DISCUSSING THE INFLUENCE OF MAJOR EARTHQUAKE SEQUENCE IN THE LONGMENSHAN AREA ON THE LUSHAN EARTHQUAKE FROM STRESS EVOLUTION          下载免费PDF全文

LIAO Li  LI Ping-en  YANG Jian-si  LIU Pan  FENG Jian-zhou 《地震地质》2018,40(2):450-464

Calculating the coseismic static Coulomb stress change induced by an earthquake and interseismic stress change permits to explain the distribution of aftershocks, the earthquake sequence and other seismic observations. Four earthquakes greater than M7 have occurred in the Longmenshan area before the 2013 Lushan earthquake since 1900. This paper analyzes the influence of these four events on the Lushan earthquake, the stress evolution after the Lushan earthquake accompany with strong earthquake sequence on Longmenshan Fault, and the stress state of the gap between the Lushan and Wenchuan earthquakes. To address these issues would help future seismic risk assessment in the region. We construct a three dimensional finite element model based on the geological structure, the deep inversion results of density and velocity, and the GPS and the stress observation data. The simulation results show that the annual variation rate of Coulomb stress is higher on the Xianshuihe fault and southern segment of the Longmenshan fault, which is consistant with the regional seismicity. The coseismic Coulomb stresses induced by Kangding, Songpan, and Wenchuan earthquakes at the Lushan earthquake epicenter is greater than 0, implying that the three earthquakes may promote the occurrence of the Lushan earthquake, especially the Wenchuan earthquake. The viscous relaxation is remarkable which cannot be ignored in the analysis of stress evolution. From the stress evolution of this area, we can find that the gap between the Wenchuan and Lushan earthquakes is still at a relatively high stress level after the Lushan earthquake.  相似文献   

Linearized amplitude variation with offset and azimuth and anisotropic poroelasticity     

Xinpeng Pan  Guangzhi Zhang  Xingyao Yin 《Geophysical Prospecting》2019,67(7):1882-1897

The normal-to-shear weakness ratio is commonly used as a fracture fluid indicator, but it depends not only on the fluid types but also on the fracture intensity and internal architecture. Amplitude variation with offset and azimuth is commonly used to perform the fluid identification and fracture characterization in fractured porous rocks. We demonstrate a direct inversion approach to utilize the observable azimuthal data to estimate the decoupled fluid (fluid/porosity term) and fracture (normal and shear weaknesses) parameters instead of the calculation of normal-to-shear weakness ratio to help reduce the uncertainties in fracture characterization and fluid identification of a gas-saturated porous medium permeated by a single set of parallel vertical fractures. Based on the anisotropic poroelasticity and perturbation theory, we first derive a linearized amplitude versus offset and azimuth approximation using the scattering function to decouple the fluid indicator and fracture parameters. Incorporating Bayes formula and convolution theory, we propose a feasible direct inversion approach in a Bayesian framework to obtain the direct estimations of model parameters, in which Cauchy and Gaussian distribution are used for the a priori information of model parameters and the likelihood function, respectively. We finally use the non-linear iteratively reweighted least squares to solve the maximum a posteriori solutions of model parameters. The synthetic examples containing a moderate noise demonstrate the feasibility of the proposed approach, and the real data illustrates the stabilities of estimated fluid indicator and dry fracture parameters in gas-saturated fractured porous rocks.  相似文献   

Amplitude variation with incident angle and azimuth inversion for Young's impedance,Poisson's ratio and fracture weaknesses in shale gas reservoirs     

Xinpeng Pan  Guangzhi Zhang 《Geophysical Prospecting》2019,67(7):1898-1911

By analogy with P- and S-wave impedances, the product of Young's modulus and density can be termed as Young's impedance, which indicates the rock lithology and brittleness of unconventional hydrocarbon reservoirs. Poisson's ratio is also an effective indicator of rock brittleness and fluid property of unconventional reservoirs, and fracture weaknesses indicate the fracture properties (fracturing intensity and fracture fillings) in fracture-induced unconventional reservoirs. We aim to simultaneously estimate the Young's impedance, Poisson's ratio and fracture weaknesses from wide-azimuth surface seismic data in a fracture-induced shale gas reservoir, and use the horizontal transversely isotropic model to characterize the fractures. First, the linearized PP-wave reflection coefficient in terms of Young's impedance, Poisson's ratio, density and fracture weaknesses is derived for the case of a weak-contrast interface separating two weakly horizontal transversely isotropic media. In addition, an orthorhombic anisotropic case is also discussed in this paper. Then a Bayesian amplitude variation with incident angle and azimuth scheme with a model constraint is used to stably estimate Young's impedance, Poisson's ratio and fracture weaknesses with only PP-wave azimuthal seismic data. The proposed approach is finally demonstrated on both synthetic and real data sets with reasonable results.  相似文献   

