欧洲地震委员会第24届大会综述

欧洲地震委员会第２４届大会于１９９４年９月１９－２４日在希腊首都雅典召开，出席这次大会的代表共３８０人。会上宣读和张贴论文５４１篇，内容主要涉及地震预测研究、地震活动性、工程地震、震源物理和数据采集、理论与解释等。本文综述这次大会的情况。     

中国—欧洲共同体地震科学合作项目“北京西北延庆—怀来盆地地震学研究”进展

为探索强烈地震的前兆，在欧洲共同体的支持下，中国和英国的地震学家共同在北京西北的延庆—怀来盆地建立了一个数字地震台网．延庆—怀来数字地震台网由５个野外台和一个中心台构成。研究工作的重点是探索强烈地震前地震横波分裂现象中的参数变化．１９９５年４月３０日台网建成并投入运作．１９９５年７月下旬．怀来地区发生ＭＬ＝４．０地震及其余震，延庆—怀来数字地震台网很好地记录了这一地震序列。初步的分析表明．这一地震序列表明了怀来县城以南６—８ｋｍ处，怀来盆地南缘下部的断层活动，它与怀来地区地表有明显出露的主要断裂没有明显的直接联系。     

Beltanelloides podolicus 在中国上震旦统首次发现

Beltanelloidespodolicus可谓球形藻群体化石之最大者,压扁圆盘体直径3-30mm,呈炭质膜保存。与其一起出现的化石还有许多高级藻类和动物化石。它们的发现为扬子地台上震旦统与东欧地台文德期地层的对比又添一证据。     

Green hope or greenwash? The actions of the European Union at the World Summit on sustainable development

This article examines whether the European Union (EU) could be seen as a normative power at the recent World Summit on Sustainable Development. We explain how the EU operationalised its commitment to the concept of sustainable development before highlighting the impact the EU had on the final summit outcomes. It shows that although in many areas the EU was able to offer leadership, internal policy coherence prevented it fully being able to develop that role and thus fully promoting the norm of sustainable development.     

Combining field and modelling techniques to assess rockfall dynamics on a protection forest hillslope in the European Alps

Adequate management of a mountain forest that protects downslope areas against impacts of rockfall requires insight into the dynamics of the hillslope environment. Therefore, we applied a combined approach, using field and modelling techniques, to assess the determining factors for rockfall source areas, rockfall tracks and rockfall runout zones on a forested slope in mountainous terrain. The first objective of this study was to understand why rockfall occurs in the study area. The second objective was to translate the knowledge obtained in the field into a model that simulates rockfall dynamics on a forested slope realistically. The third objective was to assess which hillslope characteristics primarily determine the distribution of active rockfall tracks. To achieve these objectives, we made a geomorphological map of the whole study area, and we measured the major discontinuity planes in the bedrock that are exposed in the rockfall source areas. Furthermore, a test site for simulation modelling within the larger study area was defined in which both a forest and a hillslope inventory were carried out. The available data and our developed rockfall simulation model allowed us to assess the slope characteristics that mainly determine the distribution of areas affected by rockfall. We found that in decreasing order of importance, both standing and felled trees, the surface roughness and rockfall resistant shrubs primarily determine the distribution of rockfall-affected areas. Simulation tests without a forest cover produced similar rockfall runout zones as fossil rockfall events identified in the field. We believe that the combined field and modelling approach is a prerequisite for understanding how forests can protect against rockfall.     

