发挥地震学会优势促进防震减灾工作--关于加强山西省地震学会管理工作的几点思考

随着我国机构改革的不断深入和社会主义市场经济体制的逐步建立和完善，地震学会同其他社会团体一样将成为现代社会的支柱之一。以山西省地震学会目前的工作现状为例，指出学会在管理体制、运行机制和活动方式等方面存在的问题，提出了发展思路及建议。     

2000年以来中国大陆5级以上地震近源区的相继发震特征与预测

通过对中国大陆除新疆和东北深震区以外的主要地区2000年以来5级以上地震活动特征的研究发现,5级以上地震近源区的相继发震是某些区域地震活动的重要特征。依据这一特征可以对今后研究区内5级以上地震的后续地震作中期预测。     

陕西农村房屋抗震设防现状及对策

陕西省近年来发生的泾阳和石泉两次地震造成了农村房屋不同程度地破坏。通过对这两次地震的现场考察,分析总结了陕西农村房屋抗震设防现状及存在的主要问题,并提出了相应的改进措施及对策建议。     

试论实施防震减灾社会动员的途径与方法

0前言中国是一个多地震国家,频繁而严重的地震灾害给人民生命和财产带来了巨大的损失,防震减灾任务任重而道远。回良玉副总理2004年在全国防震减灾工作会议讲话中指出:“防震减灾是全社会共同的责任,要广泛动员社会各方的力量,积极投入到这项事业中来,使防震减灾逐步成为全社会的自觉行动。”因此,总结近40年我国防震减灾工作和改革开放的实践经验,对社会公众进行各种防震减灾宣传教育,广泛动员全社会力量,建立健全防震减灾社会动员机制,增强全社会防震减灾意识,是提高我国综合防震减灾能力,有效地促进地震灾害综合防御各项措施落实的重要途…     

Estimating severity of liquefaction-induced damage near foundation

An empirical procedure for estimating the severity of liquefaction-induced ground damage at or near foundations of existing buildings is established. The procedure is based on an examination of 30 case histories from recent earthquakes. The data for these case histories consist of observations of the damage that resulted from liquefaction, and the subsurface soil conditions as revealed by cone penetration tests. These field observations are used to classify these cases into one of three damaging effect categories, ‘no damage’, ‘minor to moderate damage’, and ‘major damage’. The potential for liquefaction-induced ground failure at each site is calculated and expressed as the probability of ground failure. The relationship between the probability of ground failure and the damage class is established, which allows for the evaluation of the severity of liquefaction-induced ground damage at or near foundations. The procedure presented herein represents a significant attempt to address the issue of liquefaction effect. Caution must be exercised, however, when using the proposed model and procedure for estimating liquefaction damage severity, because they are developed based on limited number of case histories.     

Dynamic theory of rigid-plasticity

This paper deals with an analysis method for the response and motion of soil-like rigid-plastic bodies under seismic loading conditions. A continuity condition to determine the acceleration distribution within the rigid-plastic body when the failure occurs during seismic motions is proposed. Combining this continuity condition of acceleration and the ‘Generalized Limit Equilibrium Method (GLEM)’, the responses of the earth structure during seismic motions as well as the permanent displacements can be obtained, where GLEM is one of the limit equilibrium methods proposed by the authors for static problems and providing the approximate solution for Kötter's equation. The theoretical formulation of the method, the illustrative examples, and some comparisons between the analytical and experimental results are demonstrated.     

Non-destructive monitoring of trace element levels in short-tailed albatrosses (Phoebastria albatrus) and black-footed albatrosses (Phoebastria nigripes) from Torishima Island, Japan using eggs and blood

