新疆南天山部分地区尾波衰减特征   总被引：2，自引：0，他引：2  

王筱荣 《内陆地震》1991,5(2):132-137

分析1988年库尔勒和阳霞台地震尾波资料发现,地方震尾波衰减系数α值、尾波持续时间比τ值,在中强震前确有异常显示。  相似文献   

远离绿洲的沙漠近地面观测实验   总被引：10，自引：1，他引：10  

佴抗  胡隐樵 《高原气象》1994,13(3):282-290

通过比较远离经录洲沙漠区与临近绿洲沙漠区近地面的观测资料，发现临近绿洲沙漠区的逆湿现象主要是受到绿洲干扰的影响，沙漠地区地气之间能量交换主要由感热控制，潜热能量可以忽略不计，两个沙漠地区感热通量基本相当。ＨＥＩＦＥ中沙漠或戈壁观测到的能量收支过程基本上能够代表干旱地区的特征。  相似文献   

黑河实验(HEIFE)──对干旱地区陆面过程的一些新认识   总被引：63，自引：2，他引：63  

胡隐樵  高由禧 《气象学报》1994,52(3):285-296

综合介绍“黑河地区地气相互作用野外观测实验研究（ＨＥＩＦＥ）”的概况。系统分析干旱地区陆面过程的一些基本问题，它们是：（１）干旱地区地表面热量平衡的基本特征：干旱地区蒸发量很小，地表热量平衡中以感热为主．潜热可以忽略不计。（２）干旱地区陆面过程参数化问题：干旱地区能量和物质湍流输送的参数化必须考虑层结影响，否则将造成严重误差。（３）干旱地区一种特殊现象──绿洲与沙漠环境的相互作用：绿洲的“冷岛效应”和临近绿洲沙漠或戈壁的“逆湿现象”是这种相互作用的结果。这些研究结果将加深我们对干旱地区陆面过程的认识。  相似文献   

磁层系统的能量输入、输出与日地耦合     

资民筠  沈长寿 《地球物理学报》1994,37(Z2):1-8

用１９７８年和１９８２年３６个磁暴期间的太阳风、行星际磁场（ＩＭＦ）和地磁资料，分析和检验已有的两类太阳风－磁层能量耦合函数．结果表明：Ａｋａｓｏｆｕ提出的耦合函数ε能大致地预报亚暴和磁暴的发生。ε开始起重要作用时即出现亚暴；电离层能耗达到饱和值是发生磁暴的标志。ε与磁层体系能耗之间有接近于对数量的线性关系．用１９７８－１９８６年的资料，分析环电流和极光区电离层能耗在１２１个太阳自转周内的分布表明，日面上可能存在相对持久的活动区域  相似文献   

21世纪能源与环境的前沿问题——天然气水合物   总被引：6，自引：1，他引：6  

孙成权  朱岳年 《地球科学进展》1994,9(6):49-52

天然气水合物资源极为丰富。据国外专家估算，水合物中的天然气总资源超过了包括煤炭、石油与常规天然气在内的所有已知可燃矿产的储量。天然气水合物层是油气聚集的极好盖层，可以作为勘探油气藏的标志。天然气水合物还是影响全球气候变化的重要温室气体之一的甲烷的重要源和汇。因此，进行天然气水合物研究对开拓２１世纪能源、完善油气成藏理论、解决天然气工业生产和输送过程的管进堵塞问题，以及探讨其与全球气候变化的关系问题均有重大意义。目前应开展的研究内容与重点课题包括：天然气水合物的成因机制与油气成藏演化规律；分布规律及有利蕴藏地区；物化特性及其生成与消除的方法；天然气水合物与全球气候变化的关系等。  相似文献   

Multiple scattering of seismic waves in fractured media: Velocity and effective attenuation of the coherent components ofP waves andS waves     

