Numerical simulation of strong ground motion for the <Emphasis Type="Italic">M</Emphasis><Subscript>s</Subscript>8.0 Wenchuan earthquake of 12 May 2008

The Wenchuan earthquake of 12 May 2008 is the most destructive earthquake in China in the past 30 years in terms of property damage and human losses. In order to understand the earthquake process and the geo-morphological factors affecting the seismic hazard, we simulated the strong ground motion caused by the earthquake, incorporating three-dimensional (3D) earth structure, finite-fault rupture, and realistic surface topography. The simulated ground motions reveal that the fault rupture and basin structure control the overall pattern of the peak ground shaking. Large peak ground velocity (PGV) is distributed in two narrow areas: one with the largest PGV values is above the hanging wall of the fault and attributed to the locations of fault asperities and rupture directivity; the other is along the northwestern margin of the Sichuan Basin and caused by both the directivity of fault rupture and the amplification in the thick sediment basin. Rough topography above the rupture fault causes wave scattering, resulting in significantly larger peak ground motion on the apex of topographic relief than in the valley. Topography and scattering also reduce the wave energy in the forward direction of fault rupture but increase the PGV in other parts of the basin. These results suggest the need for a localized hazard assessment in places of rough topography that takes the topographic effects into account. Finally, had the earthquake started at the northeast end of the fault zone and ruptured to the southwest, Chengdu would have suffered a much stronger shaking than it experienced on 12 May, 2008. Supported by the U.S. National Science Foundation (Grant Nos. EAR 0738779 and OCE 0727919), the National Basic Research Program of China (Grant No. 2004CB418404), and partially by the National Nature Science Foundation of China (Grant No. 40521002)     

中国东部史前地震事件的的识别问题

中国东部地区气候湿润,物理化学风化作用强烈,加上地震周期长,人类活动频繁,地质事件遗迹难寻;另一方面,东部地区经济蓬勃发展,建(构)筑物和公众地震安全要求攀升.本文为解决这一日益尖锐矛盾作了相应综述和分析,并提出了一些建议:从经验预报统计样本局限性分析入手,综述史前地震识别标志和事件时序的分析研究现状,在此基础上提出了中国东部地区史前地震事件强化研究思路,即充分利用大规模考古发掘和工程所揭露的机遇,抢救性编录、分析.同时与考古、地质等相关部门联手,反演并重构全新世以来天然变形事件时序,用于弥补经验性预报的样本局限,从而科学预测地震趋势.作者的初步实践表明,这一思路是可行的,通过持之以恒的努力,有望达到预期目标.     

Ionospheric electromagnetic perturbations observed on DEMETER satellite before Chile M7.9 earthquake

Based on the ionospheric electromagnetic data observed on DEMETER satellite of France, the ionospheric electromagnetic signals were analyzed within 10 days before Chile M7.9 earthquake on November 14, 2007. It is found that, low frequency electromagnetic disturbances began to increase in a large scale of latitude, and reached to a maximum one week prior to the earthquake, and at about three days before the quake, the peak values shifted to lower latitude. Taking three days as a group, spatial images of a fe...     

Features and mechanism of neotectonic deformation of the Xishan fault system west of Urumqi

We have made careful field investigation and trench exploration to the Xishan fault system in west of Urumqi,and an integrated analysis in conjunction with data of deep seismic sounding.Our result suggests that under the SN-oriented compressive stress,the Xishan block moves steadily toward the Tianshan Mountains in south,resulting in southward thrust-slip and crustal shortening,particularly the southward thrust of the Xishan fault which serves as the main boundary in south.North of the Xishan fault are the ...     

Nonlinear seismic soil–pile–structure interactions: Shaking table tests and FEM analyses

In this paper, a soil–pile–structure model is tested on a shaking table subject to both a sinusoidal wave and the acceleration time history of the scaled 1940 El Centro earthquake. A medium-size river sand is compacted into a 1.7-m-high laminar rectangular tank to form a loose fill with a relative density of 15%. A single-storey steel structure of 2.54 ton is placed on a concrete pile cap, which is connected to the four end-bearing piles. A very distinct pounding phenomenon between soil and pile is observed; and, the acceleration response of the pile cap can be three times larger than that of the structural response. The pounding is due to the development of a gap separation between soil and pile, and the extraordinary large inertia force suffered at the top of the pile also induces cracking in the pile. To explain this observed phenomenon, nonlinear finite element method (FEM) analyses with a nonlinear gap element have been carried out. The spikes in the acceleration response of the pile cap caused by pounding can be modeled adequately by the FEM analyses. The present results suggest that one of the probable causes of pile damages is due to seismic pounding between the laterally compressed soil and the pile near the pile cap level.     

