Imaging the rupture process of the 10 January 2018 MW7.5 Swan island,Honduras earthquake*          下载免费PDF全文

Chuang Cheng  Dun Wang 《地震科学（英文版）》2020,33(4):194-200

The 10 January 2018 M_W7.5 Swan island, Honduras earthquake occurred on the Swan island fault, which is a transform plate boundary between the North American and Caribbean plates. Here we back-project the rupture process of the earthquake using dense seismic stations in Alaska, and find that the earthquake ruptured at least three faults (three stages) for a duration of ~40 s. The rupture speed for the longest fault (stage 3) is as fast as 5 km/s, which is much faster than the local shear wave velocity of ~4 km/s. Supershear rupture was incidentally observed on long and straight strike-slip faults. This study shows a supershear rupture that occured on a strike-slip fault with moderate length, implying that supershear rupture might commonly occur on large strike-slip earthquakes. The common occurrence of supershear rupture on strike-slip earthquakes will challenge present understanding of crack physics, as well as strong ground motion evaluation in earthquake engineering.  相似文献   

水资源约束下的河西走廊城市经济脆弱性时空演变及其影响因素     

张戬  陈佳  黄馨  王子侨 《中国沙漠》2019,39(1):203-211

城市经济脆弱性作为当前脆弱性研究中的重要领域，为人-地系统耦合研究提供了新的视角，并为城市可持续健康发展提供有益的决策支持和管理方法。依据城市经济脆弱性内涵，基于暴露度、敏感性、适应能力构建了城市经济脆弱性评价指标体系，运用熵权TOPSIS法评价河西走廊地区及区域内五市的城市经济脆弱性，并采用障碍度模型识别影响区域城市经济脆弱性变化的因素。结果显示：（1）2006—2015年，河西走廊地区城市经济脆弱性呈现出先曲折下降（2006—2011年）再波动上升趋势（2012—2015年）；（2）河西走廊地区的城市经济脆弱性具有明显的空间特征，经历了东西高、中部低到整体较高的演变过程；（3）阻碍河西走廊地区城市经济脆弱性降低的障碍因子由适应能力逐步转变为暴露度。针对河西走廊地区各市主要障碍因子，提出针对性优化措施。  相似文献   

2017年九寨沟M_S7.0地震对周围地区的静态应力影响          下载免费PDF全文

靳志同  万永革  刘兆才  黄骥超  李瑶  杨帆 《地球物理学报》2019,62(4):1282-1299

基于九寨沟M_S7.0地震的破裂模型及均匀弹性半空间模型，本文计算了该地震在周围主要活动断层上产生的库仑应力变化、在周围地区产生的应力场和位移场和同震库仑应力变化对余震的触发.结果表明：（1）九寨沟地震造成虎牙断裂中段库仑破裂应力有较大增加，已经超过0.01 MPa的阈值，虎牙断裂北段、塔藏断裂中段和岷江断裂北段北部的库仑破裂应力有较大降低，因此尤其要注意虎牙断裂中段的危险性.（2）水平面应力场在该地震震中东西两侧增加（拉张），张应力起主要作用.在震中南北两侧降低（压缩），压应力起主要作用.从水平主压和主张应力方向来看，均呈现出条形磁铁的磁场形态.从剖面上的应力场来看，在上盘的面膨胀区域内，大部分点的主张应力方向与地表是垂直的，在其他区域内，主张应力和主压应力均以震中为中心，向外呈辐射状.（3）从地表水平位移场来看，震中东西两侧物质朝震中位置汇聚，南北两侧物质向外流出，在震中处的最大水平位移量达43 mm.从地表垂直位移场来看，震中南北两侧出现明显的隆升，隆升最大值达56.8 mm.震中东西两侧出现明显的沉降，沉降最大值达74.5 mm.从剖面的位移场来看，九寨沟地震为左旋走滑地震，且有一定的正断成分.由分析可以推测该断层破裂在大致22~26 km的深度上就截止了.并推测下盘物质运动的动力来自震源北东东方向（四川块体）深度在6~30 km的下盘下层物质，上盘物质运动的动力来自震源北西西方向（巴颜喀拉块体）深度在0~6 km的上盘上层物质.（4）通过计算不同深度上主震对余震的触发作用可知，主震后的最大余震受到了主震的触发作用，多数其他余震也受到主震的触发作用.主震的发生促使了库仑应力增加地区余震的发生，抑制了一部分库仑应力减少地区余震的发生.  相似文献   

西南大西洋阿根廷滑柔鱼资源时空分布研究   总被引：2，自引：0，他引：2  

侯庆联  陈新军  汪金涛 《海洋科学》2019,43(5):103-109

通过了解西南大西洋阿根廷滑柔鱼(Illexargentinus)资源丰度年间变化规律,从而对阿根廷滑柔鱼的资源可持续开发与管理打下基础。作者根据2012～2017年西南大西洋阿根廷滑柔鱼生产统计数据,利用灰色关联评价等数理方法对西南大西洋资源渔场的时空分布特征进行了分析。结果表明,2012～2017年间西南大西洋阿根廷滑柔鱼渔场重心主要在经度上分布于58°W～63°W海域,纬度主要集中在41°～44°S、47°～48°S两个区域,高平均网次产量(10 t/网)的海域主要在57°W～67°W、41°S～42°S和57°W～67°W、44°S～50°S海域。灰色关联度表明:6年间,以2015年滑柔鱼资源状况最好,其次是2014年,2012年最差,2013年、2016年和2017年处于中间水平。利用灰色关联分析的阿根廷滑柔鱼资源丰度变化趋势可用于其资源的可持续开发与管理。  相似文献   

