当前反射地震学研究中的问题浅析

反射地震学作为地震学应用于国民经济建设的分支学科取得了巨大的成功。它在矿产资源勘探、工程建设与环境、自然灾害预测等各种领域发挥了不可替代的作用，特别是在能源开发中功不可殁。另一方面，反射地震学在广泛的工业应用中全面地完善和发展了地震学的理论、方法和技术。时至今日，反射地震学的发展已经从经典理论方法的研究走向更加与客观介质密切相关的深层次研究新阶段，这些问题是，反射地震学从单纯的构造研究走向地层岩性研究，与此有关的是从偏移构造成像步入层析成像、利用单波单分量数据转向应用多波多分量数据、假设地层为固体弹性介质转向双相孔隙介质、各向同性研究转向各向异性研究以及经典的一些方法技术与现代新技术同时使用等。本文对这些方面的研究现状进行概要的分析。     

苍山5.2级地震的地形变特征及机制

运用新方法对苍山地震前后的形变资料进行了异常识别，重点分析形变异常的变化特征及机制。结果显示；（１）苍山地震是大面积应力积累、调整的结果；（２）以外围区１００－２００ｋｍ中短及短期异常为主，而震中１００ｋｍ内的近源区异常并不显著；（３）进入短期的异常标志是中短期异常出现转折或反向。     

1995年苍山5.2级地震前应力场的动态变化

从１９９５年９月２０日山东苍山５．２级地震前源区及其附近不同小区应力场方向的动态变化入手，分析了主应力轴方位、仰角及其矛盾符号比等参量在５．２级地震前的异常变化及其时空演变特点，简析了可能成因，可为研究震前其它各类前兆异常提供背景依据     

太湖水体的总磷分布及湖流对其影响的数值研究

用数值模拟的方法研究了太湖水体中ＴＰ分布特征及湖流对其影响,推导,建立了包括平流,水平扩散,沉降和底泥释放的浅水湖泊中污染物浓度分布计算的二维迎风有限元数值模式,并在给定若干点源条件下计算各种稳态流场下太湖水体中的ＴＰ分布。     

降雨对张家口地震台伸缩仪干扰特征的研究

张家口伸缩仅受降雨干扰，不但与降雨量有关，而且与季节和降雨的方式等也有密切的关系。夏、秋季节持续或突降大雨后，两天左右引起应变量明显的变化，可用2．5倍毫米应变均方差，识别干扰和异常，有较大的使用价值。     

震前自然电场的前兆及其可能机理

研究了震前自然电场的前兆及礤可能机理。主要结论：（１）５．４￣６．２级地震在１５０￣２００ｋｍ,７．０￣７．９级地震在２５０ｋｍ范围内自然电场出现前兆;（２）过滤电场、电化学电场、土体受压变密和机电转换可能是自然电场的前兆机理。     

青海地区地震活动起伏特征之探讨

从地震活动的时间、空间分布探讨青海地区地震活动的起伏特征,认为目前该地区处于地震活动的相对平静时段,未来１～２年以中强地震活动为主。另外从区域垂直形变场、区域应力场的转变,以及青海东部地区地下水趋势性下降等资料进一步论证了这种地震活动起伏现象     

The crystal structure of (Fe<Subscript>4</Subscript>Cr<Subscript>4</Subscript>Ni)<Subscript>9</Subscript>C<Subscript>4</Subscript>

(Fe4Cr4Ni)9C4 is a metal carbide mineral formed by combination of Fe, Cr and Ni with C. It occurs in a chromite deposit in the Luobusha ophiolite, Tibet. Based on the determination of its crystal structure, the empirical formula is (Fe4.12Cr3.84Ni0.96)8.92C3.70 and the simplified formula is (Fe4Cr4Ni)4C9. The mineral is hexagonal with a = 1.38392(2) nm, c = 0.44690(9) nm, pace group P63 m c, Z=6 and the calculated specific gravity Dx = 7.089 g/cm3. Fe, Cr and Ni occupy different crystallographic sites and their coordination numbers are approximately 12, forming an alternate stacking sequence of flat and puckered layers along the c axis. Some metallic atoms have a defect structure. The interatomic distances of Fe, Cr and Ni are 0.2525-0.2666 nm, and the distances between Fe, Cr, Ni and C are 0.1893-0.2169 nm. The coordination number of carbon is 6. It occurs in interstices of the metallic atoms Fe, Cr and Ni to form trigonalprismatically coordinated polyhedra. These coordination polyhedra are linked with each other via shared corners or shared edges into a new type of metal carbide structure.     

基于背景噪声的宁夏及邻区瑞利波层析成像

In this article,the vertical components of the continuous waveform data of 90 seismic stations in Ningxia and its adjacent regions recorded from January 2012 to December 2013 are used to obtain the Rayleigh surface wave group velocity dispersion images in the study area( 101°- 112°E,31°-42°N) according to the method of noise imaging,with period between 6s - 50s and resolution of 0.5°. The Yinchuan basin in the 6s - 26 s period obviously shows a low velocity anomaly,which is not uniform and has a tendency to gradually weaken; the Guanzhong Basin in 6 s-22s shows a strip of low velocity anomaly and demonstrates a transverse inhomogeneity,where velocity in the southeast is slightly faster than that in the northwest. In the 30s - 50s period it shows that in the Yinchuan graben basin and its southern area,there is a large low velocity anomaly area,which moves from northeast to southwest. It shows that between the main active tectonic zones,like mountains and basins,there are obvious geomorphologic boundaries. For example,the deep fault near Liupan Mountain is the dividing line between two large tectonic units of eastern and western of China. The inversion results have good correlation with the geological structure and the stratigraphic landform. The results are consistent with the results of artificial seismic section tomography across the basin. It provides an important basis for the dynamics of active tectonic zones and the mechanism of earthquake occurrence in this area.     

Calculation method of prestack FAGVO and its applications

Frequency attenuation occurs when seismic waves propagate through the porous reservoirs containing hydrocarbons. Current researches on the seismic frequency attenuation mainly focus on the post-stack domain instead of the prestack domain. Here we propose the frequency attenuation gradient vs. offset (FAGVO) based on the amplitude variation with offset and frequency attenuation integral equations. We derive the FAGVO equation that equals to zero in a full-elastic medium and is negative in a viscoelastic medium. FAGVO is affected by the viscosity of the medium, the coefficients of reflection, the frequency variation, and high-frequency attenuation. FAGVO uses the differences of partially stacked data to decrease the interference caused by subsurface strata affecting the frequency attenuation, highlights the frequency attenuation gradient anomalies in hydrocarbon-bearing reservoir pores, and finally realizes the hydrocarbon fluid identification. The method was verified using a two-dimensional wave equation forward model and was found to be cost effective. Furthermore, the method does not require well information, which can be applied in the stage of seismic exploration, especially, in the exploration of a none-well project.