The natural basis of the formation of the dual-nuclei structural model     

LU Yuqi  Yehua Dennis Wei 《地理学报》2003,13(1):85-96

The dual-nuclei spatial structure is composed of a regional central city, a port city and their spatial relations in certain regions. In general, this spatial structure could be found in most of the coastal regions or regions along big rivers. In terms of the mechanism, the dual-nuclei structure is the result of the spatial interaction and the complementary characteristics of the center city and the port city. The "marginal function" of the port city and its relationship with the central city has long been discussed in the literature. On the one hand, drainage area is the main natural geographical background of the formation of the dual-nuclei spatial structure; therefore, we can build a theoretical geographic structure that is based on the drainage area. On the other hand, vicissitude of the coastline also has important influence on the formation of the dual-nuclei spatial structure. It is especially meaningful if we can notice this when we examine deeply the research on the spatial structure of delta.  相似文献   

Coastline configuration and geomorphologic development mode of arc-shaped coast in South China     

DAI Zhijun  LI Chunchu 《地理学报》2004,14(4):473-480

Coastline configuration indexes of 34 typical arc-shaped coasts in South China are investigated by the method of principal component analysis, and meanwhile deposition and geomorphologic features of arc-shaped coast are also analyzed. The results show: (1) The configuration of arc-shaped coast in South China is of the characteristic of variability and complexity. (2) The wave power and the openings of the bay are the decisive factors to result in the changes of the configuration of the arc-shaped coast in South China, however, incidence direction of the wave has no effect on configuration development of the coast. (3) Commonly, geomorphologic modes of the arc-shaped coast system in South China consist of barriers, lagoons and tidal-inlets, and can be divided into four types: the openings of the bay leaning to the east, the openings of the bay leaning to the south, the openings of the bay leaning to the west and the openings of the bay leaning to the north.  相似文献   

THE CONCEPT,REVIEW AND NEW INSIGHTS OF THE ACTIVE-TECTONIC BLOCK HYPOTHESIS          下载免费PDF全文

ZHENG Wen-jun  WANG Qing-liang  YUAN Dao-yang  ZHANG Dong-li  ZHANG Zhu-qi  ZHANG Yi-peng 《地震地质》1979,42(2):245-270

The hypothesis that strong earthquakes in China mainland are controlled by the movement and interaction of active-tectonic blocks was advanced by Chinese scientists, with the remarkable ability to encompass geological and geophysical observations. Application of the active-tectonic block concept can illustrate 6 active-tectonic block regions and 22 active-tectonic blocks in mainland China and its neighboring regions. Systems of active-tectonic block boundaries are characterized by a zone of decades or hundreds of strong earthquakes. One of the greatest strengths of the modern active-tectonic block hypothesis is its ability to explain the origin of virtually all the M8 and 80% M7 earthquakes on the main continent in eastern Asia. In other words, active-tectonic block boundary stands in strong causal interrelation with recurrence behaviors of strong earthquakes and thus, it is possible to predict an earthquake occurrence in principle. After nearly two decades of development and improvement, the active-tectonic block hypothesis has established its theoretical foundation for the active tectonics and earthquake prediction, and is promoting the transition from probabilistic prediction to physical prediction of strong earthquakes. The active-tectonic block concept was tested by application to a well-documented, high-frequent earthquake area, and was found to be an effective way of describing and interpreting the focal mechanism and seismogenic environment, but there are still many problems existing in the active-tectonic block hypothesis, which confronts with rigorous challenges. Future progress will continue to be heavily dependent on the high-precision synthetic seismogram, especially of critical poorly documented settings. It is well known that strong earthquakes occur anywhere in the interactions among the active-tectonic block boundaries where there is sufficient stored elastic strain energy driving fault propagation, and then releasing the stored energy. Therefore, future studies will focus on the mechanism and forecast of the strong earthquake activity in the active-tectonic block boundary zone, with fault activity within the active-tectonic block boundary zone, quantifying current crustal strain status, upper crust and deep lithosphere coupling relation, strong earthquake-generating process and its precursory variation mechanism in seismic geophysical model as the main research contents, which are the key issues regarding deepening the theory of active-tectonic block and developing continental tectonics and dynamics in the modern earth science.  相似文献   

我国大陆高精度、高分辨率大地水准面的研究和实施   总被引：36，自引：5，他引：36  

陈俊勇  李健成  宁津生  张骥  张燕平 《测绘学报》2001,30(2):95-100

首先结合高分辨率的 DTM和现有重力资料推算我国局域重力大地水准面 ;然后再和我国 GPS水准所构成的高程异常控制网拟合 ,推算了具有分米级精度 ,1 5′× 1 5′分辨率的我国大陆大地水准面。  相似文献   

