Rupture process of the M_s 7.0 Lushan earthquake, 2013     

LIU ChengLi  ZHENG Yong  GE Can  XIONG Xiong  HSU HouTze 《中国科学:地球科学(英文版)》2013,(7):1187-1192

On April 20, 2013 at 8:02 am, a magnitude 7.0 earthquake occurred in Lushan County, Sichuan Province, China, which induces massive landslides, causes great losses to life and property. Based on the locations of aftershocks provided by the China Earthquake Network Center and the characteristic of Longmenshan active faults system, combined with the current preliminary focal mechanism solution, the fault rupture direction is determined. With the finite fault inversion method, we invert the rupture process of the Lushan M s 7.0 earthquake by teleseismic waveforms data. The inversion results indicate that the main shock is dominated by thrust fault component and the rupture initiated at depth of 15 km, and most of slip ruptured around the hypocenter with the peak slip of about 1.5 m. Most of rupture slips released at the first 20 s and the main rupture occurred at the first 10 s after the onsets of the mainshock. Most of seismic energy released near the hypocenter with a length of 28 km, especially on both sides of the hypocenter with the range of 20 km, and the seismic energy released relatively smaller in other areas. There is a large area with weak slip between the main rupture and another two asperities on both sides of the hypocenter; it may imply that the accumulated strain on the rupture fault has not been completely released. Therefore, there is a significant possibility of having strong aftershocks in the areas where energy is not fully released. This is also the main reason why there are a lot of moderate to strong aftershocks in the Lushan aftershock sequence. In addition, there is an earthquake vacant zone with a length of about 50 km between the Wenchuan M w 7.9 earthquake and this event, which is of high earthquake risk and is deserved to be paid close attention to.  相似文献   

Crustal and upper mantle structure and the deep seismogenic environment in the source regions of the Lushan earthquake and the Wenchuan earthquake   总被引：11，自引：0，他引：11  

ZHENG Yong  GE Can  XIE ZuJun  YANG YingJie  XIONG Xiong  HSU HouTze 《中国科学:地球科学(英文版)》2013,(7):1158-1168

Following the M w 7.9 Wenchuan earthquake, the M w 6.6 Lushan earthquake is another devastating earthquake that struck the Longmenshan Fault Zone (LFZ) and caused severe damages. In this study, we collected continuous broadband ambient noise seismic data and earthquake event data from Chinese provincial digital seismic network, and then utilized ambient noise tomography method and receiver function method to obtain high resolution shear wave velocity structure, crustal thickness, and Poisson ratio in the earthquake source region and its surroundings. Based on the tomography images and the receiver function results, we further analyzed the deep seismogenic environment of the LFZ and its neighborhood. We reveal three main findings: (1) There is big contrast of the shear wave velocities across the LFZ. (2) Both the Lushan earthquake and the Wenchuan earthquake occurred in the regions where crustal shear wave velocity and crustal thickness change dramatically. The rupture faults and the aftershock zones are also concentrated in the areas where the lateral gradients of crustal seismic wave speed and crustal thickness change significantly, and the focal depths of the earthquakes are concentrated in the transitional depths where shear wave velocities change dramatically from laterally uniform to laterally non-uniform. (3) The Wenchuan earthquake and its aftershocks occurred in low Poisson ratio region, while the Lushan earthquake sequences are located in high Poisson ratio zone. We proposed that the effect of the dramatic lateral variation of shear wave velocity, and the gravity potential energy differences caused by the big contrast in the topography and the crustal thickness across the LFZ may constitute the seismogenic environment for the strong earthquakes in the LFZ, and the Poisson ratio difference between the rocks in the south and north segments of the Longmenshan Fault zone may explain the 5 years delay of the occurrence of the Lushan earthquake than the Wenchuan earthquake.  相似文献   

