Preliminary Study on Paleoearthquake Chronology on the Northern Liulengshan Piedmont Fault in Yangyuan, Hebei Province, China

The northern Liulengshan piedmont fault is located along the southern margin of the Yangyuan basin and represents a dip-slip normal fault,generally NEE-trending and NNW-dipping.Landforms offset by the fault are fairly developed and well preserved in the Dushanpu area of Yangyuan County,Hebei Province.Two trenches were excavated in front of a scarp of the northern Liulengshan piedmont fault at Dushanpu and two paleoseismic events were revealed in the trenches,from which several samples were collected for dating.The samples were dated using the IRSL dating technique.The preliminary result shows the possible ages of the two paleoseismic events.     

Pattern of latest tectonic motion and its dynamics for active blocks in Sichuan-Yunnan region,China

Based on the concept of “active blocks” and spatial distribution of historical earthquakes with surface ruptures as well as major and subordinate active faults. The Sichuan-Yunnan region can be divided into four first-order blocks. They are the Markam block (I), the Sichuan-Yunnan rhombic block (II), Baoshan-Pu’er block (III), and Mizhina-Ximeng block (IV). Cut by sub-ordinate NE-trending active faults, the Sichuan-Yunnan rhombic block (II) can be further divided into two sub-blocks: the northwestern Sichuan sub-block (ll₁) and the middle Yunnan sub-block (ll₂), while the Baoshan- Pu’er block (III) can be further divided into three sub-blocks: Baoshan sub-block (Ill₁), Jinggu sub-block (lll₂), and Mengla sub-block (lll₃). A quantitative study of offset landforms is carried out and the basic types of active faults and their long-term slip rates along the major boundaries of active blocks of different orders in the Sichuan-Yunnan region are determined, through slip vector analysis, the motion states of the active blocks are clarified and the deformation coordination on the block margins is discussed. It is suggested that the tectonic motion of the blocks in this region is a complex or superimposition of three basic types of motions: southeastward sliding, ro-tating on vertical axis, and uplifting. The Markam block (I), the northwestern Sichuan sub-block (ll₁), and middle Yunnan sub-block (ll₂) have a southeastward horizontal sliding rate of 1-5 mm/a, clockwise rotating angular rate of 1.4-4°/Ma, and uplifting rate of about 1 mm/a. The Baoshan-Pu’er (III) and Mizhina-Ximeng (IV) blocks have also been extensively clockwise rotated. This pattern of motion is a strain response to the collision between the Indian and Eurasian plates and the localized deformation and differential slip on the block margins associated with the northward motion of the Indian Plate. Because a set of transverse thrusts between the blocks absorbs and transforms some components of eastward or southeastward sliding motion, the eastward escape or extrusion of the Tibetan Plateau is limited as “imbricated thrusting transformation-limited extrusion model”.

     

全球地理信息资源建设项目质量监督检查

充分总结分析全球地理信息资源建设项目质量管理、项目生产、质量监督等工作实际的情况下,针对前期准备、资料收集利用、生产过程、验前成果等关键环节,研究影响成果质量的监督措施,消除质量隐患。严格控制产品质量及精度指标,保障数据处理与产品制作的科学性、准确性及完整性,全面、真实、准确反映出地理空间信息,为我国参与全球治理和履行大国责任提供有效的地理信息资源支撑。     

活动断层探察数据的信息编码优化研究

从20世纪90年代起,研究人员就开始探索活动断层探察数据的制作、存储与管理。迄今为止,已经获得了大量的活动断层探察数据,建成了一套系统的数据组织体系,为减轻地震灾害的相关研究提供了数据和技术支撑。近年来,随着活动断层数据库信息的扩充,初期设计的部分属性信息编码已不适用。为了形成适应当前工作的属性信息编码体系,本文以活动断层数据库建设体系为基础,对数据库属性值代码进行信息分类和编码优化。文章将数据库属性值代码分为字符型单一含义值、数值型单一含义值及复合含义值,分别进行编码规则设计,最终优化了数据库属性信息编码体系,提高了从建库到数据应用的数据录入、检测、制图自动化、数据分析等环节的效率。     

