Long-term seismic noise investigations on Shikotan Island: First results     

Yu. A. Kugaenko  V. A. Saltykov  V. I. Sinitsyn  A. A. Shishkin 《Russian Journal of Pacific Geology》2008,2(3):218-227

In 2003–2004, long-term seismic noise observations were launched on Shikotan Island (Lesser Kuril Range) based on the “Shikotan” dormant regional seismic station. The geological and geophysical data on the registration area are reported. Information about the equipment and its technical specifications is given. The precursors to the strongest local earthquakesthat occurred in the Shikotan Island region in January 2005–March 2007 are identified.  相似文献   

Micro-fracture instabilities in granular solids     

Gabriela Bilbie  Cristian Dascalu  Rene Chambon  Denis Caillerie 《Acta Geotechnica》2008,3(1):25-35

We study the aspect of unstable behavior (like strain localization bands) in elastic solids as a consequence of micro-fracturing. A two-scale approach of computational homogenization is considered. The macroscopic behavior is investigated by finite element computations on a unit cell. At the micro-level, we consider a granular structure with elastic grains. The inter-granular boundaries are modeled with cohesive laws, friction and unilateral contact. We show that decohesion between grains gives rise to macro-instabilities, indicated by the loss of ellipticity, typical for deformation localization bands. The relation between the microscopic softening on inter-granular boundaries and the onset of macro-instabilities is studied through numerical examples. The influence of the cohesive law and friction parameters is analyzed. For periodic distributions of granular structures, we prove the loss of periodicity by failure and the corresponding size dependence effect in the homogenized response. We present numerical examples of bifurcation of solutions for granular cell structures and of particular solutions specific to elementary volumes with periodic cell distribution. Size dependence appears in the unstable regime and is strongly influenced by cohesion and friction parameters.  相似文献   

震灾保险研究中的软科学问题     

巫孟还  徐蓓蕾 《国际地震动态》1996,(3):18-21

震灾保险研究融会着自然科学与社会科学的紧密结合和相互渗透,基于这一认识,本文联系震灾保险的社会属性,分析并指出这一险种的非强制性质;保护应用的权益与责任;对社会不规范投保行为的制约;正确理解“与国际惯例接轨”、地震系统的协作模式、政府部门的政策导向等等带有根本性的问题,以启示人们把握研究的大方向,从而加快我国该项研究的实用化进程。  相似文献   

研究“源兆”的若干问题及途径分析   总被引：3，自引：3，他引：0  

王贵宣  张肇诚 《地震》1996,16(4):391-395

从位场理论的观点讨论了场和源的概念,建议将“场兆”改称为构造前兆,将“源兆”称为震源前兆。文中还分析了震源体与各种前兆观测方法探测的深度,并根据地磁与重力观测方法不同的物理基础和地质基础,指出震磁效应对于研究震源前兆的特殊意义,文中还介绍了１９７６唐山地震观测到震源前兆的部分实际地磁资料。  相似文献   

The　Epi－continental　arc　of　Southeast　China　and　relevant　earthquakes     

徐嘉炜 《地震学报(英文版)》1996,9(4):565-571

ＴｈｅＥｐｉ┐ｃｏｎｔｉｎｅｎｔａｌａｒｃｏｆＳｏｕｔｈｅａｓｔＣｈｉｎａａｎｄｒｅｌｅｖａｎｔｅａｒｔｈｑｕａｋｅｓＪＩＡ－ＷＥＩＸＵ（徐嘉炜）ＤｅｐａｒｔｍｅｎｔｏｆＲｅｓｏｕｒｃｅａｎｄＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎｃｅｓ,ＨｅｆｅｉＵ...  相似文献   

北京及邻区微震活动的初步分析     

赵永  高艳玲 《地震地磁观测与研究》1996,17(5):42-49

通过对北京遥测地震台网近年来记录到的北京及邻区地震的震中分布,地震活动频度及能量释放强度的分析,得到本区地震活动在时间分布上具有“聚堆性”。在年发震频度,地震强度和能释放方面均具有双峰值特征,并且具有较好的一致性和同步性,在空间分布上具有条带特征,且形成北东～南西和北西～南东的两条相互交汇的条带。又通过统计分析得到本区发震概率最大的时间段是每年的１０月前后,而地震主要发生在北西～南东带上。  相似文献   

