On the Large Scale Spatial Heterogeneity of Great Shallow Earthquakes and Plate Coupling Mechanism in Chinese Mainland and Its Adjacent Areas

Research on the large scale spatial heterogeneity of great intraplate shallow earthquakes on the Chinese mainland and adjacent areas discussed in this paper shows that(1)there are four main high seismicity areas:the North China seismic area in the eastern part of China(30°-42°N),the Southeastern Coast seismic area in the eastern part of China(19°-25°N),the North-South seismic area in the western part of China and its adjacent areas(Burma-China-Mongolia),and the Central Asian seismic area in the western part of China and its adjacent areas(Pamir-Tianshan Mountains-Baikal);(2)the four intraplate seismic areas that are approximately perpendicular to those sections of the Eurasia plate boundary that surrounds the Chinese mainland and its adjacent areas,where the Eurasia plate has a strong seismic coupling with the North America-Pacific Ocean-Philippine Sea plate and the India plate; and(3)the large scale spatial heterogeneity of intraplate seismicity in China and its adjacent areas that might be control     

三十余年来云南气压涨落的致震方式和阈值研究

本文以孕震系统在爆发前夕的外敏性及外力的非线性作用为物理基础，对大气扰动下的地震爆发问题进行了初步探讨，不仅给出了三十余年来整个云南气压场的归－化原则以及四次７级大震前震中附近的气压巨涨落特征，而且还对滇东，滇西北，滇西南等地区分带归纳建立了具有实用价值的气发震指标。这些自然共性的揭示，既是对外力效应的认证，也丰富了短临地震预报的科学依据。     

1971—2018年黑龙江省玉米需水量与有效降水量耦合度演变特征

基于1971—2018年黑龙江省69个气象台站逐日气象资料, 利用联合国粮农组织(FAO)推荐方法计算玉米需水量, 应用美国农业部土壤保持局推荐方法计算有效降水量, 采用Mann-Kendall检验、GIS反距离加权插值等方法分析黑龙江省玉米需水量与有效降水量耦合度及其演变特征。结果表明: 黑龙江省玉米拔节以前生育时段大部地区有效降水增加, 拔节以后各生育阶段大部地区有效降水呈减少趋势, 不同区域变化趋势略有不同。受风速变小和日照时间减少等气象因子影响, 黑龙江省大部地区玉米需水量减少, 东部减速最快, 北部最慢。黑龙江省中部和东北部玉米需水量与有效降水量耦合度较高, 西部较低; 拔节以前耦合度较低, 拔节以后较高。各区域耦合度均呈“两落两起”变化趋势, 2011—2012年为耦合度由低到高明显突变点。     

简评陆面过程模式

在这篇文章中,阐述了陆面过程对天气,气候和大气环流的影响以及陆面过程模式在大气数值模拟中的重要性;回顾了陆面过程模式的发展历史;分析了一些陆面过程模式之间的主要结构差别;讨论了目前陆面过程模式的发展水平和未来的发展方向;简述了大气中尺度模式与陆面过程耦合的必要性以及当今耦合模式的研究现状。     

The application of the transient electromagnetic method in hydrogeophysical surveys

The transient electromagnetic (TEM) method has been used extensively for hydrogeophysical exploration in Denmark for the past decade. Innovative instrumentation combined with multi-dimensional modelling and interpretational insights based on experience gained through numerous case studies have proven to be a successful strategy. In the case study reported here, the combination revealed an unknown and unexpected buried valley complex. Drill hole data were in good agreement with estimates of both the bearings and depths of valleys defined by the TEM surveys. The Pulled Array Transient Electromagnetic (PATEM) system was built to provide high data density for increased lateral resolution. A High moment Transient Electromagnetic (HiTEM) system was developed for delineation of aquifers to depths up to 300 m. Because both of these systems provide high data density, data quality can be assessed as part of the interpretational strategy. When acquiring TEM measurements in areas as densely populated as the Danish countryside, precautions must be taken to minimize coupling between the TEM system and man-made conductors. Modelling the slope of the flanks of buried valleys has challenged the adequacy of the one-dimensional (1-D) assumption for inversion of TEM data. The study shows that for a valley structure in a low-resistive layer, the 1-D assumption is sufficient to track the presence of rather steep slopes. For a valley structure in a high-resistive layer, however, the insensitivity of the TEM method to resistors makes it difficult to determine a slope with a 1-D inversion, and only the overall structure is defined.     

宁夏中部干旱带生态变化与沙尘暴发生的关系分析

利用TM遥感资料, 结合8大类土地详查资料, 基本查清了位于宁夏中部干旱带具有代表性的沙尘暴高发区盐池县20世纪90年代年际变迁量化特征。分析表明, 盐池县90年代初期的生态状况明显好于末期。气候干旱是导致生态变化的主要原因, 但人为活动如大量开垦耕地、过牧及滥挖甘草等也是重要因子。依据沙尘暴的成因, 通过对近30年盐池县沙尘暴个例多源资料综合分析, 局部治理整体恶化的生态现状导致了沙尘暴起暴阈值的明显下降, 即近30年来沙尘暴在宁夏中部的干旱地带发生机率已显著提高。由于造成我国西北地区土地荒漠化的气候、水资源短缺、土地资源超载等因素在可预见的一个相当长的时期将难以得到较大的改善, 且干旱区的生态环境具有脆弱性、易损性、难复性等特点, 该文通过较全面客观的量化分析, 初次提出今后我国西北地区的沙尘暴发生机率应处在上升的态势之中。     