The Glueckstadt Graben, a sedimentary record between the North and Baltic Sea in north Central Europe

The Glueckstadt Graben is one of the deepest post-Permian structures within the Central European Basin system and is located right at its “heart” at the transition from the North Sea to the Baltic Sea and from the Lower Saxony Basin to the Rynkoebing–Fyn High.The Mesozoic to recent evolution is investigated by use of selected seismic lines, seismic flattening and a 3D structural model. A major tectonic event in the latest Middle–Late Triassic (Keuper) was accompanied by strong salt tectonics within the Glueckstadt Graben. At that time, a rapid subsidence took place within the central part, which provides the “core” of the Glueckstadt Graben. The post-Triassic tectonic evolution of the area does not follow the typical scheme of thermal subsidence. In contrast, it seems that there is a slow progressive activation of salt movements triggered by the initial Triassic event. Starting with the Jurassic, the subsidence centre partitioned into two parts located adjacent to the Triassic “core.” In comparison with other areas of the Central European Basin system, the Glueckstadt Graben was not strongly affected by additional Jurassic and Cretaceous events. During the late Jurassic to Early Cretaceous, the area around the Glueckstadt Graben was affected by relative uplift with regional erosion of the elevated relief. However, subsidence was reactivated and accelerated during the Cenozoic when a strong subsidence centre developed in the North Sea. During Paleogene and Quaternary–Neogene, the two centres of sedimentation moved gradually towards the flanks of the basin.The data indeed point toward a control of post-Permian evolution by gradual withdrawal of salt triggered by the initial exhaustion along the Triassic subsidence centre. In this sense, the Glueckstadt Graben was formed at least partially as “basin scale rim syncline” during post-Permian times. The present day Hamburger, East and Westholstein Troughs are the actual final state of this long-term process which still may continue and may play a role in terms of young processes and, e.g., for coastal protection.     

Carbonyls and nonmethane hydrocarbons at rural European sites from the mediterranean to the arctic

Results of regular measurements during 1992–1995 of hydrocarbons and carbonyl compounds for a number of rural European monitoring sites are presented. The measurements are part of the EMEP programme for VOC measurements in Europe. In addition, several years of regular measurements are included from the Norwegian stations Birkenes at the south coast, and Zeppelin Mountain on Spitsbergen in the Arctic. The sampling frequency has been about twice per week throughout the years, implying that a substantial amount of measurement data are available. Almost all the chemical analyses have been performed by one laboratory, the EMEP Chemical Co-ordinating Centre located at NILU, which avoids problems of intercomparison and intercalibration among different laboratories. For the measured concentrations both seasonal and geographical variations are shown and discussed. The diurnal cycles of the hydrocarbon concentrations were studied in detail at one site, where the grab samples by EMEP where compared with a parallel continuous sampler, operated by EMPA, Switzerland. Hydrocarbons linked to natural gas and fuel evaporation become well mixed into the Arctic in the winter, whereas combustion products show a latitudinal gradient. The sum of oxygenated species constitutes about 5–15% of the sum of C₂–C₅ hydrocarbons in winter. In summer they are almost equal in magnitude, consistent with an increasing oxidation of hydrocarbons.     

Genetic geographies. A historical comparison of agrarian modernization and eugenic thought in Germany, the Soviet Union, and the United States

The article deals with the role of genetics in the state-led agricultural modernization efforts that took place in different industrialized countries during the course of the 1920s and 1930s. A comparison between Germany, the Soviet Union and the United States shows substantial similarities in their attempts to increase the productivity of agriculture on different geographical scales. Following advances in scientific knowledge about the geography of cultivated plants, these countries sent out numerous expeditions to collect plant breeding material from all over the world. At the same time, states tightened their grip on farmers’ and breeders’ activities inside the country by establishing legal rules for the use of plant varieties and seed. But this was only one side of a larger “genetic modernization” project. In all three countries, concepts of agricultural modernization were substantially linked to social-darwinist thought which embraced programs of eugenics and “racial hygiene”. These links are outlined for each of the cases, highlighting the widely differing intermingling of scientific concepts and terminologies with political ideologies. It is then discussed what role geography and in particular geopolitical thinking of the time were to play in the development of “genetic modernization”, and more specifically, with regard to the nexus between agriculture and eugenics. While the discipline’s involvement in both fields remained comparably marginal in practical terms, clearly there were conceptual contributions toward the development of the broader field. Going back to Ratzel’s and Kjellén’s work, it is argued that geography had an important role in the establishment of a political field in which ideas of managing human reproduction were fused with concepts of economic development and environmental determinism.