Ian Lerche  David Petroy 《Pure and Applied Geophysics》1986,124(6):975-1019

We show that the multiple scattering by small fractures of seismic waves with wavelengths long compared to the fracture size and fracture spacing is indistinguishable from multiple-scattering effects produced by regular porosity, except for an orientation factor due to fracture alignment. The fractures reduce theP-wave andS-wave velocities and produce an effective attenuation of the coherent component of the seismic waves. The attenuation corresponds to 1000/Q of about unity for a Gaussian spectrum of fractures, and it varies with frequencyf asf ³. For a Kolmogorov spectrum of fractures of spectral index the attenuation is an order of magnitude or so larger and varies with frequency asf ^3-v The precise degree of attenuation depends upon the matrix properties, the fracture porosity, the degree of fracture anisotropy, the type of fluid filling the fractures, and the incidence angle of the wave.For fracture porosities less than about 15% theP-wave andS-wave velocities are decreased by the order of 5–10% with a lesser dependence on the type of fluid filling the fractures (gas, oil, or brine) and with a dependence on both the degree of anisotropy and the incident angle made by the wave. The tendency of fractures to occur perpendicularly to bedding suggests that the best way to measure seismically fractured rock behavior in situ is by using the travel-time delay and reflection amplitude. As both the offset and the azimuth of receivers vary from a shot, the travel-time delay and reflection amplitude should both show an elliptical pattern of behavior—the travel-time delay in response to the varying seismic speed, and the reflection amplitude in response to angular variations in the multiple scattering. Observations of attenuation at several frequencies should permit (a) determination of the spectrum of fractures (Gaussian versus Kolmogorovian) and (b) determination of the contribution of viscous damping to the effective attenuation.  相似文献   

确定沉积岩成岩作用顺序的定量方法     

罗明高 《沉积学报》1995,13(1):88-93

本文从热力学基本定律出发，将复杂的成岩作用过程归结为各种不同的化学反应，从而建立了一套利用反应自由能定量确定成岩作用顺序的方法。该方法将沉积岩成岩作用历史研究从定性引向定量，使其更具理论依据，结果更可靠。利用本方法对国内外两个不同碎屑岩定量研究结果表明，这种方法获得的结果与传统方法的顺序完全一致，从而说明了该方法的良好实用性。  相似文献   

Stress　relaxation　and　attenuation　of　fluid－saturated　sandstone　at　low　frequency   总被引：3，自引：0，他引：3  

席道瑛  刘爱文  刘卫 《地震学报(英文版)》1995,8(4):585-591

Ｓｔｒｅｓｓｒｅｌａｘａｔｉｏｎａｎｄａｔｔｅｎｕａｔｉｏｎｏｆｆｌｕｉｄ－ｓａｔｕｒａｔｅｄｓａｎｄｓｔｏｎｅａｔｌｏｗｆｒｅｑｕｅｎｃｙＤａｏ－ＹｉｎｇＸＩ（席道瑛），Ａｉ－ＷｅｎＬＩＵ（刘爱文）ａｎｄＷｅｉＬＩＵ（刘卫）（Ｕｎｉｖｅｒｓｉｔｙｏ...  相似文献   

Coda waves: A review     

M. Herraiz  A. F. Espinosa 《Pure and Applied Geophysics》1987,125(4):499-577

The analysis and interpretation of coda waves have received increasing attention since the early seventies. In the past few years interest in this subject has spread worldwide, and the study of high-frequency seismic coda waves has become a very important seismological topic. As a conclusion of the studies accomplished in this time, coda waves are considered the result of scattering processes caused by heterogeneities acting on seismic waves.P andS waves play a particularly important role in this interaction. The process introduces an attenuation which, added to the intrinsic absorption, gives the observed apparent attenuation. Therefore, coda waves constitute a thumbprint left by the heterogeneities on the seismograms. Coda waves offer decisive information about the mechanism of how scattering and attenuation take place. This review describes coda waves in detail, and summarizes the work done in this subject to 1986. The relation between coda waves and attenuation in the context of research on seismic scattering problems is stressed. Particular attention has been given to the application of coda waves to estimate source and medium parameters. The state-of-the-art of the temporal variations of coda wave shape, and the possible use of these variations as an earthquake precursor also are presented. Care has been taken to introduce the statistical models used to deal with the heterogeneities responsible for scattering.  相似文献   

中小震近场地震动估计中地震动衰减关系的适用性分析   总被引：9，自引：1，他引：9  

李小军  阎秀杰  潘华 《地震工程与工程振动》2005,25(1):1-7

核工程场地设计基准地震动确定中涉及弥散地震的地震动估计，这导致中小震近场地震动估计成为被关注的研究课题。本文基于一些中小震近场地震动记录资料，分析和探讨了国内外多种地震动衰减关系对中小震近场地震动估计的适用性问题，并结合我国几个核工程地震问题研究工作的实践对中小震近场地震动衰减关系确定的思路和原则提出了建议。  相似文献