2021年5月云南漾濞Ms 6.4地震序列发震构造及破裂过程初探

北京时间2021年5月21日21时48分36秒,云南省大理州漾濞县发生M_S 6.4地震。利用云南数字地震台网2021年5月18日至8月22日的震相报告,采用双差地震定位法,对漾濞M_S 6.4地震序列进行重新定位。重新定位结果显示序列呈NW向优势分布,破裂长约20 km,宽约7 km,对重新定位结果进行误差分析,水平方向定位误差约为0.8 km,垂直方向定位误差约为1.0 km,定位结果具有较好的稳定性。依据震中分布的走向将序列划分为NW向的主断层与NNW向的分支断层,主断层存在较为明显的分段现象,分支断层呈雁列状分布。根据小震丛集性发生在大震断层面及其附近的原则,利用重新定位后的小震震源位置反演得到漾濞M_S 6.4序列主断层走向约320°,倾角约89°,深度范围3～13 km。根据拟合得到的断层在地表的投影位置,推测本次地震的发震断层为维西-乔后断裂西侧的草坪断裂。基于断层滑动量分布识别出3个凹凸体,结合序列时空演化特征,分析了漾濞M_S 6.4地震序列的破裂过程,结果显示断层中段的凹凸体发生初始破裂...     

Multiple evidences indicate no relationship between prehistoric disasters in Lajia site and outburst flood in upper Yellow River valley,China

All around the world, ancient legends exist about the Great Flood, and the influence of the Great Flood in human evolutionary history is a hotly debated topic. In China, the legend of the prehistoric Great Flood and Yu the Great’s flood control has a long history and is considered to be closely linked to the establishment of the Xia Dynasty. However, there is a lack of solid scientific evidence. Against this issue, some scholars have proposed that an earthquake around 1920 BCE in the Guanting Basin along the upper reaches of the Yellow River led to the creation of a lake by damming in the Jishi Gorge and that the outburst of water from that lake led to the massive flood in the Yellow River region. These studies provided new scientific evidence for the Chinese legend. In this paper, we date skeletal samples embedded in earthquake sand blasting from the Lajia site, analyze remains from natural disasters (such as earthquakes and floods) and also archaeological remains. In addition, we compared the skeletal samples dating with that of sediments from the dammed-up lake. Our results are inconsistent with those of previous scholars. The earthquake at the Lajia site occurred no earlier than 1800 BCE, and the dammed-up lake in Jishi Gorge had disappeared by 3600 BCE. Thus, the formation and outburst of the dammed lake, the sudden death of ancient humans at the Lajia site and the ancient earthquake were independent events occurring at different times. In addition, the massive flood in the upper reaches of the Yellow River did not actually happen. Thus, we argue against and invalidate the hypothesis that the massive flood was related to Yu the Great’s flood control and the establishment of the Xia Dynasty.     

Traffic Assignment Forecast Model Research in ITS

As an important role in the development of ITS, traffic assignment forecast is always the research focus. Based on the analysis of classic traffic assignment forecast models, an improved traffic assignment forecast model, multi-ways probability and capacity constraint (MPCC) is presented. Using the new traffic as- signment forecast model to forecast the traffic volume will improve the rationality and veracity of traffic as- signment forecast.     

A comparison of the effectiveness of the roots of two grass species in reducing soil erosion on alluvial fans in south-east China

The effects of root systems on soil detachment by overland flow are closely related to vegetation types. The objective of this study was to quantify the effects of two gramineous roots (Paspalum mandiocanum with shallow roots and Pennisetum giganteum with deep roots) on soil detachment capacity, rill erodibility, and critical shear stress on alluvial fans of benggang in south-east China. A 4-m-long and 0.12-m-wide flume was used. Slope steepness ranged from 9% to 27%, and unit flow discharge ranged from 1.39 × 10⁻³ to 4.19 × 10⁻³ m² s⁻¹. The mean detachment capacities of P. mandiocanum and P. giganteum lands were 18% and 38% lower than that of bare land, respectively, and the effects of root on reducing soil detachment were mainly reflected in the 0- to 5-cm soil layer. The most important factors in characterizing soil detachment capacity were root length density and soil cohesion, and soil detachment capacity of the two grass lands could be estimated using flow shear stress, soil cohesion, and root length density (NSE = 0.90). With the increase in soil depth, rill erodibility increased, whereas shear stress decreased. The mean rill erodibilities of P. mandiocanum and P. giganteum lands were 81% and 61% as much as that of bare land, respectively. Additionally, rill erodibilities of the two grass lands could be estimated as an exponential function by root length density and soil cohesion (NSE = 0.88). The mean critical shear stress of P. mandiocanum and P. giganteum lands was 1.29 and 1.39 times that of bare land, respectively, and it could be estimated with a linear function by root length density (NSE = 0.76). This study demonstrated that planting of the two grasses P. mandiocanum and P. giganteum could effectively reduce soil detachment and enhance soil resistance to erosion on alluvial fans, with the deep roots of P. giganteum being more effective than the shallow roots of P. mandiocanum. The results are helpful for understanding the influencing mechanism of root systems on soil detachment process.     