瞬态瑞雷波探测技术及其在矿井地质中的应用   总被引：2，自引：0，他引：2  

潘秋明 《煤田地质与勘探》1996,24(4):53-56

稳态瑞雷波勘探是由高到低逐渐改变振动频率的瑞雷波勘探方法,而瞬志瑞雷波勘探是宽频谱瑞雷波勘探。本文重点介绍了瞬态瑞雷波勘探原理、数字处理技术及其在矿井地质勘探中的应用。   相似文献   

美人蕉(Canna indica)内生细菌促生能力及其强化水体的净化作用     

王晓莹  张明珍  严攀  陈迪松  王亚芬  周巧红  吴振斌  徐栋 《湖泊科学》2019,31(6):1582-1591

从美人蕉(Canna indica)植物体内分离内生细菌.通过测定内生细菌产吲哚乙酸(IAA)、铁载体、固氮、溶磷能力筛选出3株内生细菌C01、C16、C20.本试验的目的为评价接种内生细菌能否促进美人蕉种子萌发和幼苗生长,并通过小型浮床水质净化试验,评价接种内生细菌后的美人蕉对水体中营养物质的去除效果.结果表明:C01、C16、C20促进了美人蕉种子的萌发、生长,C16试验组萌发率为83.3%,显著高于对照组31.1%; C16显著提高了植株的株高和根长,分别比对照组高出23.33%、40.44%.水质净化实验阶段,C16试验组总磷、总氮的去除率分别达到88.4%、96.9%,分别比对照组高出26.4%、15.6%.最终,C01、C16试验组生物量、根长都显著高于对照组.C16试验组植株体内可溶性糖含量、可溶性蛋白显著高于对照组317.3%、97.8%.经鉴定,C01为荧光假单胞菌(Pseudomonas fluorescens),C16为肠杆菌(Enterobacter sp.),C20为欧文氏菌(Erwinia sp.).  相似文献   

西藏麦地卡湿地的浮游植物——2.功能群特征及其与环境因子的关系     

潘成梅  刘洋  安瑞志  巴桑 《湖泊科学》2022,34(4):1115-1126

为揭示青藏高原湿地浮游植物功能群时空分布特征与环境因子的关系,本文于2019年7月(丰水期)和2019年10月(枯水期)在麦地卡湿地调查浮游植物功能群组成和生物量,并运用Spearman相关性分析、冗余分析(RDA)和典范对应分析(CCA)等方法,对麦地卡湿地浮游植物功能群时空分布特征及其与环境因子的关系进行分析.结果表明:1)根据功能群分类方法,麦地卡湿地浮游植物可划分为27个功能群,分别为A、B、C、D、E、F、G、H1、J、K、L_M、L_O、M、MP、N、P、S1、S2、T、T_B、T_C、W1、W2、X1、X2、X3和Z;在时间维度上,丰水期有26个功能群,枯水期有23个功能群;在空间维度上,河流湿地有24个功能群,湖泊湿地有23个功能群,沼泽湿地有12个功能群.2)丰水期,以功能群A、D、L_M、L_O、MP、N、P、T、T_B和X3为主,枯水期以功能群A、D、J、L_M、L_O、MP、N、P、T和T_B为主,其中A和T功能群为2个水情期的共有绝对优势功能群,功能群J仅为枯水期的绝对优势功能群.3)生态状态指数(Q)范围为1.80～4.86,平均值为3.80,表明麦地卡湿地水质状态为“好”.4)相关性分析表明,浊度、COD_Cr、总磷和硝态氮与部分优势功能群生物量具有显著相关性;RDA分析表明,盐度和总氮是影响丰水期优势功能群生物量的主要环境因子.CCA分析表明,总氮和硝态氮是影响枯水期优势功能群生物量的主要环境因子.  相似文献   

