Characteristics of a Short-Term and Imminent Earthquake Precursor Field in the Northern Part of North China and Numerical Simulation of Source Process

According to studies of more than 20 earthquakes with MS≥5.0 in North China, seven features of the short-term and imminent earthquake precursors have been summarized in this paper. At the same time, taking the short-term and imminent earthquake stage as the physical process of a source's medium softening and fault creep, we calculated temporal variation of mean stress, maximum shear stress, body strain, and pore pressure in some certain points (supposed stations) in the source area and its adjacent area by using an anisotropic and nonlinear source model and a finite element method. According to an analysis of these theoretical curves, we conclude that the short-term and imminent earthquake precursors have such characteristics as complex shapes, exponential growth of the precursor number with tune, and precursors' migration from the outside area to the source area, which to a certain extent reveal the cause of the characteristics of the short-term and imminent earthquake precursor field.     

全新世海侵痕迹遥感信息特征提取方法研究*

本文应用TM、MSS、NOAA等多平台、多波段、多时相遥感信息,并结合地貌、水文地质、岩相、历史考古等地学信息进行综合分析,研究华北平原全新世海侵痕迹信息的特征提取方法。研究中特别注重利用与海侵有着直接成因关系的地下咸水体及水化学特征变化所传递的信息。这些信息涉及到水、热、盐、土、植被等环境因子。通过多种图象处理方法,突出古海岸线两侧环境因子的综合差异,识别和勾绘古岸线。     

青藏高原地区地磁场研究

本文根据１９６５．０年代西藏地区地磁测量资料,选用国际地磁参考场模型和区域地磁场矩谐分析方法,对青藏高原地区地磁异常值进行计算和分析,结果表明该区地磁异常场分布的特征与地质构造,尤其是山脉的展布有密切的联系。山脉及近邻地区地磁异常场,不论是梯度,还是绝对值都明显高于相对增坦的地区。     

安徽宣城第四纪红土剖面的全氧化铁含量及其古环境意义

对宣城第四纪红土剖面的研究表明,全氧化铁含量能够较好地指示中国南方第四纪气候的波动。与北方黄土古土壤序列相比,宣城剖面的全氧化铁明显较高,指示了南方地区更强的风化成壤作用。     

Features of Geophysical Fields and Geodynamics of the China Sea

During 1960—1990, an extensive geological-geophysical investigation was carried out in the marine areas of China. According to the materials obtained, the "Geological—Geophysical Serial Maps of the China Seas and the Adjacent Areas (1:2,000,000)" was compiled. In fact, it is a systematic summary of the geological and geophysical work of the China Seas in the past 30 years.In this paper, the author explains the guiding thought and methodology of the compilation of the serial maps, and then briefly discusses the characteristics of geophysical fields and geodynamics, stratigraphy, tectonics and magmatism.     

改进模拟退火法在估计河流水质参数中的应用

将模拟退火法应用于求解分析河流水团示踪试验数据，确定河流水质参数的函数优化问题。针对标准SA算法收敛速度缓慢的弱点，采取了增加附加约束条件、设置内阈值提前降温和增加记忆功能等综合措施对算法进行了改进。算例表明，综合改进措施能够明显地提高算法收敛速度，并可以得到满意的参数计算结果。计算结果也表明，内循环次数不会对外循环次数产生明显的影响。由于算法对目标函数没有附加要求，而且算法的收敛性与待估参数的初值无关，因此，改进SA算法在分析河流水质试验数据、确定水质参数方面．将会具有非常广的应用范围。     

Spatial prediction of landslide susceptibility in western Serbia using hybrid support vector regression (SVR) with GWO,BAT and COA algorithms

In this study, we developed multiple hybrid machine-learning models to address parameter optimization limitations and enhance the spatial prediction of landslide susceptibility models. We created a geographic information system database, and our analysis results were used to prepare a landslide inventory map containing 359 landslide events identified from Google Earth, aerial photographs, and other validated sources. A support vector regression (SVR) machine-learning model was used to divide the landslide inventory into training (70%) and testing (30%) datasets. The landslide susceptibility map was produced using 14 causative factors. We applied the established gray wolf optimization (GWO) algorithm, bat algorithm (BA), and cuckoo optimization algorithm (COA) to fine-tune the parameters of the SVR model to improve its predictive accuracy. The resultant hybrid models, SVR-GWO, SVR-BA, and SVR-COA, were validated in terms of the area under curve (AUC) and root mean square error (RMSE). The AUC values for the SVR-GWO (0.733), SVR-BA (0.724), and SVR-COA (0.738) models indicate their good prediction rates for landslide susceptibility modeling. SVR-COA had the greatest accuracy, with an RMSE of 0.21687, and SVR-BA had the least accuracy, with an RMSE of 0.23046. The three optimized hybrid models outperformed the SVR model (AUC = 0.704, RMSE = 0.26689), confirming the ability of metaheuristic algorithms to improve model performance.     

以盆地资料分析探讨湖南的造山作用

从盆地资料分析得到认识,（１）湖南境内在前中生代有多期由海相向陆相过渡时的造山作用,但造山带主要处于湖南省境外（２）湖南境内中－新生代陆内造山作用强烈,形成了现今所见的若干造山带;（３）中－新生代陆相沉积盆地及控制它们的边界断裂与造山带是统一构造运动或应力条件下的一体化产物。     

钾长石的热释光特征

本文根据不同产状和不同种类的10块钾长石标本的热释光特性分析表明,钾长石的热释光特性不仅取决于矿物晶体的产状和化学成分。而主要还取决于晶体精细结构的特征。钾长石的热释光特性既有差异又存在许多共性,它们存在共同的高温区热释光峰,矿物自身的内辐射场恒定,同时对β辐射的热释光响应敏灵度很高,对阳光的敏感度也很高,这几点共性正是钾长石可以作为热释光断代的基础。     

张文佑教授地学研究五十年

张文佑教授自1934年北京大学地质系毕业开始从事地学研究以来,迄今已整整五十年了。张文佑教授是国内外著名的地质学家和大地构造学家,现任中国科学院主席团成员、中国科学院地学部常委、中国科学院地质研究所所长和国务院学位委员会委员,并兼任中国地质学会和中国石油学会副理事长以及其他多种职务,五十年代早期还曾任中国科学院学术秘书处秘书。