应用浅层地震探测岩溶塌陷的技术研究

本文根据应用浅层地震在唐山探测岩溶塌陷的工作结果,研究了在隐伏岩溶发育区探测岩溶塌陷的技术路线,提出了提高地震勘探效果及地震分辨率的技术措施,分析了对地震时间剖面进行地质解释的技术。     

田间测定沙地水分运动参数初步研究

采用田间垂直入渗试验法测定了沙地水分运动参数，并得到经验拟合曲线。沙土水分特征曲线表明，当体积含水率θ＞５％时，吸力Ｓ随θ增加而缓慢下降，而θ＜５％时，Ｓ随θ的减小而趋于急剧上升。非饱和导水率Ｋ～θ关系表明，当θ＞１５％时，导水率Ｋ值急剧上升，而θ＜１５％时，导水率Ｋ变化缓慢．     

灵台红粘土—黄土—古土壤序列频率磁化率的古气候意义

通过对甘肃灵台晚新生代红粘土－黄土－古土壤序列的磁化率测量和频率磁化率分析，发现红粘土及黄土－古土壤的磁化率和频率磁化率化率存有良好的正相关关系，表明两套沉积在成壤过程中由生物作用或化学作用而形成的超顺磁性矿物含量，对磁化率和频率磁化率增大有重要的贡献。相比化率而言，受影响因素较少的频率磁化率变化，反映了不同气候条件下形成的超顺磁粒级铁磁矿物的相对含量，能更真实、敏感地记录不同时间尺度的古气候波动。灵台红粘土－黄土－古土壤序列的频率磁化等在2．6MaBP前后不同的变率特征，揭示了大冰期来临前后黄土高原的冷暖、干湿反差产生了显著变化，而与此相关的冬、夏季风变迁则表现出不同的组合特征。     

Tracing and dating recent chemical transfers in weathering profiles by trace-element geochemistry and U---U---Th disequilibria: the example of the Kaya lateritic toposequence (Burkina-Faso)

The paper presents a synthesis of the approach recently developed to constrain the nature and the age of recent element mobility in weathering profiles. The approach relies on a comparison of variations of trace elements and U-series disequilibria in weathering profiles. It is exemplified in the case of old lateritic profiles from the Kaya toposequence, Burkina Faso. Trace elements and ²³⁸U---²³⁴U---²³⁰Th disequilibria have been analysed in whole rock samples from two pits located in very contrasted topographical positions. Trace element data show that the whole toposequence is marked by an intense chemical remobilization, including uranium, from the cap to the lower part of the profiles. ²³⁸U---²³⁴U---²³⁰Th disequilibrium data outline that all the levels of the profiles are affected by recent U---Th fractionations, and that each level of the toposequence is marked by U gains and losses. The chronological approach developed in this paper leads to an age of about 400 kyr for the dismantling of the iron cap, and ages ranging from 0 to 400 kyr for U accumulation in the pink clay horizon of the profiles. The depth repartition of U accumulation in the profile implies that the remobilisation processes in this toposequence varied through time, on time constants similar to those of climatic variations. To cite this article: F. Chabaux et al., C. R. Geoscience 335 (2003).     

昌黎台地电阻率近期变化的影响因素研究

通过对昌黎台测区环境变化的调查和电测剖面，井液电阻率等测量结果，分析了该台近十年来电阻率变化发展的过程及其变化原因，结果表明测区附近热矿水的扩散，废污水的渗流和降雨等诸多因素的影响是昌黎台地震阻率多趋势下降变化的主要原因。     

泰国北部梅江断裂探槽剖面研究

通过详细分析上覆于梅江断裂上全新统地层中三个人工探槽剖面，得出该断裂是一条全新世活动断层，且近3000年以来，至少发生过两次7级左右强烈地震事件的结论性认识。     

VELOCITY PROFILES OF TURBULENT OPEN CHANNEL FLOWS

1 INTRODUCTIONThe vertical velocity profile of open channel flows is the most basic infOrmation for the stUdy of flowresistance, channel bed stability, river nuvial process and sediment transport. Although it has been asubject of great interest for many years, there does not exist a consensus on some perPlexing questions,such as the position of the theoretical bed level. In order to investigate the properties of velocity profile,data measured in open channel nows from eight sources were …     

Crustal structure in northern margin of Tianshan mountains and seismotectonics of the 1906 Manas earthquake

Introduction The Tianshan orogenic belt between the Tarim and Junggar basins has re-uplifted in Cenozoic due to the collision and the northwards push-compression of Asia-India plate. The special active tectonic zones have been formed along both south and north margins of the Tianshan mountains (FENG, et al, 1991). The Tianshan seismic belt is one of the major seismic belts in China. A se-ries of strong earthquakes occurred in two flanks of the Tianshan mountains in 20th century, such as …     

Atmospheric surface layer characteristics with MONTBLEX data

Data obtained from the 30m high MONTBLEX tower installed at the Indian Institute of Technology, Kharagpur are described. Data on wind speed and direction, temperature and humidity were recorded during the first week of July 1989 at six levels on the tower. They indicate some of the atmospheric surface layer characteristics. Using two levels of tower data involving wind speed and temperature a profile method was used for computing the surface fluxes of heat and momentum. A method for calculating the surface roughness length using the data was also used to obtain the vertical windspeed profile. The computed wind profile was compared with observations, while the surface roughness length was compared with values obtained by a least square fit. The computed surface fluxes were compared with theoretical values obtained by an energy budget method which uses only wind data at one level. The agreement was reasonably good.     

Numerical simulation of tsunamis — Its present and near future

Hindcasting of a tsunami by numerical simulations is a process of lengthy and complicated deductions, knowing only the final results such as run-up heights and tide records, both of which are possibly biased due to an insufficient number of records and due to hydraulic and mechanical limitation of tide gauges. There are many sources of error. The initial profile, determined with seismic data, can even be different from the actual tsunami profile. The numerical scheme introduces errors. Nonlinearity near and on land requires an appropriate selection of equations. Taking these facts into account, it should be noted that numerical simulations produce satisfactory information for practical use, because the final error is usually within 15% as far as the maximum run-up height is concerned.The state-of-the-art of tsunami numerical simulations is critically summarized from generation to run-up. Problems in the near future are also stated. Fruitful application of computer graphics is suggested.