AutoPaCA:耦合过程-模式的城镇空间增长模拟模型

理解城镇增长过程、模式、机理并预判未来发展趋势,对优化城镇空间布局,促进城市可持续发展有重要意义。元胞自动机模型（Cellular Automata, CA）是研究城镇增长过程、模式的有效技术手段,但传统CA模型对城镇增长过程和空间模式的协同考虑不足。本研究构建了基于斑块（Patch）的城镇CA模型AutoPaCA,实现对城镇增长过程及空间模式的协同表征和精细控制,将城镇增长过程分为边缘增长和跳跃增长两种形式,并实现了对不同形式下城镇斑块位置、形状和面积大小的精细控制,同时考虑城镇空间模式的集聚性、整体形态及空间约束。此外,还提出使用景观格局分析法分析历史时期城镇增长过程和模式,并结合遗传算法实现对模型参数的地域化自动校正,降低人为主观因素对模拟结果的影响。将模型应用于长沙市1995—2035年的城镇增长模拟与多情景分析。结果表明,构建的AutoPaCA模型可以取得较好的模型精度,200次模拟结果的互异邻域相似性指数均值达到0.486;在生态保护情景下,长沙市城市内部生态结构保存完好,且表现出更为明显的长株潭一体化趋势,说明本研究提出的AutoPaCA模型及参数校正方法是有效的。     

Coupling action of rainfall and vehicle loads impact on the stability of loess slopes based on the iso-water content layer

To clarify the changes in slope stability of loess slopes under the coupling action of rainfall and vehicle loads. Experiments with different water contents under different environmental conditions were carried out indoors, and the relationship function between water content and shear strength parameters was obtained; Secondly, based on Geostudio, an equivalent layered calculation model of water content-strength parameters of loess slope was established, the variation law of soil sample matrix suction with volumetric water content was measured by volumetric pressure plate tester. Finally, by using a combination of finite element analysis of saturated/unsaturated seepage and limit equilibrium analysis of slope stability, the SLOPE/W module in the modeling software GeoStudio is used to calculate and analyze the effects of vehicle loads, rainfall intensity, rainfall duration, and other working conditions on the stability of loess slopes, respectively. The results show that when the lane is in the middle of the slope, the vehicle load parameters have little effect on the uphill stability, but have a greater impact on the downhill; With the increase in rainfall, the change curves of the slope safety coefficient gradually overlap when the vehicle loads are four-axis,five-axis, and six-axis. This shows that when studying the change of slope safety factor under the dual influence of vehicle loads and rainfall, rainfall is the main cause of slope stability; The change rate of slope safety factor increases gradually with the increase of rainfall, and the change trends of the upper, lower and overall parts of the slope are similar.     

Geophones on blocks: a prototype towable geophone system for shallow land seismic investigations

In recent years some authors have given a certain amount of attention to towed seismic reflection acquisition systems. Based on some of these works we sought to design and test a system making use of currently available geophones instead of specifically designed sensors as employed in some previous works. Thus, bearing in mind that the geophone's characteristics are achieved in the conditions that they are originally designed to be employed in, i.e., coupled with a spike driven into the ground, we devoted our attention to some of the variables involved in the geophone's performance, namely the total weight, the effect of a spikeless geophone and the surfaces on which the geophone is placed. Previously, we had experimentally verified some variations in the signal response due to coupling geophones in different surface materials, such as hard soil, asphalt and concrete pavement and we noticed that these surface materials were in fact an important factor in the overall response. Hence, these materials, or as we also called them coupling agents, could be employed as a base material in the construction of a mobile seismic acquisition device composed of blocks of a certain size, on which the geophone would be then inserted and thus making it into a spikeless surface towable system. Therefore, various materials were tested in order to select one that could maintain a similar fidelity to that of the spike coupled geophone and thus contribute towards building a more time efficient and towable geophone and block system. Pinging tests revealed variations in the coupling frequency and damping characteristics of each coupling agent and from all of these tested materials one was selected for field comparative tests with the normally planted geophones with spike coupling. Finally a seismic reflection profile was acquired simultaneously with both systems, i.e., spike coupling versus cement block coupled geophones. This field test showed similar results in terms of signal levels and frequency content and therefore it was possible to observe the presence of the same reflectors and other seismic events in either of the time sections. With this experiment we propose not only a system that allows a time efficient seismic field operation but we also aim to encourage more research into the response dependency of the coupling agent of which the towable base block is made of.     

核幔边界动力学——地球自转十年尺度波动

总结了地球核幔边界动力学有关研究的新进展,如核幔边界的特性、核幔边界的地形起伏、核幔边界附近地幔对流格局和地球外核顶部的流场等。从地核—地幔之间的耦合出发,讨论了地球自转十年尺度的波动问题,简述了核幔之间电磁耦合、粘滞耦合和地形耦合对十年尺度波动影响的基本理论。提出在该项研究中应以综合分析为基础,开展多学科的联合、交叉研究的途径以深化对地球自转十年尺度波动机理的认识。