中国大陆及其邻域地壳上地幔速度结构的面波层析成像研究.   总被引：13，自引：5，他引：13       下载免费PDF全文

何正勤  丁志峰  叶太兰  孙为国  张乃铃 《地震学报》2001,24(6):596-603

利用中国数字化地震台网（CDSN）11个台站和IRIS在中国周边的12个数字地震台站的长周期瑞利面波资料，根据面波群速度层析成像方法反演得到的10～92ｓ周期范围内的25个中心周期的群速度分布资料，用光滑约束的遗传算法反演得到了中国大陆及其邻域的地壳上地幔横波三维速度结构；给出了沿北纬30、38两条东西向剖面和沿东径90、120两条南北向剖面的地壳上地幔横波速度结构，并在４个不同深度的水平切片上展示了中国大陆及邻域的横波速度分布图象．   相似文献   

东南亚和中国大陆7级地震活动的关系     

苏鸾声 《地震研究》2001,24(3):219-224

根据图形对比、频度比及相关分析法，对1900年以来东南亚和中国大陆地震活动的关系进行了研究，结果表明，东南亚地区和中国大陆7级地震活动是相关的。东南亚地区7级地震活动对中国大陆地震活动的影响可迟后1，2年；根据2000年全球7级大震在东南亚地区出现相对集中的情况，可以预测中国大陆在2001或2002年发生7级以上地震的可能性很大。  相似文献   

中国大陆主震后十年内的强余震活动分析     

胡先明 《四川地震》1993,(2):29-36

晚期强余震往往会使曾经历过主震破坏后重建的地区再次遭受预想不到的损失。本文在较系统地整理资料的基础上,初步获得中国大陆主震后10年内强余震活动的部分统计特征,并初步尝试利用主震后1个月的资料,运用推广的贝叶斯公式对主震后2月—10年期间是否会发生强余震进行判别。同时,分析了强余震与主震空间位置的关系。结果表明:①主震后10年内有强余震的占总数1/3,主余震型地震超过总数1/4,强余震频次随时间衰减很快。②以主震后1月内的强余震资料用推广的贝叶斯公式,可以判别出2月—10年期间是否会发生强余震。③上述方法的Wallcn评分结果比较好。  相似文献   

DEPOSITIONAL CHARACTER AND SHORELINE CHANGES OF THE NANDUJIANG DELTA,HAINAN ISLAND,CHINA     

Wang Baocan  Zhang Keqi 《地理学报(英文版)》1994,(Z2)

.Introducti0nTheNandujianghiver,withalengthOf3llkIn,adrainageareaof684lkm2andanaverageannunldischargOf60xl09m',isthelargstriveronHainanIsland.IttransportsanaveragannualsedimentloadOfO.68xlO6tonsnorthwdintoQangrhouStrait,wherethetidalrangnisca1.Om,andwavesandlongrhorecurrentsarerelativelystrong.TheNandujiangdeltacoves20OkIn2.ThedePOsitionalSystemOfthedeltaconsistsofrivermouthbars,distribotarymouthbars,marshdepositsfOrmedinbaysandlagoons,sandridges,sandsPitsanddunes.ThedistributionPatt…  相似文献   

中国大陆的特征地震活动及其中一长期预测研究（一）     

闻学泽  罗灼礼  陈农  胡先明 《中国地震》1994,(2)

中国大陆不同地点２４个特征地震轮回的震级一时间序列分析表明：在一个完整轮回中，相继特征地震事件ｉ和ｊ之间时段的前１／２极少有破坏性地震发生；而在轮回的后１／２，大多数情况下至少有一次中－强地震发生；其中，中一强地震发生在轮回最后１／３时段的约占５４％。称这种地震为“填隙式中强震”（事件ｆ），其发生可能标志着当地自从上一次特征地震后，应变已重新积累到达距下一次特征地震极限应变不远的背景，故对于发生在轮回末尾的特征事件ｊ来说，具有作为中一长期“前兆”的意义。有可能识别出的首次填隙式中强震（事件ｆ１），其强度通常比同一轮回开始的特征事件ｉ小１—２个震级单位，但明显大于当地背景地震活动强度，并发生在与事件ｉ和ｊ相同的空间位置。文中初步建立起中国大陆完整特征地震活动轮回的震级－时间序列模式（ｉ－ｆ－ｊ模式），它将作为本研究第二部分中进一步发展特征地震中－长期预测方法的基础。  相似文献   

TEMPORAL ORDERLINESS OF EARTHQUAKES (M≥8) ON CHINA MAINLAND——A NEW APPROACH TO THE PREDICTION OF EARTHQUAKES   总被引：2，自引：0，他引：2  

Xu Dao-yi  Huang Jian-fa  Wang Xiang-nan 《地震地质》1991,13(3):237

Some great earthquakes of magnitude 8 or greater on China mainland repeatedly occurred at the intervals of 252, 94, 48, and 25 years. It incited us to study the time interval between every pair of great earthquakes (M≥8) on China mainland. The result shows that there are four groups of clear orderliness distinguished in the most disorder distribution of earthquakes. The distinguished orderliness can be used to estimate the occurrence of next great earthquakes in China  相似文献