Relationship between the seismicity and geologic structure of the Blanco Transform Fault Zone     

Robert P. Dziak  Christopher G. Fox  Robert W. Embley 《Marine Geophysical Researches》1991,13(3):203-208

Morphologic studies of an oceanic transform, the Blanco Transform Fault Zone (BTFZ), have shown it to consist of a series of extensional basins that offset the major strike-slip faults. The largest of the extensional basins, the Cascadia Depression, effectively divides the transform into a northwest segment, composed of several relatively short strike-slip faults, and a southeast segment dominated by fewer, longer faults. The regional seismicity distribution (m _b 4.0) and frequency-magnitude relationships (b-values) of the BTFZ show that the largest magnitude events are located on the southeast segment. Furthermore, estimates of the cumulative seismic moment release and seismic moment release rate along the southeast segment are significantly greater than that of the northwest segment. These observations suggest that slip along the southeast segment is accommodated by a greater number of large magnitude earthquakes. Comparison of the seismic moment rate, derived from empirical estimates, with the seismic moment rate determined from plate motion constraints suggests a difference in the seismic coupling strength between the segments. This difference in coupling may partially explain the disparity in earthquake size distribution. However, the results appear to confirm the relation between earthquake size and fault length, observed along continental strike-slip faults, for this oceanic transform.  相似文献   

陕西勉略宁地区金、多金属矿产控矿条件及成矿模式   总被引：1，自引：0，他引：1  

《陕西地质》1997,(2)

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9608号台风登陆北上总能量变化及渤海高压维持   总被引：10，自引：1，他引：9  

晁淑懿  仇永炎  汪迎辉 《气象》1998,24(6):3-10

首先分析了属于台风与西风槽的相互作用型的９６０８号台风在其登陆泊台风核心区总能量及其组成部分的变化。结果指出,决定总能量再度增长的主要是潜热能,而此时潜热能的增长是同台风东侧低层偏南急流有密度关系。台风的东北象限内潜热能增长最盛,特大暴雨区恰也在这个象限。其次利用对流层高层散度风场与旋转风场的配置,从散度风动勇与旋转风动能之间的转换关系,半定量地估计台风东侧黄海、渤海、日本海高压上空反气旋环流的增  相似文献   

多角辐散地极技术在高电阻率地区的应用     

廖必军 《气象科技》2007,35(4):567-570

在高电阻率地区,建造符合要求且经济实用的地网一直是防雷工程施工的难点。因为组成地网的接地极的形状关系到材料利用效率和施工难易程度。提出了"多角辐散地极"的概念,设计制作了多角辐散地极,并选择了3个不同的地域环境,对这一设计技术进行了试验。通过与普通地网的比较,证明了在高阻率地区多角辐散地极组成的地网优于普通地网。通过对不同安装距离,不同降阻剂投放量的比较,确定了多角辐散地极的最佳安装方法,并根据试验测量的数据计算出并联系数,得出工程量的估算方法。  相似文献   

GPS中CCD技术的原理与应用   总被引：2，自引：2，他引：0  

谢世杰  高启贵 《测绘工程》1999,8(4):12-17

码／载波相位扩散技术可使单频ＧＰＳ接收机的测程从２０ｋｍ急剧扩大到４００ｋｍ。本文叙述其简单原理与实际应用。  相似文献   

渤海海域的郯庐扭断裂及含油气盆地的发育   总被引：8，自引：1，他引：8  

严俊君  马前贵 《地球科学》1992,17(1):31-38

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Phylogeography of Ophryotrocha labronica (Polychaeta,Dorvilleidae) along the Italian coasts          下载免费PDF全文

Piero Cossu  Ferruccio Maltagliati  Federica G. Pannacciulli  Roberto Simonini  Gloria Massamba‐N'Siala  Marco Casu  Claudio Lardicci  Daniela Prevedelli  Alberto Castelli 《Marine Ecology》2015,36(4):1088-1097

Species of the genus Ophryotrocha are a well‐studied group of organisms but, despite the relatively large body of biological studies, little is known about their intra‐specific patterns of genetic diversity. In the present study, we analysed the patterns of genetic variation in samples of Ophryotrocha labronica (Polychaeta, Dorvilleidae) collected along the Italian coasts within three regions with different thermal regimes: the Northern Adriatic Sea (NAS), the Ligurian Sea (LS), and the South/Southeast Sicilian Sea (SS). A partial sequence of the cytochrome c oxidase subunit I (COI) gene was used as a genetic marker. An analysis of molecular variance (AMOVA) showed significant genetic differentiation between the NAS and the other regions. Conversely, little or no genetic structuring was found between the LS and the SS or amongst locations within a given region. A Bayesian phylogenetic tree and a median‐joining network provided evidence for the occurrence of two highly divergent genetic lineages characterized by a high average sequence divergence (17.2%, Kimura two‐parameter distance). The spatial patterns of genetic variation found in O. labronica may reflect the signature of past expansion events of the two genetic lineages. Although the high sequence divergence suggested that cryptic speciation within O. labronica may have occurred, other traits such as the absence of reproductive isolation, pattern of phenotypic variation and habitat specificity prompted us to regard the two groups as distinct COI lineages of O. labronica.  相似文献   

近地质时期岩石圈板块构造运动的力学分析     

程学友 《地质与勘探》1995,31(5):15-22

运用相对运动的地球动力学理论，把软流圈以上的岩石圈和软流圈以下的地球内圈，作为两个独立的运动单元来考察它们随地球自转时所发生的变化和各自的运动状态。完整的岩石圈碎裂成岩石块之后，它们各自作为独立的单元，在纬向西漂力、经向离极力和洋底扩张力联合作用下，产生相对运动。  相似文献   

Vector magnetic analysis within the southern Ayu Trough, equatorial western Pacific   总被引：2，自引：1，他引：2  

Sang-Mook Lee  Seung-Sep Kim 《Geophysical Journal International》2004,156(2):213-221

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Divergent evolution in fluviokarst landscapes of central Kentucky     

Jonathan D. Phillips  Linda L. Martin  Viva G. Nordberg  William A. Andrews 《地球表面变化过程与地形》2004,29(7):799-819

Central Kentucky is characterized by a mixture of karst and ?uvial features, typically manifested as mosaic of karst‐rich/channel‐poor (KRCP) and channel‐rich/karst‐poor (CRKP) environments. At the regional scale the location and distribution of KRCP and CRKP areas are not always systematically related to structural, lithological, topographic, or other controls. This study examines the relationship of KRCP and CRKP zones along the Kentucky River gorge area, where rapid incision in the last 1·5 million years has lowered local base levels and modi?ed slopes on the edge of the inner bluegrass plateau. At the scale of detailed ?eld mapping on foot within a 4 km² area, the development of karst and ?uvial features is controlled by highly localized structural and topographic constraints, and can be related to slope changes associated with retreat of the Kentucky River gorge escarpment. A conceptual model of karst/?uvial transitions is presented, which suggests that minor, localized variations are suf?cient to trigger a karst–?uvial or ?uvial–karst switch when critical slope thresholds are crossed. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献