佘山地震台防雷技术研究与应用

在详细分析雷电灾害特征的基础上,阐述了防雷工作的主要技术手段。并针对地震台站的构成特点,研究了台站综合防雷系统的设计方法和技术措施。同时,以余山地震台为例,具体说明了防雷措施的应用方法及应用效果。     

宁夏数字地震观测网络项目之网络设计与综合评价

宁夏数字地震观测网络项目信息服务分项项目组作为整个网络系统集成组,在信息网络系统的建设过程中,依据不同地震观测项目对信道速率、连续率、实时性、网络延时等通信要素的不同要求,考虑到不同节点的基础通信条件的差异,在采用平面星型网络拓扑结构作为总的通信策略的同时,实地考察、科学分析、统一规划、综合布局,对不同类型的节点分别采用不同的通信信道组合策略作为节点的接入方式,采用以OSPF为主要路由协议的多路由协议集成,全面解决了宁夏数字地震观测网络项目的整体通信和路由融合问题,同时也为其他观测项目的数据传递和汇聚提供了可靠的通信网络平台。     

ESR dating of dental enamel from Middle Palaeolithic levels at Lazaret Cave,France

ESR dating was carried out on Cervus elaphus tooth enamel samples from the depositional sequence of Lazaret Cave, Nice, France. The deposits contain Anteneandertal hominid fossils associated with abundant lithic artefacts and faunal remains. Three samples from the Mousterian occupations in complex CIII (Fouille d'entrée) yielded early uptake (EU) ages between 108 and 125 ka and linear uptake (LU) ages between 133 and 160 ka. Seven samples from the Acheulian levels in the upper part of the complex CII (Fouille d'entrée and Fouille centre) gave EU ages between 113 and 165 ka and LU ages between 147 and 210 ka, with weighted means at 131 ± 7 and 165 ± 9 ka, respectively. The results of six enamel samples from the lower Acheulian levels at Locus VIII, another place in the cave, were discarded because of their decreasing tendency with depth. The US–ESR combination method was also applied and the CSUS–ESR dates were calculated using the ESR-DATA program. Altogether, the data suggest that the Lazaret Acheulian and Mousterian occupations were rapidly formed during OIS 6.     

白云岩体表生成岩裸露期古风化壳岩溶的规模

白云岩体表生成岩裸露期古风化壳岩溶对白云岩体古岩溶储渗体的形成至关重要。表生成岩裸露期古风化壳岩溶可形成地表残积层和表层之下大小不等的溶蚀空间。地表残积层与上覆盖层间可成为油气的储渗空间和通道,表层之下大小不等的溶蚀空间则可被塌积岩、冲积岩、填积岩和淀积岩充填,但其内常可保存部分孔隙,并为后来的埋藏溶解提供流体扩溶的初始空间和流体流动的通道。野外露头和井下岩心中的大量现象和事实说明,白云岩体表生成岩裸露期古风化壳的规模远小于石灰岩体。最主要原因是白云岩(石)可溶性远较石灰岩(方解石)小,同样组构的白云岩的物理力学强度亦较石灰岩小。白云岩体本身的岩性和组构、层理类型、泥质含量、构造裂隙的发育程度等都会影响裸露期古风化壳的规模。     

虾蟹类生物能量学研究进展

虾蟹类生物能量学（Bioenergetics）是研究能量在虾蟹类体内转换的一门学科,其中心问题是研究虾蟹类体内能量收支各组分之间的定量关系以及环境因子（温度、盐度和pH等）、营养因子（饵料种类、蛋白质、脂肪和碳水化合物等）和内源因子（发育阶段和体质量等）对这些关系的影响,探讨生物调节其能量分配的生理生态学机制。Klein最早提出了能量在虾蟹类体内流动和转换的基本模型,该模型可归纳为以下能量收支式：C=G＋R＋U＋F＋E,式中C为摄食能,G为生长能,R为呼吸能,U为排泄能,F为排粪能,E为蜕壳能。