群地区的40~150km深度内存在多处上低下高的S波速度异常结构,表明阿尔山火山群可能发生过岩石圈拆沉;阿尔山火山群东南侧上地幔的低速异常连通了软流圈和阿尔山火山群在地表出露的位置,结合前人的研究结果推测,此低速异常可能是松辽盆地岩石圈拆沉造成的软流圈物质上涌。 展开更多
关键词 阿尔山火山群 岩石圈拆沉 火山活动 面波层析成像 S波速度结构
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Shear wave velocity structure of the crust and upper mantle in Southeastern Tibet and its geodynamic implications 被引量:25
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作者 Zhiqi ZHANG Huajian YAO Yan YANG 《Science China Earth Sciences》 SCIE EI CAS CSCD 2020年第9期1278-1293,共16页
Southeastern Tibet,which has complex topography and strong tectonic activity,is an important area for studying the subsurface deformation of the Tibetan Plateau.Through the two-station method on 10-year teleseismic Ra... Southeastern Tibet,which has complex topography and strong tectonic activity,is an important area for studying the subsurface deformation of the Tibetan Plateau.Through the two-station method on 10-year teleseismic Rayleigh wave data from 132 permanent stations in the southeastern Tibetan Plateau,which incorporates ambient noise data,we obtain the interstation phase velocity dispersion data in the period range of 5–150s.Then,we invert for the shear wave velocity of the crust and upper mantle through the direct 3-D inversion method.We find two low-velocity belts in the mid-lower crust.One belt is mainly in the SongPan-GangZi block and northwestern part of the Chuan-Dian diamond block,whereas the other belt is mainly in the Xiaojiang fault zone and its eastern part,the Yunnan-Guizhou Plateau.The low-velocity belt in the Xiaojiang fault zone is likely caused by plastic deformation or partial melting of felsic rocks due to crustal thickening.Moreover,the significant positive radial anisotropy(VSH>VSV)around the Xiaojiang fault zone further enhances the amplitude of low velocity anomaly in our VSVmodel.This crustal low-velocity zone also extends southward across the Red River fault and farther to northern Vietnam,which may be closely related to heat sources in the upper mantle.The two low-velocity belts are separated by a high-velocity zone near the Anninghe-Zemuhe fault system,which is exactly in the inner and intermediate zones of the Emeishan large igneous province(ELIP).We find an obvious high-velocity body situated in the crust of the inner zone of the ELIP,which may represent maficultramafic material that remained in the crust when the ELIP formed.In the upper mantle,there is a large-scale low-velocity anomaly in the Indochina and South China blocks south of the Red River fault.The low-velocity anomaly gradually extends northward along the Xiaojiang fault zone into the Yangtze Craton as depth increases.Through our velocity model,we think that southeastern Tibet is undergoing three different tectonic modes at the same time:(1)the upper crust is rigid,and as a result,the tectonic mode is mainly rigid block extrusion controlled by large strike-slip faults;(2)the viscoplastic materials in the middlelower crust,separated by rigid materials related to the ELIP,migrate plastically southward under the control of the regional stress field and fault systems;and(3)the upper mantle south of the Red River fault is mainly controlled by large-scale asthenospheric upwelling and may be closely related to lithospheric delamination and the eastward subduction and retreat of the Indian plate beneath Burma. 展开更多
关键词 Southeastern Tibet surface wave tomography shear wave velocity structure Xiaojiang fault system Emeishan large igneous province Asthenospheric upwelling
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基于短周期密集台阵的广州—佛山地区地壳浅部三维S波速度结构研究
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作者 高占永 叶秀薇 +4 位作者 林吉焱 段永红 王力伟 周铭 刘巧霞 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2024年第4期1454-1470,共17页
广州—佛山地区位于珠三角经济区的核心地带,三条区域性断裂从中交错穿过.广州—佛山地区精细的地壳浅部三维S波速度结构,对于研究区内的城市规划建设、地震灾害评估、强地面运动模拟等具有重要意义.本文利用布设于广州—佛山地区短周... 广州—佛山地区位于珠三角经济区的核心地带,三条区域性断裂从中交错穿过.广州—佛山地区精细的地壳浅部三维S波速度结构,对于研究区内的城市规划建设、地震灾害评估、强地面运动模拟等具有重要意义.本文利用布设于广州—佛山地区短周期密集地震台阵中的1104个台站记录到的连续波形数据,采用背景噪声互相关方法计算了台站对间的互相关函数并进一步提取到周期范围在0.1~5 s内的39488条高质量面波群速度频散曲线,然后通过基于射线追踪的面波直接反演方法计算得到了研究区内0.3~3 km深度的高分辨率三维S波速度结构.结果显示:研究区内地壳浅部S波速度横向差异显著,其中南部的珠江三角洲断陷盆地S波速度结构相对较为复杂,而北部的广花盆地内部S波速度结构则表现相对简单.研究区内的低速异常主要位于断裂附近,且大都位于断裂的下降盘.珠江三角洲内三水盆地东缘表现为马鞍状低速异常,向下最大延伸至2 km,低速体南北两侧边界与控盆断裂位置基本一致.广花盆地内部存在两个平行排列的高速异常,中间夹持一平行构造走向的低速异常,总体速度结构特征符合广花盆地为一复式向斜的地质构造背景.低速异常向下延伸至1.4 km深度处,可能指示了卷入向斜地层的最大埋深.沿广州—从化断裂发育条带状低速异常,与沿断裂形成的沉积地层有关.条带状异常在浅部分为两段,表明广州—从化断裂在历史上可能具有分段活动性.玉带公园周围被高速异常环绕,异常向上延伸至距地表约1.3 km处,结合研究区已有资料推测该高速异常可能为早期岩浆侵入在地壳浅部的反映. 展开更多
关键词 密集台阵 背景噪声成像 地壳浅部 S波速度结构 广州—佛山
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非基岩场地基础隔震核岛厂房抗震性能分析
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作者 刘宇 李建波 +1 位作者 丁志新 林皋 《哈尔滨工程大学学报》 EI CAS CSCD 北大核心 2024年第9期1679-1686,共8页
为了研究非基岩场地条件下基础隔震核电工程结构的抗震性能,本文依据外源波动理论提出了考虑土-结构相互作用效应的基础隔震核电工程结构抗震分析方法,该方法实现了地震动的高精度输入以及整体系统的直接求解,通过与传统封闭体系振动法... 为了研究非基岩场地条件下基础隔震核电工程结构的抗震性能,本文依据外源波动理论提出了考虑土-结构相互作用效应的基础隔震核电工程结构抗震分析方法,该方法实现了地震动的高精度输入以及整体系统的直接求解,通过与传统封闭体系振动法计算结果的对比验证了其有效性。建立了基础隔震核岛厂房-地基整体有限元模型,开展了核岛厂房地震响应分析,讨论了不同剪切波速场地条件下核岛厂房的基础隔震性能。研究结果表明:非基岩场地条件下基础隔震核岛厂房表现出良好的隔震效果;随着场地剪切波速的降低,基础隔震的隔震能力逐渐下降,与剪切波速为1067 m/s的场地相比,当场地的剪切波速为305 m/s时,核岛厂房结构顶部的楼层反应谱、加速度放大系数和层间位移角的隔震率分别减小了14.30%、13.50%和23.41%。为了保证核电工程结构的安全性,在基础隔震设计中应充分考虑非基岩场地条件下的SSI效应。 展开更多
关键词 基础隔震 核岛厂房 非基岩场地 土-结构相互作用 外源波动 振动法 剪切波速 地震响应
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