Hierarchical decomposition of variance with applications in environmental mapping based on satellite images     

Ferenc Csillag  Sándor Kabos 《Mathematical Geology》1996,28(4):385-405

A quadtree-based image segmentation procedure (HQ) is presented to map complex environmental conditions. It applies a hierarchical nested analysis of variance within the framework of multiresolution wavelet approximation. The procedure leads to an optimal solution for determining mapping units based on spatial variability with constraints on the arrangement and shape of the units. Linkages to geostatisiics are pointed out, but the HQ decomposition algorithm does not require any homogeneity criteria. The computer implementation can be parameterized by either the number of required mapping units or the maximum within-unit variance, or it can provide a spectrum of significances of nested ANOVA. The detailed mathematical background and methodology is illustrated by a salt-affected grassland mapping study (Hortobágy, Hungary), where heterogeneous environmental characteristics have been sampled and predicted based on remotely sensed images using these principles.  相似文献   

皖南变质岩中的疑源类、孢粉化石组合及其地质意义   总被引：9，自引：0，他引：9  

陈冠宝  陶正  石永红  徐树桐 《地质学报》1996,70(4):374-382,T002

皖南变质岩区地层原被认为属江南古陆的一部分,时代定为中、晚元古代。本文根据其中所含的Asperatopsophosphaera?sp.,Trachysphaeridium sp.,Nucellosphaeridium sp.,Lophosphaeridium sp.,Leiosphaeridia sp.,Baltisphaeridium spp.,Micrhystridium spp.和scolecodonts等疑源类和其它微体化石及笔者等以前发现的Lingulacea总面貌反映的时代,判断其中部分变质地层的时代应为晚元古代—早古生代和早古生代。同时还根据Crassispora sp.,Kraeuselisporites sp.和Lueckisporites ef.virkkiae Potonie ＆ Klaus,Triquitritessp.等孢粉化石组合面貌反映的时代,推断其中尚有一部分为晚古生代地层。因此认为本区是一个从晚元古代—早古生代开始到中生代结束的碰撞型造山带,而不是一个古陆。  相似文献   

关于海平面上升及其环境效应   总被引：12，自引：0，他引：12  

陈梦熊 《地学前缘》1996,3(2):133-140

沿海地区地质环境复杂。由于国民经济的迅速发展,人类活动日益增多,对地质环境进一步造成严重的不利影响。特别是“温室效应”引发的海平面上升,使各种地质灾害更加激化。文章详细探讨了海平面上升的影响因素,理论海平面与相对海平面升降幅度的评估,以及海平面上升所造成的地质环境效应与相应的防治对策,特别强调控制沿海城市地面沉降,以减轻海平面相对上升造成的危害,具有特殊而重要的意义。  相似文献   

Overbreak and underbreak in underground openings Part 2: causes and implications   总被引：7，自引：0，他引：7  

J. A. Ibarra  N. H. Maerz  J. A. Franklin 《Geotechnical and Geological Engineering》1996,14(4):325-340

Summary The newly developed light sectioning method has been used to investigate some of the causes and costs of overbreak and underbreak. Investigations at the Aquamilpa Hydroelectric Project in Mexico have shown decreased overbreak and increased underbreak as a result of increased rock quality and decreased explosive energy. A new measure of explosive energy, the perimeter powder factor (PPF), has been defined and shown to be useful in the context of tunnel-wall rock damage. Tentative results indicate that explosive energy (PPF) may be a more important factor in producing underbreak, whereas rock quality may be a greater factor in producing overbreak. A site-specific equation is given for predicting overbreak or underbreak as a function of rock quality and explosive energy, with an evaluation of the cost of underbreak and overbreak.  相似文献