藉由InSAR资料分析汶川地震:震前及震后地表变形(英文)

Capability of mapping surface deformation offered by satellite radar interferometry has been successfully demonstrated and applied since early 90s, from short to long terms measuring and tracing of deformation patterns up to centimeter scale, both qualitatively and quantitatively.     

南京降水氢氧同位素监测特征

基于2018年7月—2019年6月南京降水同位素观测数据和中国气象局气象观测数据,研究南京降水稳定同位素组成的变化特征,对比热带气旋降水、梅雨降水和其他降水的降水同位素组成特征,研究降水同位素组成与热带气旋移动路径关系。结果表明：南京降水氧同位素组成(δ18O)和氢同位素组成(δ2H)的变化范围分别为-16.3‰~4.0‰和-103.0‰~32.9‰,雨季降水氢氧同位素组成相对贫化,非雨季相对富集;降水氘盈余的降水加权平均值为15.5‰,表明南京降水受陆面过程影响大。从降水量权重看,热带气旋降水和梅雨降水强度大,降水氢氧同位素组成严重贫化;其他降水的强度相对较弱,降水氢氧同位素组成比较富集;受水汽源地和陆面循环等过程的综合影响,热带气旋降水氘盈余小于全球平均值(10‰),梅雨降水氘盈余略高于全球平均值,其他降水氘盈余远高于全球平均值。登陆前仅在海洋上移动的热带气旋,降水氘盈余维持在7.5‰~8.6‰,但二次登陆的热带气旋降水氘盈余远大于10‰,可能是受到陆地蒸散过程的影响。     

城市大气气溶胶的物理化学特性及其对人体健康的影响

根据在北京、重庆、上海等城市大气气溶胶的观测结果和气溶胶中有机化学成分的有关资料,分析城市地区大气气溶胶的浓度、尺度谱分布、日变化规律及其化学成分的谱分布特征,并与干净地区的结果作比较,进而探讨了大气气溶胶对人体健康的影响。     

A preliminary research on the climatic records of lacustrine deposits of Qingtu Lake in the last 6000 years

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Influencing factors for formation of urban and rural spatial structure in metropolis fringe area—Taking Shuangliu County of Chengdu in China as a case

With rapid urbanization process, the pace of urban sprawl has been quickened and most metropolises have experienced expansions in leaps and bounds in suburbanization, which has greatly changed the urban and rural spatial structure of the metropolis fringe area. In this paper, Shuangliu County is taken as a case, since it is a typical fringe area of Chengdu Metropolis. Based on Landsat TM images of Chengdu City and Shuangliu County obtained in 1985, 2000 and 2004, characteristics of urban and rural spatial structure in Shuangliu County were analyzed, such as core-periphery spatial structure and some obvious integration trends. Then the influencing factors for the formation of urban and rural spatial structure were identified, including some natural, social, economic and political factors. According to the discussion of this paper, Shuangliu County is undergoing a key transition and reform period. Its formation of urban and rural spatial structure was affected not only by such common factors as the location, natural background, industrial transition, migration, etc., but also by some unique factors such as city planning and policy guidance, which played an important role in accelerating its uneven spatial structure. The understanding of the role of the influencing factors would be useful for carrying out spatial management and development planning of metropolis fringe area.     

A new approach to measurement of regional inequality in particular directions

Regional inequality is a core issue in geography,and it can be measured by several approaches and indexes.However,the global inequality measures can not reflect regional characteristics in terms of spatiality and non-mobility,as well as correctly explore regional inequality in particular directions.Although conventional between-group inequality indexes can measure the inequality in particular directions,they can not reflect the reversals of regional patterns and changes of within-group patterns.Therefore,we set forth a new approach to measure regional inequality in particular directions,which is applicable to geographic field.Based on grouping,we established a new index to measure regional inequality in particular directions named Particular Direction Inequality index(PDI index),which is comprised of between-group inequality of all data and between-group average gap.It can reflect regional spatiality and non-mobility,judge the main direction of regional inequality,and capture the changes and reversals of regional patterns.We used the PDI index to measure the changes of regional inequality from 1952 to 2009 in China.The results show that:1) the main direction of China’s regional inequality was between coastal areas and inland areas;the increasing extent of inequality between coastal areas and inland areas was higher than the global inequality;2) the PDI index can measure the between-region average gap,and is more sensitive to evolution of within-region patterns;3) the inequality between the northern China and the southern China has been decreasing from 1952 to 2009 and was reversed in 1994 and 1995.