中国南海北部陆坡孔隙度的求取   总被引：4，自引：0，他引：4       下载免费PDF全文

卢良鑫  雷雄  刘学伟 《地球物理学报》2013,56(2):601-607

孔隙度在岩石物理和地震勘探领域都是一个非常重要的参数,水饱和地层的孔隙度可以用于求海底地层的弹性模量进而求取纵横波速度、识别水合物以及估计水合物的储量等.然而在没有打钻的情况下要相对准确地了解海底未固结成岩地层的孔隙度变化趋势是困难的.历史上有学者提出了几个模型,都是基于孔隙度随深度的增加呈现指数下降的趋势,并且需要知道指数模型中的若干参数,因此就产生了两个问题,一是孔隙度是否随深度增加而呈现指数下降,二是指数模型中参数如何选取.本文从另外一个角度,即利用海底介质的压实性从表层开始往下逐层求取水饱和地层的孔隙度,此方法被称之为"体积模量法",它仅需要知道表层孔隙度和地层矿物组分,从而节省了勘探成本.本文将该方法应用于我国南海地区和美国ODP井数据,结果与测井数据以及地震反演数据吻合得较好.  相似文献   

Strategies for real-time spatial analysis using massively parallel SIMD computers: an application to urban traffic flow analysis     

Demin Xiong  Duane F. Marble 《International journal of geographical information science》2013,27(6):769-789

Abstract

The current research focuses upon the development of a methodology for undertaking real-time spatial analysis in a supercomputing environment, specifically using massively parallel SIMD computers. Several approaches that can be used to explore the parallelization characteristics of spatial problems are introduced. Within the focus of a methodology directed toward spatial data parallelism, strategies based on both location-based data decomposition and object-based data decomposition are proposed and a programming logic for spatial operations at local, neighborhood and global levels is also recommended. An empirical study of real-time traffic flow analysis shows the utility of the suggested approach for a complex, spatial analysis situation. The empirical example demonstrates that the proposed methodology, especially when combined with appropriate programming strategies, is preferable in situations where critical, real-time, spatial analysis computations are required. The implementation of this example in a parallel environment also points out some interesting theoretical questions with respect to the theoretical basis underlying the analysis of large networks.  相似文献   

天文成像数值仿真的相位屏模拟方法     

常翔  李荣旺  熊耀恒 《云南天文台台刊》2012,(1):46-55

通过利用Monte—Carlo方法对湍流相位屏模拟进行验证和分析。给出加入次谐低频补偿相位屏与直接谱反演相位屏的对比结果,并分析了在考虑内外尺度时次谐低频补偿方法的有效性。此外,给出了基于天文观测的多相位屏的湍流分层模型。在此基础上对天文成像进行数值仿真,并给出了仿真结果。  相似文献   

Characterization and constitutive modeling of red clay contaminated with ammonium carbonate     

Shanmei Li  Beshoy Riad  Xiong Zhang  Zhikui Liu 《国际地质力学数值与分析法杂志》2020,44(17):2329-2357

Conventionally, red clay is used for agricultural purposes in southern China. Fertilizers, especially urea, are commonly introduced into the red clay to improve the crop yields. However, due to the rapid urbanization in China, large areas of lands with red clays have been converted into sites for domestic and industrial constructions. Nevertheless, few researchers focused on the effect of urea on the strength and compressibility of red clay. In this research, the shear strength and compressibility of the red clay saturated by different concentrations of the (NH₄)₂CO₃ solution (urea's hydrolysates) were experimentally investigated using direct shear as well as oedometer tests, respectively. It was noticed that both the shear strength and stiffness of the red clay significantly decreased after exposure to the urea solution. In addition, the micromechanisms of the strength and compressibility of the red clay treated by the (NH₄)₂CO₃ were studied by the scanning electron microscope test and X-ray diffraction test. Based on the test results, a new model was developed to simulate the chemomechanical behavior of saturated clayey soil by modifying the Barcelona basic model (BBM) for unsaturated soils. The proposed model introduces four additional parameters, compared to the BBM, to account for the nonlinear shear strength behavior of the red clay. This model accounts for most of the complex features related to the strength and stiffness behavior of clayey soils. The parameter calibration procedures, by using the oedometer and direct shear test results, are also presented. To validate the proposed model, experimental results from the literature are considered in which illite clay samples were either mechanically or chemically or both mechanically and chemically loaded. Part of the experimental results is used to calibrate the model parameters and the other part along with the calibrated parameters is used to verify the proposed model. A comparison between experimental data and predicted results demonstrated that the proposed model is able to capture the main features related to the chemomechanical coupling behavior of saturated soils.  相似文献   