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl and Pb) were determined in abandoned eggs of short-tailed albatrosses and abandoned eggs and blood of black-footed albatrosses from Torishima Island, Japan in 2002. Mercury concentration was highest among the toxic elements in egg content of both the two species. In some egg contents of black-footed albatrosses, Hg concentrations were higher than the threshold level that may cause decreased hatchability and aberrant nesting behavior in some avian species. Concentrations of Cd in egg content and Ba in egg content and shell increased with an increase in egg breadth/length ratio, whereas Hg in egg content showed an opposite trend in black-footed albatrosses. Since egg breadth/length ratio is known to increase with the age of mother bird, this result may imply that concentrations of these elements in eggs vary with age of mother bird. In blood of black-footed albatross chicks, concentration of Hg was highest among the toxic elements and the Hg concentration showed an increase in the later growth stages. In contrast, concentration of Sr in blood decreased with growth stage. Since the behaviour of Sr is similar to that of Ca in animals, it is conceivable that Sr was used along with Ca for the formation of bone.     

The GGOS as the backbone for global observing and local monitoring: A user driven perspective

A key geodetic contribution to both the three Global Observing Systems and initiatives like the European Global Monitoring for Environment and Security is an accurate, long-term stable, and easily accessible reference frame as the backbone. Many emerging scientific as well as non-scientific high-accuracy applications require access to an unique, technique-independent reference frame decontaminated for short-term fluctuations due to global Earth system processes. Such a reference frame can only be maintained and made available through an observing system such as the Global Geodetic Observing System (GGOS), which is currently implemented and expected to provide sufficient information on changes in the Earth figure, its rotation and its gravity field. Based on a number of examples from monitoring of infrastructure, point positioning, maintenance of national references frames to global changes studies, likely future accuracy requirements for a global terrestrial reference frame are set up as function of time scales. Expected accuracy requirements for a large range of high-accuracy applications are less than 5 mm for diurnal and sub-diurnal time scales, 2–3 mm on monthly to seasonal time scales, better than 1 mm/year on decadal to 50 years time scales. Based on these requirements, specifications for a geodetic observing system meeting the accuracy requirements can be derived.     

A new approach of single epoch GPS posi- tioning for landslide monitoring

Introduction China is a country with many landslides and debris flows. These disasters bring out a large amount of losses of life and property. It is significant to predict landslide incident by monitoring the deformations of these landslides. At past, triangulation and trilateration are traditional tools, but it is very difficult for them to realize real-time monitoring, and it is more dangerous for obser- vation workers when the deformation becomes larger. Because of many advantages such as…     

Dike intrusion associated with the 2000 eruption of Miyakejima Volcano, Japan

The model for the 2000 dike intrusion event between Kozushima and Miyakejima volcano, Japan, was reinvestigated. After the sudden earthquake swarm in Miyakejima volcano, a dike intrusion of large volume was detected by the nationwide GPS network (Geonet). The displacements detected with GPS stations over an area with a radius of about 200 km shows a distribution that is consistent with the dike source being located near Miyakejima volcano.The dike was intruded northwestwards between Miyakejima and the neighboring Kozushima volcano. We searched for the parameters in the models that reproduce the regional displacements due to dike intrusion between Miyakejima and Kozushiima islands. We tested three models, (1) the model with a single dike, (2) the model with a dike and a point dislocation source which represents a creep dislocation source and (3) the model with a dike and a deflation source which represents a magma reservoir. Though all three models can match the horizontal displacements near the source area, model 1 fails to reproduce the regional displacements in the central part of Japan. Both models 2 and 3 can reproduce the regional displacement for horizontal components. Model 3 produces slightly better results than model 2 for vertical components. The balance in the volume budget for models 2 and 3 is also consistent with the observations. These results show that we cannot distinguish between the two models using only GPS observation. As there is no direct evidence for such a large creep or ductile source (corresponds to M7 or more) as proposed in model 2 and the active seismic region migrated back and forth within the linear swarm region, the model with a dike and a deep magma source is preferable. For the deflation point source, we obtained a deflation volume of 1.5 km³ at the depth of 20 km below the dike. An additional ~0.95 km³ of volume loss through caldera collapse and edifice deflation took place at Miyakejima. We conclude that the magma that intruded the dike came in part from below Miyakejima and in part from below the sea floor between Miyakejima and Kozushima, perhaps from reservoirs at the Moho.Editorial responsibility: S Nakada, T Druitt