太湖沿岸区浅层底泥重金属污染分析及生态风险评价   总被引：2，自引：0，他引：2  

陆志华  蔡梅  王元元  钱旭  潘明祥 《湖泊科学》2022,34(2):455-467

近年来太湖底泥重金属污染越来越受到各方关注.为了解太湖沿岸区底泥重金属污染状况,基于2018年太湖全湖污染底泥勘察项目中重金属监测数据,对梅梁湖、竺山湖、西部沿岸区、南部沿岸区、东太湖、贡湖6个太湖沿岸湖区浅层(0～30 cm深度区间)底泥中Hg、Cd、As、Pb、Cu、Zn、Cr、Ni 8种重金属元素含量进行分析,运...  相似文献   

Substructure hybrid testing of reinforced concrete shear wall structure using a domain overlapping technique     

Yu Zhang  Peng Pan  Runhua Gong  Tao Wang  Weichen Xue 《地震工程与工程振动(英文版)》2017,16(4):761-772

An online hybrid test was carried out on a 40-story 120-m high concrete shear wall structure. The structure was divided into two substructures whereby a physical model of the bottom three stories was tested in the laboratory and the upper 37 stories were simulated numerically using ABAQUS. An overlapping domain method was employed for the bottom three stories to ensure the validity of the boundary conditions of the superstructure. Mixed control was adopted in the test. Displacement control was used to apply the horizontal displacement, while two controlled force actuators were applied to simulate the overturning moment, which is very large and cannot be ignored in the substructure hybrid test of high-rise buildings. A series of tests with earthquake sources of sequentially increasing intensities were carried out. The test results indicate that the proposed hybrid test method is a solution to reproduce the seismic response of high-rise concrete shear wall buildings. The seismic performance of the tested precast high-rise building satisfies the requirements of the Chinese seismic design code.  相似文献   

美国建筑抗震设计的法规体系与设计地震动的确定   总被引：1，自引：1，他引：0  

张萌  潘华  李金臣 《震灾防御技术》2017,12(2):306-318

本文论述了美国建筑抗震设计法规体系发展演变过程及其代表性的规范、标准与技术文档;分析了美国当前建筑法规中设计地震动参数的重要技术见解,设计地震动的不同层次与作用,基于目标风险的最大考虑地震概念等技术的进展,同时,也总结了美国抗震设计相关法规中设计地震动确定的基本规定。本文旨在从美国庞大复杂的建筑设计法规体系中,梳理出清晰的建筑抗震设计的法规体系脉络与设计地震动的要求,为我国建筑抗震设计中设计地震动的相关研究提供参照。  相似文献   

Analysis of the spatial and temporal distributions of ecological variables and the nutrient budget in the Beibu Gulf     

Huanglei Pan  Dishi Liu  Dalin Shi  Shengyun Yang  Weiran Pan 《海洋学报(英文版)》2021,40(8):14-31

Based on a hydrodynamic-ecological model, the temperature, salinity, current, phytoplankton(Chl a),zooplankton, and nutrient(dissolved inorganic nitrogen, DIN, and dissolved inorganic phosphorous, DIP)distributions in the Beibu Gulf were simulated and the nutrient budget of 2015 was quantitatively analyzed. The simulated results show that interface processes and monsoons significantly influence the ecological processes in the gulf. The concentrations of DIN, DIP, phytoplankton and zooplankton are generally higher in the eastern and northern gulf than that in the western and southern gulf. The key regions affected by ecological processes are the Qiongzhou Strait in winter and autumn and the estuaries along the Guangxi coast and the Red River in summer.In most of the studied domains, biochemical processes contribute more to the nutrient budget than do physical processes, and the DIN and DIP increase over the year. Phytoplankton plays an important role in the nutrient budget; phytoplankton photosynthetic uptake is the nutrient sink, phytoplankton dead cellular release is the largest source of DIN, and phytoplankton respiration is the largest source of DIP. The nutrient flux in the connected sections of the Beibu Gulf and open South China Sea(SCS) inflows from the east and outflows to the south. There are 113 709 t of DIN and 5 277 t of DIP imported from the open SCS to the gulf year-around.  相似文献