近45年涠洲岛5次珊瑚热白化的海洋站SST指标变化趋势分析   总被引：2，自引：1，他引：1  

汤超莲  李鸣  郑兆勇  周雄  时小军 《热带地理》2010,30(6)

根据涠洲岛珊瑚礁普查(Reef Check)历史资料和涠洲岛海洋站实测海表温度(SST)历史资料,采用对比分析与相关分析方法,分析1966―2010年该岛珊瑚热白化的SST指标变化特征,结果显示:1)涠洲岛珊瑚热白化的最热周平均SST值为31.6℃或最热日平均SST值为32℃;2)1966―2010年涠洲岛的逐年最热月月均SST、最热日日均SST、年极端最高SST及最热周平均SST呈准同步变化,彼此间的相关系数为0.71~0.89,4种珊瑚热白化SST指标没有显著上升趋势;3)最热月月均SST和最热周平均SST的变化趋势与全球变暖在统计上存在显著相关关系。  相似文献   

洞庭湖区湿地恢复的生态补偿效应(英文)   总被引：4，自引：0，他引：4  

熊鹰  王克林 《地理学报(英文版)》2010,20(3):389-405

Eco-compensation is an environmental economic instrument for internalization of external cost.Returning farmland to lake is one of the important parts of restoring wetland ecosystem function in the Yangtze River Valley of China.Whether the project of lake recovery can be successful depends on the compensation to the farmers who have lost their original benefits and contributed to the wetland ecosystem recovery by returning farmland to lake.Aiming at the wetland recovery of the Dongting Lake,the practical im...  相似文献   

GPS高精度重复测量中的天线相位中心偏差检测及改正     

王雄  王建华  胡亚轩  赵永年 《内陆地震》2010,24(1):31-36

首先通过GPS接收机在超短基线上检测数据计算天线相位中心偏差,然后对民乐跨断层综合观测场地2007~2008年的GPS点位速率进行校正。从计算结果可知,所用GPS天线相位中心偏差多在亚毫米级。对于距离在几千米的点位,由于各期观测所用天线的不同,使得相位中心的偏差对水平运动速率的影响多在亚毫米级;若各期观测所用天线相同,则影响多在10-2毫米量级。对高精度GPS观测来说,多期观测尽可能采用同一天线。  相似文献   

云南金平龙脖河铜矿区变钠质火山岩组分迁移及与成矿的关系   总被引：1，自引：0，他引：1       下载免费PDF全文

朱路华  戚学祥  彭松柏  熊洪  李志群 《地学前缘》2011,18(3):250-260

金平龙脖河铜矿位于哀牢山-金沙江构造带的东南端。赋矿围岩为变钠质火山岩,成矿主要类型为构造破碎蚀变岩型铜矿;围岩蚀变以绿泥石化、碳酸盐化、硅化、磁铁矿化等为主。通过对产于变钠质火山岩中不同蚀变程度和矿化程度岩、矿石的地球化学组分进行对比,计算不同岩、矿石体积的变化和组分的迁移。计算结果表明：从弱矿化变钠质火山岩到强矿化变钠质火山岩,随蚀变和矿化的增强,岩石体积分别扩容了14%、12%;组分SiO2、HREE及成矿物质Cu和S等的含量具有逐渐增加的趋势,微量元素中亲铁元素Cr、Ni也有不同程度的迁入富集;而组分CaO、MnO和LREE等的含量则逐渐降低,说明成矿过程中SiO2、HREE及成矿物质Cu和S等是由流体带入的,而CaO、MnO和LREE等则是由流体从围岩中带出的,以及成矿物质主要来源于深部流体。  相似文献