Newly-generated Seismic Rupture Zone:Identification,Type Division and Seismogeological Significance

The results of geological research show that those phenomena such as surface geology,geomorphology,deep geophysical field,and time-space distribution of seismicities can be usedas the main seismogeological indicators to identify the newly-generated seismic rupture zone(NSRZ).According to their formation and evolution process,the NSRZs can be divided intothree types:pre-rupture-isolated,quasi-rupture-discontinuous and major-rupture-connected.In a pre-rupture-isolated NSRZ,the seismicity is dominated by medium-small earthquakes.In a quasi-rupture-discontinuous NSRZ,the frequency and intensity of strong earthquakesincrease and there may even be the largest earthquake to occur.A major-rupture-connectedNSRZ is the segment where rupture has entered the mature stage;in such a zone,theintensity and duration of seismic activity depend on the constitutive condition and regionalstress field in the zone.     

Relocation and Genetic Analysis of Earthquakes in the West of Xietan Area of Three Gorges Reservoir

136 earthquakes,taking place in the west of Xietan area,recorded by portable stations deployed in the Three Georges reservoir area were relocated using the double difference algorithm.The relocations show that the root-mean-square deviations of the relocations in the directions of E-W,N-S and U-D are 0.38km,0.33km and 0.98km,respectively.The earthquakes in clasolite area with focal depths of about 4km～5km take on linear distributions from the shallow to deep parts.These earthquakes were deduced to be reservoir-induced earthquakes of fault fracture type.In contrast,the earthquakes in limestone pavement with the focal depths about 2km～3km take on slightly divergent distributions and have the characteristics of reservoir-induced earthquakes of the karst collapse type.     

基于历史地震数据的地震烈度与人员死亡率相关性研究

基于历史震例数据,通过对不同烈度的人员死亡率的分析发现,人员死亡率与地震烈度存在着正相关关系,即人员死亡率随烈度的增加而增大,不同烈度的人员死亡率有各自的分布区间范围,而通过对相邻烈度的人员死亡率的分析发现,相邻烈度人员死亡率存在着1个数量级的倍数关系,一般在10倍左右,在低烈度区域,倍数关系集中于偏向大于10倍的区间范围;在高烈度区域,倍数关系集中于小于10倍的区间范围。在此结果上,基于地震烈度、震级等因素构建了烈度人员死亡率模型,决定系数R²值为0.8667,拟合结果相对较好,能够为后续基于分烈度人员死亡率的地震人员死亡评估模型提供参考。     

Spatiotemporal characteristics of earthquake disaster losses in China from 1993 to 2016

The present study analyzes the runoff response during extreme rain events over the basin of Subarnarekha River in India using soil and water assessment tool (SWAT). The SWAT model is configured for the Subarnarekha River basin with 32 sub-basins. Three gauging stations in the basin (viz., Adityapur, Jamshedpur and Ghatshila) were selected to assess the model performance. Daily stream flow data are taken from Central Water Commission, India—Water Resources Information System. Calibration and validation of the model were performed using the soil and water assessment tool-calibration uncertainty programs (SWAT-CUPs) with sequential uncertainty fitting (SUFI-2) algorithm. The model was run for the period from 1982 to 2011 with a calibration period from 1982 to 1997 and a validation period from 1998 to 2011. The sensitivity of basin parameters has been analyzed in order to improve the runoff simulation efficiency of the model. The study concluded that the model performed well in Ghatshila gauging station with a Nash–Sutcliffe efficiency (NSE) of 0.68 during calibration and 0.62 during validation at daily scale. The model, thus calibrated and validated, was then applied to evaluate the extreme monsoon rain events in recent years. Five extreme events were identified in Jamshedpur and Ghatshila sub-basins of Subarnarekha River basin. The simulation results were found to be good for the extreme events with the NSE of 0.89 at Jamshedpur and 0.96 at Ghatshila gauging stations. The findings of this study can be useful in runoff simulation and flood forecasting for extreme rainfall events in Subarnarekha River basin.     

