利用体波层析成像技术研究欧亚及邻区地幔三维速度结构          下载免费PDF全文

程先琼  朱介寿  蔡学林 《沉积与特提斯地质》2003,23(2):90-94

根据体波层析成像技术,利用大量走时数据,做出0°～180°E,30°S～90°S范围内0～2889km深的三维速度分布图像,得到欧亚地区局部区域岩石圈及地幔的高分辨率速度结构,并从地球动力学角度出发对这些成像结果做进一步解释。  相似文献   

地震CT勘探原理及其在公路隧道病害诊断中的应用   总被引：9，自引：2，他引：9  

孙宇  肖宽怀  赵永贵 《工程地质学报》2003,11(4):440-444

地震CT勘探是一种新的地球物理方法。具有分辨率高、可靠性强、信息量大、图象直观的特点。可以广泛地用于线路、场地、隧道、边坡等项目的工程地质勘查和病害诊断。在元磨高速公路芭蕉箐隧道的地质病害诊断中应用地震CT进行勘探,取得了良好的效果。  相似文献   

Seismic evidence for deep low-velocity anomalies in the transition zone beneath West Antarctica   总被引：1，自引：0，他引：1  

Anne Sieminski  Eric Debayle  Jean-Jacques Lévêque 《Earth and Planetary Science Letters》2003,216(4):645-661

We present a three-dimensional (3D) SV-wave velocity model of the upper mantle beneath the Antarctic plate constrained by fundamental and higher mode Rayleigh waves recorded at regional distances. The good agreement between our results and previous surface wave studies in the uppermost 200 km of the mantle confirms that despite strong differences in data processing, modern surface wave tomographic techniques allow to produce consistent velocity models, even at regional scale. At greater depths the higher mode information present in our data set allows us to improve the resolution compared to previous regional surface wave studies in Antarctica that were all restricted to the analysis of the fundamental mode. This paper is therefore mostly devoted to the discussion of the deeper part of the model. Our seismic model displays broad domains of anomalously low seismic velocities in the asthenosphere. Moreover, we show that some of these broad, low-velocity regions can be more deeply rooted. The most remarkable new features of our model are vertical low-velocity structures extending from the asthenosphere down to the transition zone beneath the volcanic region of Marie Byrd Land, West Antarctica and a portion of the Pacific-Antarctic Ridge close to the Balleny Islands hotspot. A deep low-velocity anomaly may also exist beneath the Ross Sea hotspot. These vertical structures cannot be explained by vertical smearing of shallow seismic anomalies and synthetic tests show that they are compatible with a structure narrower than 200 km which would have been horizontally smoothed by the tomographic inversion. These deep low-velocity anomalies may favor the existence of several distinct mantle plumes, instead of a large single one, as the origin of volcanism in and around West Antarctica. These hypothetical deep plumes could feed large regions of low seismic velocities in the asthenosphere.  相似文献   

Seismic risk assessments and GIS technology: applications to infrastructures in the Friuli–Venezia Giulia region (NE Italy)     

Raffaella Codermatz  Rinaldo Nicolich  Dario Slejko 《地震工程与结构动力学》2003,32(11):1677-1690

This paper illustrates the seismic risk preliminary estimates of two different groups of structures located on the territory of the Friuli–Venezia Giulia region (NE Italy) : the first group includes some special industrial plants, and the second group includes bridges and tunnels belonging to the regional highway network. The part of the study on special industrial plants tries to evaluate the degree of expected damage, taking into account their structural typology and ground shaking expressed in terms of macroseismic intensity. The second part of the study is an application of the HAZUS methodology to the tunnels and bridges of a highway network: the combination of expected ground shaking and the construction characteristics lead to very different risk levels, especially when considering the bridges. The resulting damage levels to bridges and tunnels are still only indicative because of the fragility curves used in the evaluations: they were developed for existing bridge and tunnel structural typologies in the U.S.A. Moreover, both examples show the power of GIS technology in storing, elaborating, and mapping spatial data. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Velocity structure of uppermost mantle beneath North China from Pn tomography and its implications   总被引：1，自引：0，他引：1  

汪素云  许忠淮  裴顺平 《中国科学D辑(英文版)》2003,46(Z2)

20301 Pn arrival time data are collected from the seismological bulletins of both national and regional seismic networks. Pn travel time residuals are tomographically inverted for the Pn velocity structure of uppermost mantle beneath North China. The result indicates that the average Pn velocity in North China is 7.92 km/s, and the velocity varies laterally from ?0.21 to +0.29 km/s around the average. The approximately NNE trending high and low velocity regions arrange alternatively west-eastward. From west to east we can see high velocity in the middle Ordos region, the Shanxi graben low, the Jizhong depression high, the west Shandong uplift and Bohai Sea low, and the high velocity region to the east of the Tanlu fault. In the southern boundary zone of the North China block, except for the high velocity in the Qingling Mountains region, the velocity is generally lower than the average. Obvious velocity anisotropy is seen in the Datong Cenozoic volcanic region, with the fast velocity direction in NNE-SSW. Notable velocity anisotropy is also seen around the Bay of Bohai Sea, and the fast velocity directions seem to show a rotation pattern, possibly indicating a flow-like deformation in the uppermost mantle there. The Pn velocity variations show a reversed correlation with the Earth's heat flow. The low Pn velocity regions generally show high heat flow, e.g., the Shanxi graben and Bohai Sea region. While the high Pn velocity regions usually manifest low heat flow, e.g., the region of Jizhong depression. This indicates that the Pn velocity variation in the study region is mainly aroused by the regional temperature difference in the uppermost mantle. Strong earthquakes in the crust tend to occur in the region with the abnormal low Pn velocity, or in the transition zone between high and low Pn velocity regions. The earthquakes in the low velocity region are shallower, while that in the transition zone are deeper.  相似文献   

