北京地区地震地质条件及地震地面运动反应分析

本文利用北京市地下地质、地震及震害等资料,选定了城区西北部震害异常带下伏的基岩凹陷作为研究对象,应用经过扩展的SAP5二维结构动力分析程序进行了动力有限元分析,结果表明:1.二维动力有限元分析解决了不规则的埋藏基岩地形对地面地震反应问题。2.埋藏基岩地形的起伏对地震地面运动的影响是明显的。3.既便只输入S波,也有可观的竖向运动分量产生。4.埋藏基岩凹陷地形的地震地面运动反应与震害异常带有成因上的联系。     

吉林台电站场地地震活动性分析

本文利用目前较新的方法对吉林台电站坝区地震活动性进行了多方面的探讨。资料分析与处理‘包括绘图均在计算机上进行。     

导线网的精度分析

本文按条件平差原理通过机助法对5类34种典型图形进行模拟估算,经过分析比较,得出布设导线网时的一些结论及各类导线网最弱点的精度估算公式,供规范修改和设计时参考。     

气候变迁下的古雷电印象浅析

探讨和总结了古雷电研究的4种方法：①地质记录中的古气候标志方法；②氧同位索测量古温度方法；③冰川冰期与气候冷暖方法；④史料记载的研究方法。应用这4种方法分别对史前气候变迁下的古雷电进行描述，然后再从史料记载中，浓缩了古雷电的记录，分析了古雷电印象。     

Assessing desertification

It is widely recognized that desertification is a serious threat to arid and semiarid environments—which cover 40% of the global land surface and are populated by approximately 1 billion humans. Given the potential relevance of this problem, it is surprising that there is no consensus on the proper way to assess the desertification status of a piece of land. During the last 70 years, conflicting definitions have produced both different assessment methodologies and divergent estimates. Contrary to conceptual issues on desertification, assessment methodologies have not been reviewed comprehensively. Here, we critically review the most common methodologies to assess desertification, and describe their principal consequences on scientific and social arenas.We show that desertification assessment has shifted from simple appraisals of the interannual movement of desert boundaries to complex multivariate field surveys, to practical methodologies based on indicators of ecosystem functioning, such as rain use efficiency. Although often regarded as an evidence of stagnation and failure, these methodologies reflect the progress that desertification ecology has experienced. Future challenges for properly assessing desertification are (1) the lack of reference situations against which actual desertification could be compared, and (2) the difficulties that appear when desertification operates through structural rather than functional ecosystem changes.The coexistence of conflicting definitions and divergent estimates negatively affects societal perception, leading to scepticism and, ultimately, to a delay of eventual solutions. Societies must recognize the progress desertification ecology has made, leave behind concepts that no longer represent current knowledge, grasp the opportunity to better assess the extent and intensity of the problem, and, for the time being, realize that assessing desertification is an unsolved issue.     

钻孔灌注断桩事故产生原因及处理措施

简要介绍在钻孔灌注桩施工中发生的断桩事故的原因和处理措施。     

宾川拉乌滑坡形成机理及稳定性评价

拉乌滑坡在不同工况下采用剩余推力法进行了稳定性计算。认为持续降雨或暴雨对滑坡稳定性有很大的影响，提出了滑坡处理措施。     

Historic records of teletsunami in the Indian Ocean and insights from numerical modelling

Following the catastrophic “Great Sumatra–Andaman” earthquake- tsunami in the Indian Ocean on the 26th December 2004, questions have been asked about the frequency and magnitude of tsunami within the region. We present a summary of the previously published lists of Indian Ocean Tsunami (IOT) and the results of a preliminary search of archival materials held at the India Records Office, at the British Library in London. We demonstrate that in some cases, normal tidal movements and floods associated with tropical cyclones have been erroneously listed as tsunami. We summarise archival material for tsunami that occurred in 1945, 1941, 1881, 1819, 1762 and a little known tsunami in 1843. We present the results of modelling of the 2004, 1861 and 1833 tsunami generated by earthquakes off Sumatra and the 1945 Makran earthquake and tsunami, and examine how these results help to explain some of the historical observations. The highly directional component to tsunami propagation illustrated by the numerical models may explain why we are unable to locate archival records of the 1861 and 1833 tsunami at important locations like Rangoon, Kolkata (formally Calcutta) and Chennai (formally Madras), despite reports that these events created large tsunami that inundated western Sumatra. The numerical models identify other areas (particularly the central and southern Indian Ocean islands) where the 1833 tsunami may have had a large enough effect to produce a historic record. We recommend further archival research, coastal geological investigations of tsunami impacts and detailed modelling of tsunami propagation to better understand the record and effects of tsunami in the Indian Ocean and to estimate their likelihood of occurring in the future.     

Rainfall interception in three contrasting lowland rain forest types in Central Kalimantan, Indonesia

Rainfall interception was quantified and modeled for a Lowland Evergreen Rain Forest (LERF) and two Heath Forests (HF) of contrasting stature during a one-year period at a remote site in Central Kalimantan, Indonesia. Throughfall was measured using a roving gauge approach using 18–20 gauges per forest type. Throughfall was 82.8% of incident rainfall in the LERF vs. 89.1% in tall HF and 76.7% in stunted HF. Corresponding stemflow fractions were 0.8%, 1.3% and 2.0% of rainfall, respectively. Interception losses derived for the LERF (16.4%) and the tall HF (9.6%) were close to findings obtained for similar forest types elsewhere but the high interception loss for the stunted HF (21.3%) was unexpected. On the basis of canopy structural characteristics and wet canopy evaporation modeling it is concluded that throughfall in the stunted HF was underestimated and that the specific nature of the HF required a more intensive sampling arrangement. Throughfall sampling schemes in tropical forests, associated errors and hydrological implications are discussed.     

Generating an Image of Dispersive Energy by Frequency Decomposition and Slant Stacking

We present a new algorithm for calculating an image of dispersive energy in the frequency-velocity (f-v) domain. The frequency decomposition is first applied to a shot gather in the offset-time domain to stretch impulsive data into pseudo-vibroseis data or frequency-swept data. Because there is a deterministic relationship between frequency and time in a sweep used in the frequency decomposition, the first step theoretically completes the transform from time to frequency. The slant stacking is then performed on the frequency-swept data to complete the transform from offset to velocity. This simple two-step algorithm generates an image of dispersive energy in the f-v domain. The straightforward transform only uses offset information of data so that this algorithm can be applied to data acquired with arbitrary geophone-acquisition geometry. Examples of synthetic and real-world data demonstrate that this algorithm generates accurate images of dispersive energy of the fundamental as well as higher modes.