跨断层测量不等间隔计算的数据匹配

跨断层测量的数据处理中,常利用不等间隔数据进行计算,由此产生一系列问题,如时间计算、同步性、主从关系、可比性等。对此,从合理、最佳的要求出发,以约定的方式进行设计,考察它们在多种算法中的适应能力,有利于跨断层测量数据处理的完善和发展。
     

RUPTURE CHARACTERISTICS OF LATE QUATERNARY STRONG EARTHQUAKES ON THE WESTERN BRANCH OF THE XIAOJIANG FAULT ZONE

The Xiaojiang fault zone is located in the southeastern margin of the Tibetan plateau, the boundary faults of Sichuan-Yunnan block and South China block. The largest historical earthquake in Yunnan Province, with magnitude 8 occurred on the western branch of the Xiaojiang Fault in Songming County, 1833. Research on the Late Quaternary surface deformation and strong earthquake rupture behavior on the Xiaojiang Fault is crucial to understand the future seismic risk of the fault zone and the Sichuan-Yunnan region, even crucial for the study of tectonic evolution of the southeastern margin of Tibetan plateau. We have some new understanding through several large trenches excavated on the western branch of the Xiaojiang fault zone. We excavated a large trench at Caohaizi and identified six paleoseismic events, named U through Z from the oldest to the youngest. Ages of these six events are constrained at 40000-36300BC, 35400-24800BC, 9500BC-500AD, 390-720AD, 1120-1620AD and 1750AD-present. The Ganhaizi trench revealed three paleoearthquakes, named GHZ-E1 to GHZ-E3 from the oldest to the youngest. Ages of the three events are constrained at 3300BC-400AD, 770-1120AD, 1460AD-present. The Dafendi trench revealed three paleoearthquakes, named E1 to E3 from the oldest to the youngest, and their ages are constrained at 22300-19600BC, 18820-18400BC, and 18250-present. Caohaizi and Ganhaizi trenches are excavated on the western branch of the Xiaojiang Fault, the distance between them is 400m. We constrained four late Holocene paleoearthquakes with progressive constraining method, which are respectively at 500-720AD, 770-1120AD, AD 1460-1620 and 1833AD, with an average recurrence interval of 370~440a. Large earthquake recurrence in the late Holocene is less than the recurrence interval of~900a as proposed in the previous studies. Thus, the seismic hazard on the Xiaojiang Fault should be reevaluated. We excavated a large trench at Dafendi, about 30km away south of Caohaizi trench. Combining with previous paleoseismological research, it is found that the western branch of Xiaojiang Fault was likely to be dominated by segmented rupturing in the period from late of Late Pleistocene to early and middle Holocene, while it was characterized by large earthquakes clustering and whole segment rupturing since late Holocene.     

ANALYSIS OF THE CONFIDENCE INTERVAL OF THE COMPOSITE FAULT PLANE SOLUTION OBTAINED FROM THE GRID SEARCH METHOD: AN EXAMPLE OF SOUTHERN JIANGXI PROVINCE

In order to quantitatively analyze the reliability of the composite fault plane solution of small earthquakes, the Bootstrap sampling technique is introduced into the grid search method, and the ideas and methods for calculating the confidence interval from the grid search method are proposed initially. There are two sample sets that can represent the characteristics of the composite fault plane solution. One sample set is the optional solutions obtained by the grid search method and the other is obtained by the Bootstrap sampling technique. Then, we calculate the confidence intervals of the two sample sets (P, B and T axis). The research results of tectonic stress field in southern Jiangxi Province are relatively few. In view of such situation, we use the focal mechanism solutions of small earthquakes to calculate and analyze the composite fault plane solution and the confidence interval. This study shows that the confidence interval of the principal stress axis can be obtained well by both of the sample methods. The reliability of the results and the confidence range of the principal stress axis can be better represented by the confidence intervals. The middle principal stress in southern Jiangxi Province is nearly vertical, and the maximum and minimum principal stresses are nearly horizontal. The direction of maximum principal stress is NWW-SEE and that of the minimum principal stress is NNE-SSW. And, the area is in a strike-slip stress regime. The results are consistent with previous studies, and the stress directions obtained by previous researchers are within the confidence interval calculated by this paper.     