Application of a novel laser sensor volume measurement system to the triaxial testing of an unsaturated lime-treated soil

The paper reviews the common techniques of volume change measurement during unsaturated soil testing, focusing in particular on a newly developed system by the authors. The advantages and accuracy of the system compared to other available volume measurement techniques are discussed. This is followed by the application of the system to the volume change measurement of a lime-treated clay soil during suction-controlled triaxial testing, and a discussion on the behaviour of the soil during shearing.     

2008年汶川地震滑坡详细编目及其空间分布规律分析

最新研究成果表明, 2008年5月12日汶川MS 8.0级地震触发了超过197000处滑坡。首先,基于GIS与遥感技术构建了汶川地震滑坡的3类编目图,分别为单体滑坡面分布数据、滑坡中心点位置和滑坡后壁点位置。构建方法为基于地震前后高分辨率遥感影像的目视解译方法,区分单体滑坡并圈定其边界,对滑坡后壁进行识别与定点,并开展了部分滑坡的野外验证工作。这些滑坡分布在一个面积大约为110000km2的区域内,滑坡总面积约为1160km2。选择一个面积约为44031km2的区域作为研究区,区内滑坡数量为196007个,滑坡面积为1150.622km2,这是最详细完整的汶川地震滑坡编录成果,也是单次地震事件触发滑坡最多的记录。其次,开展研究区内的地震滑坡空间分布规律的研究。基于滑坡面与滑坡中心点分别构建滑坡空间分布面积密度图与点密度图,结果表明:滑坡多沿着映秀北川断裂分布,多发生在断裂的上盘。滑坡的高密度区位于映秀北川同震地表破裂的南西段(映秀镇与北川县之间)的上盘区域,这一区域恰对应着逆冲分量为主的断裂上盘,表明逆冲断裂对上盘区域发生滑坡的极强烈的控制作用,而该区域正是形变最大的区域,因此说明是地震滑坡发生的强烈控制作用。基于滑坡面密度(LAP)、滑坡中心点密度(LCND)与滑坡后壁点密度(LTND)这3个衡量指标,使用统计分析方法,评价了汶川地震滑坡与地震参数、地质参数、地形参数的关系。结果表明:LAP、LCND与LTND这3个衡量指标与坡度、地震烈度与PGA存在明显的正相关关系; 与距离震中、距离映秀北川同震地表破裂存在负相关关系; 斜坡曲率越接近0,滑坡越不易发生; LAP、LCND与LTND的高值高程区间为1200～3000m; 滑坡发生的优势坡向为E、SE、S方向; 滑坡发育的易发岩性为砂岩与粉砂岩(Z)、花岗岩; 滑坡与坡位的相关关系不太明显。统计结果还表明LCND与LTND两个衡量指标的差异对地震与地质因子不敏感,而对地形因子较敏感。最后将本文的统计结果与以往的汶川地震滑坡空间分布规律统计成果进行了一些对比,对比结果表明,对于某些因子,如高程、岩性、距离震中、距离映秀北川断裂的统计分析结果,采用不完整的滑坡分布数据或点数据,与采用较完整的滑坡分布面数据会有一定的差异,这种差异并未出现在针对坡度与坡向等因子的统计对比结果中。总之,作者认为一个完备、详细的地震滑坡分布面要素编目图是地震滑坡空间分布规律定量分析、危险性定量分析与滑坡控制的地震区地貌演化研究的重要基础,否则,与实际情况相比,得到统计结果会有一定的偏差,本文的研究成果与以往成果的对比结果证明了这一点。