新产业区的形成机制及其与传统空间组织理论的关系   总被引：8，自引：1，他引：8  

田明  樊杰 《地理科学进展》2003,22(2):186-194

在新产业区概念和特征进行概括的基础上,归纳了产业区发展的一般过程,并重点对新产业区的形成机制及所具有的优势进行了探讨。地方化产业群及区域创新网络的形成是新产业区成熟的标志,知识外溢、经济外部性导致的收益递增,以及基于密切的内部联系引来交易成本的降低使新产业区获得了强大的经济竞争优势,新产业区的空间组织形式所具有的网络效应、创新效应和企业与地方文化的良好融合是经济竞争优势的根本。最后,对新产业区理论和传统的空间组织理论之间的关系进行了对比分析,总结了二者的之间的异同。  相似文献   

Architecture of fault zones determined from outcrop, cores, 3-D seismic tomography and geostatistical modeling: example from the Albalá Granitic Pluton, SW Iberian Variscan Massif     

J. Escuder Viruete  R. Carbonell  D. Martí  M. J. Jurado  A. Prez-Estaún 《Tectonophysics》2003,361(1-2):97-120

The 3-D seismic tomographic data are used together with field, core and well log structural information to determine the detailed 3-D architecture of fault zones in a granitic massif of volume 500×575×168 m at Mina Ratones area in the Albalá Granitic Pluton. To facilitate the integration of the different data, geostatistical simulation algorithms are applied to interpolate the relatively sparse structural (hard) control data conditioned to abundant but indirect 3-D (soft) seismic tomographic data. To effectively integrate geologic and tomographic data, 3-D migration of the velocity model from the time domain into the depth domain was essential. The resulting 3-D model constitutes an image of the fault zone architecture within the granitic massif that honours hard and soft data and provides an evaluation of the spatial variability of structural heterogeneities based on the computation of 3-D experimental variograms of Fracture Index (fault intensity) data. This probabilistic quantitative 3-D model of spatially heterogeneous fault zones is suitable for subsequent fluid flow simulations. The modeled image of the 3-D fault distribution is consistent with the fault architecture in the Mina Ratones area, which basically consists of two families of subvertical structures with NNE–SSW and ENE–WSW trends that displaces the surfaces of low-angle faults (North Fault) and follows their seismically detected staircase geometry. These brittle structures cut two subvertical dykes (27 and 27′ Dykes) with a NNE–SSW to N–S trend. The faults present high FI (FI>12) adjacent bands of irregular geometry in detail that intersect in space delimiting rhombohedral blocks of relatively less fractured granite (FI<6). Both structural domains likely correspond with the protolith and the damaged zone/fault core in the widely accepted model for fault zone architecture. Therefore, the construction of 3-D grids of the FI in granitic areas affected by brittle tectonics permits the quantitative structural characterization of the rock massif.  相似文献   

CT长骨测量在骨折髓内钉固定术中的应用     

王越  徐均超  高艳 《CT理论与应用研究》2003,12(2):33-35

目的：探讨CT在长骨测量中的应用价值.方法：经X线检查证实的肱骨、股骨、胫骨骨折患者600多例，其中302例临床行髓内钉固定术，并在术前进行了健侧骨的CT定位扫描，测量其两点之间骨干长度及骨髓腔最窄处的宽度。结果 依据术前CT定位测量数据而选择的髓内钉在手术中完全适用。结论：此方法操作简便测量数据准确为临床提供可靠依据。  相似文献   

多相流动电磁波成像测井测量敏感场计算   总被引：8，自引：1，他引：8       下载免费PDF全文

赵亮  吴锡令 《地球物理学报》2003,46(6):870-874

在多相流动电磁波成像测井研究中，测量敏感场是设计测量仪器和研究图像重建算法的前提工作. 本文用数值方法计算多相流动电磁波成像测井测量敏感场. 根据测量探头电极阵列的对称性，将三维敏感场问题划分为轴向和横向两个平面问题，然后应用有限元算法求解两个平面电势分布问题，对于不同介质模型，计算各种测量条件下测量区域内电势分布，进而根据电势分布计算测量敏感场. 结果表明测量敏感区域为发射电极到测量电极的弧形区域，在发射电极到测量电极的电势梯度线上，测量敏感函数近似于一个指数函数.  相似文献   

上地幔顶部折射波走时层析成像研究综述   总被引：2，自引：0，他引：2  

裴顺平  许忠淮  汪素云 《地球物理学进展》2003,18(1):59-64

简要介绍了上地幔顶部折射波走时层析成像研究的发展历程，详细介绍了上地幔项部折射波走时层析成像研究的各种方法并分析了其优缺点，介绍了国内外有关上地幔顶部折射波的研究工作和成果，阐述了上地幔顶部速度结构与构造活动的关系及其地球动力学意义。  相似文献