海洋磁力测量测线布设间距的选取

基于海洋磁力测量特点,在对布设测线方向研究的基础上,对海洋磁力测量中布设测线间距的选取进行了研究,提出了选取布设测线间距的原则,给出了几种选取测线间距的方法,并对其可行性进行了验证。     

改进的灰色模型在建筑物沉降预测中的应用

介绍灰色非等间距GM(1,1)模型的建立及其精度评定方法,着重探讨模型精度的主要影响因素,并从模型背景值的构造以及初值选取两个方面对灰色非等间距GM(1,1)模型进行改进,结合高层建筑沉降监测实例进行预测结果分析,结果表明,改进后的灰色模型具有较高的精度,在沉降预测中具有较高的应用价值。     

基于属性数学理论的地图质量评价

首先,通过构造单指标属性测度函数以计算单指标属性测度;其次,以相似数定义相似权的方法,按一种客观性标准确定评价指标的权重值以计算样本综合属性测度;最后,利用置信度准则进行属性识别。研究表明:属性识别模型评判结果与模糊综合评判法和物元分析法的评判结果有较好的一致性,从而验证了属性识别模型应用于地图质量评价的可行性和可靠性。评价指标的权重不会影响属性识别结果,即认为评价指标的权重值相同,因而计算过程大大简化。新的地图质量综合评价与分类方法具有准确度高、易操作的优点。     

基于信息熵的城市边缘区的界定方法研究——以南京市为例

城市边缘区是城乡共同作用的地域单元。如何及时、准确地划分城市边缘区,是目前研究在GIS和RS相关软件的支持下,以南京地区2003年的Landsat TM遥感影像为计算依据,以信息熵理论为基础,结合分析城市边缘区土地利用特征,改进了传统的土地利用信息熵模型,分析熵值分布特点,最后采用突变检测的方法,以熵值60和68确定南京城市边缘区内、外边界的位置,划定了南京城市边缘区的大致范围。研究认为城市边缘区边界是动态变化的;在城乡断面上城市边缘区的景观紊乱度明显高于城市核心区和城市影像区,这为客观划分城市边缘区和利用遥感影像监测城市边缘区的动态变化提供了一个新的途径。     

基于钻孔数据Delaunay-三角网的矿产储量计算

针对传统矿产储量计算的不足,在分析平面点集Delaunay-三角网的算法的基础上,提出基于钻孔点集Delaunay-三角网的算法,并以该三角网为基础,在Visual Basic环境利用组件技术,结合钻孔属性数据库,对任意区域矿产储量进行计算,该法不仅克服算术平均法误差大及其他方法难以自动实现的缺点,而且为管理部门的规划和开采设计提供重要参考信息。     

Geological characteristics and co-exploration and co-production methods of Upper Permian Longtan coal measure gas in Yangmeishu Syncline,Western Guizhou Province,China

Coal measure gas (also known as coal-bearing unconventional gas) is the key field and development direction of unconventional natural gas in recent years. The exploration and evaluation of coal measure gas (coalbed methane, coal shale gas and coal measure tight sandstone gas) from single coalbed methane has greatly expanded the field and space of resource evaluation, which is of positive significance for realizing the comprehensive utilization of coal resources, maximizing the benefits and promoting the innovation of oil and gas geological theory and technological advances in exploration and development. For the first time, in Yangmeishu Syncline of Western Guizhou Province, the public welfare coalbed methane geological survey project of China Geological Survey has been carried out a systematic geological survey of coal measure gas for the Upper Permian Longtan Formation, identified the geological conditions of coal measure gas and found high quality resources. The total geological resource quantity of coalbed methane and coal shale gas is 51.423×10⁹ m³ and the geological resource abundance is up to 566×10⁹ m³/km². In this area, the coal measures are characterized by many layers of minable coal seams, large total thickness, thin to the medium thickness of the single layer, good gas-bearing property of coal seams and coal measure mudstone and sandstone, good reservoir physical property and high-pressure coefficient. According to the principle of combination of high quality and similarity of key parameters of the coal reservoir, the most favorable intervals are No.5⁻², No.7 and No.13⁻² coal seam in Well YMC1. And the pilot tests are carried out on coal seams and roof silty mudstone, such as staged perforation, increasing hydraulic fracturing scale and “three gas” production. The high and stable industrial gas flow with a daily gas output of more than 4000 m³ has been obtained, which has realized the breakthrough in the geological survey of coal measure gas in Southwest China. Based on the above investigation results, the geological characteristics of coal measure gas in the multi-thin-coal-seam-developed area and the co-exploration and co-production methods, such as the optimization method of favorable intervals, the high-efficiency fracturing and reservoir reconstruction method of coal measures, and the “three gas” drainage and production system, are systematically summarized in this paper. It will provide a reference for efficient exploration and development of coal measure gas in similar geological conditions in China.