The broad-band fractal nature of heterogeneity in the upper crust from petrophysical logs   总被引：2，自引：0，他引：2  

Sean Dolan  Christopher Bean  & Bruno Riollet 《Geophysical Journal International》1998,132(3):489-507

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Geological and geophysical evidence for large palaeo-earthquakes with surface faulting in the Roer Graben (northwest Europe)   总被引：2，自引：0，他引：2  

Thierry Camelbeeck  & Mustapha Meghraoui 《Geophysical Journal International》1998,132(2):347-362

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The crustal structure of Central East Greenland:results from combined land–sea seismic refraction experiments     

Holger A.F. Mandler  & Wilfried Jokat 《Geophysical Journal International》1998,135(1):63-76

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Crustal structure above the Iceland mantle plume imaged by the ICEMELT refraction profile   总被引：2，自引：0，他引：2  

Fiona A. Darbyshire  Ingi Th. Bjarnason  Robert S. White  & Ólafur G. Flóvenz 《Geophysical Journal International》1998,135(3):1131-1149

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Variability of geophysical log data and the signature of crustal heterogeneities at the KTB   总被引：2，自引：0，他引：2  

Sabrina Leonardi  & Hans-Joachim Kümpel 《Geophysical Journal International》1998,135(3):964-974

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西安地区区域地壳稳定性评价   总被引：2，自引：0，他引：2  

熊润清  杨家骑  谢振乾  杨建军  郑宁平 《陕西地质》1992,(1)

本文依据“七五”期间对西安地区进行区域地壳稳定性与地质灾害评价和研究工作所取得的地质、物探、测量、模拟实验等方面的成果资料,考虑到内、外动力地质作用及介质条件,运用模糊数学方法进行了稳定性评价与区划,将西安地区地壳稳定性划分为较稳定、次较稳定、次较不稳定、较不稳定、不稳定五级。在此基础上,对西安地区主要城市的建设与发展规划提出了指导性的建议。  相似文献   

3-D Crustal Velocity Structure in Northwestern Greece     

G.?DrakatosEmail author  N.?Voulgaris  M.?Pirli  N.?Melis  B.?Karakostas 《Pure and Applied Geophysics》2005,162(1):37-51

— The three-dimensional crustal velocity structure in the area of the northwestern Greek mainland was determined by P-wave travel time inversion, applying a two-step tomography procedure. The data set consists of the travel-time residuals of 584 well located earthquakes. In order to improve the initial (reference) velocity model, before the inversion of travel times, the minimum 1-D model was determined. Several tests were conducted to estimate model stability and hypocenter uncertainties. The velocity distribution in the shallow layers (4 and 7 km) is strongly affected by the crustal thickness variation and the complex tectonics. A first, well-defined velocity discontinuity appears at a depth of 3–6 km, along the Hellenides Mountain chain. A second low velocity anomaly is detected at a depth of 9–12 km and may be connected with the Alpidic orogenesis. Another interesting feature appears beneath the Amvrakikos Gulf (horstgraben structure), where relatively low velocities (<6.0 km^-1) appear to a depth of 20 km. Finally, a well-pronounced velocity boundary is found at a depth of 16 km. In general, low velocities are predominant along the Dinarides-Hellenides Mountain chain, rather typical for the upper crust.Acknowledgement. The authors thank the referees for their useful comments. Moreover, we would like to thank the General Secretariat for Research and Technology of Greece, for the partial support of this study.  相似文献   

The seismic velocity structure north of Iceland from joint inversion of local earthquake data     

C.?RiedelEmail author  A.?Tryggvason  T.?Dahm  R.?Stefanson  R.?B?dvarson  G.?B.?Gudmundsson 《Journal of Seismology》2005,9(4):383-404

The tectonics of North Iceland is dominated by interaction of the Iceland hot spot and the mid-oceanic Kolbeinsey Ridge. Transform movement along the transition zone, often called Tjörnes Fracture Zone, and the seismicity it generates has been documented in the past. This study uses the seismicity data of the permanent South Iceland Lowland (SIL) network to quantify velocity structure from travel time inversion. The SIL seismic dataset is capable of illuminating parts of the region in a 3D seismic velocity inversion, primarily between 7 and 12 km depth, with less resolution elsewhere because of the sparse setup of the monitoring network. The problem has been analysed in 1, 2 and 3 dimensions and evaluated with 4 different inversion tools. The study reports a correlation of a seismic velocity anomaly in compressional wave velocity v _p and shear wave velocity v _s with the Husavik-Flatey fault and a further subsurface lineament stretching between the islands of Flatey and Grimsey. Finally, our results support a decrease of crustal thickness between the mainland and the island of Grimsey.  相似文献   

Travel-times and Attenuation Relations for Regional Phases in the Barents Sea Region     

E. C.?HicksEmail author  T.?Kv?rna  S.?Mykkeltveit  J.?Schweitzer  F.?Ringdal 《Pure and Applied Geophysics》2004,161(1):1-19

A database containing 45 events in the Barents Sea region has been compiled and analyzed with the aim of evaluating crustal models, travel-times and attenuation relations in the context of performing regional detection threshold monitoring of this region. The 45 events are mostly located around the circumference of the study area due to the virtually aseismic nature of the Barents Sea itself. Regional P _n and S _n phases were observable for most events in the database, while P _g and L _g phases were only observable for events with raypaths that do not cross the tectonic structures in the Barents Sea. This corroborates a number of previous observations of L _g -wave blockage within the Barents Sea. Three existing velocity models were evaluated, with a model having slightly lower S velocities than earlier assumed in the upper mantle giving the overall best fit to the observed arrivals. In order to estimate magnitudes, short-term average (STA) and spectral amplitude values were calculated in several frequency bands for all phase arrivals in the database. There were no significant differences between spectral and STA amplitudes, so the latter were used as this parameter is more efficient to calculate in real-time processing. An inversion was performed in order to determine an attenuation relation specific for this region. The resulting magnitudes based on P _n , P _g , S _n and L _g phases gave an internally consistent, reasonably stable set of values, which can be calibrated towards any existing global or regional scale.  相似文献   

南海北部大陆坡-深海盆过渡区的地壳性质     

刘建华 《热带海洋学报》1993,(2)

地质、地球物理资料综合分析表明,南海北部大陆坡-深海盆过渡区(114°—118°E,17°—20°N)内的深海盆属洋壳,其前新生代基底由大洋玄武岩组成,地壳厚度有自东向西增厚的趋势;区内的大陆坡属拉张减薄的过渡壳,其前新生代基底由古生代和中生代变质岩、沉积岩和岩浆岩组成。大陆坡西部有较多中、基性岩浆活动,故局部高磁异常较东部发育。  相似文献