地震监测中的电阻率层析技术

将电阻率层析技术应用于地震监测,由视电阻率值重建出介质的真电阻率图像,取得了较好效果.在宝坻台和昌黎台设立的两个试验点上于1998年4月14日ML5.0和ML4.4唐山两次地震前的6天左右层析图像出现了明显的异常变化:宝坻台的电阻率图像一改通常的在平稳背景上叠加小量随机变化的特点,出现了一种有序性特征的新图样;昌黎台也出现了反差加大、高低阻区集中分布的有序性特征.上述异常图样均在震后消失.层析图像在震前出现的熵值降低可能是这次地震活动的前兆.地层导电结构和孔隙度的变化,是引起电阻率异常的直接原因.研究表明,常规的单一极距的视电阻率测量之所以对真电阻率的变化不敏感且丧失空间分辨能力,是由于该物理量同时具有积分值和位函数这两个固有特征所决定的.在地震监测中,改造现行观测系统,引入层析成像,是发展技术的方向.     

岩石破坏前的短临应变前兆研究

采用新型应变仪观测岩样在破坏孕育过程中岩样表面测点的应变变化，结果除了长趋势变化，破坏前几秒的特征变化外，在破坏前百分之几秒至十分之几秒还有突变和拢动等特征变化。     

Atmospheric Corrections Using MODTRAN for TOA and Surface BRDF Characteristics from High Resolution Spectroradiometric/ Angular Measurements from a Helicopter Platform

l. IntroductionThe cIassicaI definition of bi--directional reflectance--distribution function (BRDF) is aderivative, distribution function, relatlng the irradiance incident from one given direction tolts contribution to the radiance renected in another direct1on (N1codemus et al., l977).f r (0,, rp,; 0,, rp, )= dL, (0,, P,; 0,, 9,; E, )/ dE, (0,, 9,) [sr-- 1 ], (l)where 0 (zenith angle) and 9 (azimuth angle) together indicate a direction, the subscr1pt i indi-cates quantities associated wi…     

The focal mechanism solution of the Ms6.5 Wuding earthquake in Yunnan Province of October 24,1995

ＴｈｅｆｏｃａｌｍｅｃｈａｎｉｓｍｓｏｌｕｔｉｏｎｏｆｔｈｅＭｓ６．５ＷｕｄｉｎｇｅａｒｔｈｑｕａｋｅｉｎＹｕｎｎａｎＰｒｏｖｉｎｃｅｏｆＯｃｔｏｂｅｒ２４，１９９５ＳＨＵＴＩＡＮＭＡ１）（马淑田）ＷＥＩＺＨＡＯ２）（赵薇）１）Ｉｎｓｔｉｔｕｔｅ...     

粘滑过程中声发射序列的时间分布及前兆特征

用声发射波形采集分析系统记录的完整花岗岩在固体围压下破裂及粘滑过程中产生的声发射波形,研究了声发射和粘滑时间序列与天然地震序列的关系,讨论了粘滑过程的时间分布,发现粘滑事件的累积频度曲线随时间的变化受围压和应变率影响,大致呈现指数函数和线性关系两种形式。总事件(包括粘滑和声发射)的累积频度随时间的变化在不同的实验条件下呈现出对数函数形式,粘滑序列中的声发射随时间减少。本文的结果对于研究不同应变速率及不同震源深度的地区的地震活动时间分布特征,以及在判别地震活跃期内不同阶段强震序列类型和前兆特征有一定参考作用。     

ON ICE FORMING NUCLEI

Cloud condensation nuclei(CCN)constitute a reservoir of latent ice-forming nuclei(IFN)active by condensation-followed-by-freezing and by sorption.Two classes of aerosol particles active as IFN by sorption werefound.The first produces IFN concentrations which are dependent on temperature only.The IFN concen-tration consecutively increases with lowering of temperature and does not respond to the increasing partialwater vapor pressure.The second produces IFN concentrations which are dependent on partial water vaporpressure only,The IFN concentration consecutively decreases with decreasing of the partial water vapor pres-sure that takes place with the lowering temperature.Sulfates(mostly ammonium sulfate)constitute an integral part of IFN active by condensation-followed-by-freezing and by sorption.Backward isentropic air parcel trajectories linked polluted air rich in sulfates andclean air with high and low concentrations of IFN active by condensation-followed-by-freezing at-19.7℃ andS_w=0.1%.The experiments were performed in a dynamic filter processing chamber with aerosol particles collectedon membrane filters.     

岩石破裂时电磁辐射的机理研究

本文提出了岩石破裂时的电磁辐射是裂纹尖端电荷随着裂纹加速扩展运动所产生的假说.应用断裂力学方法推导了岩石破裂时初始裂纹长度与裂纹扩展加速度的关系,并计算了其速度和加速度值.根据破裂岩石的电子发射理论,解释了裂纹尖端带电荷的现象.利用岩石在单轴压缩致裂过程中记录到的近场电磁辐射的实验结果,计算了裂纹扩展时裂纹尖端的电荷量和远场电磁辐射强度.通过对电磁辐射波谱分析的研究,得到岩石破裂时电磁辐射频率上限的估计值.最后对岩石破裂时出现的声光电磁现象在理论上作了统一的定性的解释.     

塔里木地台的东部边界问题

本文依据航磁资料，对塔里木地台东部罗布泊地区及其外围的磁场特征，以及基底岩相构造进行了分析，进一步阐述了该区的构造特征。文中根据强磁性基底所反映前寒武纪塔里木中央纬向升高异常带的向东延伸情况，指出塔里木地台向东延伸止于东经91°30′附近，继而为反映褶皱带的弱磁场所取代。据此，文中进一步推测塔里木地台与华北地台自古生代至今可能是不相连的。     

THE ADVERSE IMPACT OF HUMAN ACTIVITIES ON FLOOD CONTROL IN THE HUAIHE BASIN

LIN~DUCnONTheHuaiheBasinislOCatedbetWeen31"-36"llorthemlahtudeand112"-121"easternlongitude,andcoversatotalareaofabout269,000sq.kin,OfwhichthemountainousandhillyareasocCUPyl/3,theplainsandlow-iringland2/3.ThebasinelicitSsalientphysicalgeographicalfeatllTesasfollowsf(l)Thereisnoobviousmountaindividebe~ntheWatershedoftheriVerandtheYellowforerBasinaswellastheYangtZeRadBasin.MostofthetributariesinthenoalbudoftheHuaiheforertakethesouthdikesOftheYellowherasthedivide.(2)TheriVerbedofthetr…