Analysis on Depth Distribution and Precursor Mechanism of Small and Moderate Earthquakes

ＩＮＴＲＯＤＵＣＴＩＯＮＲｅｓｅａｒｃｈｏｎｅａｒｔｈｑｕａｋｅｆｏｃｕｓｄｅｐｔｈｄｉｓｔｒｉｂｕｔｉｏｎａｎｄｉｔｓｐｈｙｓｉｃａｌｂａｃｋｇｒｏｕｎｄｉｓｏｎｅｏｆｍｏｓｔａｔ ｔｅｎｔｉｖｅｐｒｏｂｌｅｍｓ.Ｐｒｏｆ.ＦｕＺｈｅｎｇｘｉａｎｇ (1 996)ｒｅｓｅａｒｃｈｅｄｔｈｅｒｅｌａｔｉｏｎｓｂｅｔｗｅｅｎｆｏｃｕｓｄｅｐｔｈｄｉｓｔｒｉｂｕ ｔｉｏｎｏｆａｆｔｅｒｓｈｏｃｋｓ ,ｃｒｕｓｔａｌｖｅｌｏｃｉｔｙｌａｙｅｒｓａｎｄｓｕｒｆａｃｅｔｈｅｒｍａｌｆｌｏｗ .Ｒｅｓｅａｒｃｈｏｎｆｏｃｕ…     

Variation of precipitation in Langtang Valley,Himalayas

The variation of the δ 18O in precipitation and the relationship with precipitation amountat Kyangjin Base House and Yala Glacier Camp in Langtang Valley, Nepal Himalayas were ana-lyzed. The variations of the δ 18O with precipitation had great scatter, and the correlations betweenthe δ18O and precipitation changed with time on the synoptic scale. On the seasonal scale, therewas marked amount effect at Kyangjin Base House. However, the δ18O-precipitation gradient wassmaller than that on the synoptic scale. Because of the maintenance of the basic equilibrium be-tween stable isotopic compositions in atmospheric vapor and precipitation, the evaporation en-richment was light during the rainy season. Therefore, the variation of stable isotopic compositionsin precipitation was independent on the sampling intervals. Simulations show that the rainfall inLangtang Valley was not the outcome of the initial condensation of ocean vapor that originatedfrom low latitudes. The stable isotopic compositions in precipitation were greatly depleted due tothe strong rainout of the vapor from oceans as the vapor was raised over the Himalayas     

VARIABILITY OF AEROSOL OPTICAL PROPERTIES OVER HEFEI DURING SEPTEMBER 1993 TO SEPTEMBER 1994

An 8-wavelength sun-photometer has been operated at Hefei (31.31°N, 117.17°E) to monitoroptical properties of atmospheric aerosols. Altogether 133 solar spectral extinction data were ob-tained on clear days during the period from September 1993 through September 1994, In this pa-per, the feature of the sun-photometer is briefly described. A relative aureole method is intro-duced. which can be used to monitor temporal evolution of aerosol loading during the sun-pho-tometer calibration period. Temporal variabilities of spectral aerosol optical depths and Angstromturbidity parameters are presented. Relation of these variabilities with synoptic and local meteoro-logical conditions are analyzed and discussed, From measured spectral aerosol optical depths undersome representative atmospheric conditions, columnar aerosol size distributions have been retrievedby a linearly constrained inversion method. These typical columnar aerosol size distributions are al-so presented and discussed.     

Improving the computational efficiency of the ambiguity function algorithm

Techniques are described in this paper for improving the Ambiguity Function Method (AFM) for differential GPS positioning using phase observations, (a) that take advantage of optimal dual-frequency observable combinations to improve thereliability of the AFM, and (b) that significantly shorten the computation time necessary for the AFM. The procedure can be used for kinematic positioning applications if a Kalman filter predicted position is accurate enough as an initial position for the suggested AFM searching procedure, or pseudokinematic mode using say a triple-difference solution as an initial position for static positioning if the baseline length is short (typically <5km).     

Preliminary Study on Two Newly-Generated Seismotectonic Zones in North and Southwest China

In previous seismotectonic studies,the emphasis was placed on the inherited active fault zones.In the recent tectonic stage that essentially keeps in step with the current regional geologic environment and the stress field,however,there are also some newly generated fault zones.By studying the seismicity in North and Southwest China,it has been known that the NE-trending Tangshan-Hejian-Cixian and NW-trending Tengchong-Gengma-Lancang seismic zones are just two newly generated fault zones.As distinguished from the inherited fault zones,they are called the newly generated seismotectonic zones.This paper deals with the existence of these two seismogenic zones from their seismicity and geological structures,gives a preliminary analysis of their characteristics,and shows their significance.     

图象恢复在工业CT中的应用

对于以影象增强器为检测系统的目标旋转式工业ＣＴ，分析了其图象退化的因素，采用对一维投影数据进行图象恢复的方法来提高ＣＴ图象质量。文中给出图象恢复公式，从计算机模拟和实验图象恢复的结果可看到所用方法提高了图象清晰度。     

1970年通海7.7级地震人员伤亡研究

本详细阐述了通海地震中人员伤亡的空间分布，对人员伤亡率与房屋倒塌率及地震裂度的关系进行了分析。同时讨论了影响人员伤亡的几种主要因素，给出了人员伤亡率与房屋倒塌率及地震裂的经验关系。认为地震主要伤亡区的分布受发震构造的控制，而建筑类型、地形地貌是影响人员伤的主要因素。     

前汛期北江洪水过程水汽汇与河水流量的关系

本文分析了１９８０－１９８４年４－６月和１９９４年６月洪水过程北江流域的大气水汽汇特征及其与河水流量的关系。结果表明：前汛期洪水过程的前期大乞一般连续存在超过一定值的较强水汽汇，时间为１周左右，洪水的发生是强水汽汇连续产生的径流的积累所致；北江流域洪水期水汽汇的极大峰一般比石角站的洪峰流量超前２天左右，本文结果为洪水的预报提供一条新思路。     

稳定氯同位素在地球科学研究中的进展

本世纪初到八十年代中期由于氯同位素的测试精度很低（＞１．０‰）导致氯同位素地球科学研究未获得任何进展。１９８４年Ｋａｕｆｍａｎｎ等人建立测试精度高达±０．２４‰的方法，并且首次发现了氯同位素在自然界的变异。在此以后氯同位素的测试精度不断提高，各国学者相继对海水、温泉、火山湖水、油田卤水、地下水盐湖、冰雪、环太平洋的斑岩铜矿和美国密西西比型铅锌矿床造岩矿物和造矿矿物流质包裹体中氯同位素进行了测定并对其中氯同位素的分布规律做了比较深入的研究。在此基础上对各类水体及矿床的成因与物质来源进行了有益的探索，另外还以自然界氯同位素产生分馏的原因及机理做了初步的研究。     

钱塘江江心排污的数值模拟

从立面二维非恒定流体动力学方程出发,应用κ-ε湍流模式计算流场,再用准三维的浓度对流-扩散方程,即考虑了侧向扩散的立面二维浓度控制方程,模拟了钱塘江江心6个竖管排污在潮流作用下近区浓度场,其结果和实际观测值基本吻合。