Geography Deserts: State and Regional Variation in the Formal Opportunity to Learn Geography in the United States, 2005–2015     

Mark C. Jones  Marcos Luna 《The Journal of geography》2019,118(2):88-100

The formal opportunity to learn geography in the United States is unevenly distributed across space, creating possible geography deserts. Data on the number of exams taken in Advanced Placement Human Geography (APHG) and bachelor’s degrees earned in geography are mapped at the state and regional scales. Normalized rates are ranked and grouped into quintiles. For APHG exams, states in the southeastern region of the United States are in the uppermost quintiles while states in the northeastern region are in the lowermost quintiles. The pattern for bachelor’s degrees in geography is somewhat the spatial inverse of that for APHG.  相似文献   

Ⅶ度抗震设防下牧区居住建筑节能技术研究   总被引：1，自引：1，他引：0       下载免费PDF全文

薛芸 《地震工程学报》2018,40(1):60-65

对抗震设防下的牧区居民建筑进行节能设计,在提高能源利用率及降低能源消耗方面具有重要意义。传统的建筑节能技术主要通过降低建筑的热能消耗来提高能源利用,存在节能效果差且单一的问题。对此,在Ⅶ度抗震设防下,采用ANSYS软件,引入Block Lanczos法对牧区居住建筑结构的模态进行分析,计算出建筑地震作用,并通过分析牧区居住建筑围护结构及门窗材质来优化建筑节能技术。实验结果表明,在内蒙古牧区居住建筑采用改进提出的建筑节能技术,可有效降低能源消耗,从而能够有效利用能源,使其具有一定的优势。  相似文献   

Rupture model of the 2013 M_W 6.6 Lushan (China) earthquake constrained by a new GPS data set and its effects on potential seismic hazard          下载免费PDF全文

Rumeng Guo  Yong Zheng  Faqi Diao  Xiong Xiong  Jiao Xu 《地震科学（英文版）》2018,31(3):117-125

Vertical records are critically important when determining the rupture model of an earthquake, especially a thrust earthquake. Due to the relatively low fitness level of near-field vertical displacements, the precision of previous rupture models is relatively low, and the seismic hazard evaluated thereafter should be further updated. In this study, we applied three-component displacement records from GPS stations in and around the source region of the 2013 MW6.6 Lushan earthquake to re-investigate the rupture model.To improve the resolution of the rupture model, records from both continuous and campaign GPS stations were gathered, and secular deformations of the GPS movements were removed from the records of the campaign stations to ensure their reliability. The rupture model was derived by the steepest descent method(SDM), which is based on a layered velocity structure. The peak slip value was about 0.75 m, with a seismic moment release of 9.89 × 10~(18) N·m, which was equivalent to an M_W6.6 event. The inferred fault geometry coincided well with the aftershock distribution of the Lushan earthquake. Unlike previous rupture models, a secondary slip asperity existed at a shallow depth and even touched the ground surface. Based on the distribution of the co-seismic ruptures of the Lushan and Wenchuan earthquakes, post-seismic relaxation of the Wenchuan earthquake, and tectonic loading process, we proposed that the seismic hazard is quite high and still needs special attention in the seismic gap between the two earthquakes.  相似文献   

港湾中海啸流的模拟及其时空演变特征对输入条件不确定性的响应分析          下载免费PDF全文

王培涛  闪迪  侯京明  王岗  高义  任智源  范婷婷  王宗辰  王君成 《地球物理学报》2018,61(4):1325-1340

一直以来，海啸波特征作为表征海啸潜在破坏性的参数指标得到了广泛应用，特别是针对近场极端海啸事件造成的灾害来说，这种表征具有较好的适用性.然而总结分析历史海啸事件造成的损失发现：在远场近岸及港湾系统中，海啸诱导的强流却是造成损失的主要原因.陆架或港湾振荡导致海啸波幅快速升降诱发强流，可能促使港工设施受到威胁及损害，进而对海啸预警服务及海事应急管理提出了新的挑战.因此，全面理解与评估海啸在港湾中诱发的灾害特征，探索港湾中海啸流的数值模拟方法，发展针对港湾尺度的海啸预警服务指导产品尤为迫切.受限于海啸流验证数据的缺乏及准确模拟海啸流技术方法的诸多不确定性，大部分海啸数值模拟研究工作主要是针对水位特征的研究及验证，可能导致对港湾中海啸灾害危险性认识的曲解与低估.本研究基于非线性浅水方程，针对夏威夷群岛三个典型港湾建立了精细化海啸数值模型（空间分辨率达到10 m），并联合有限断层破裂模型计算分析了日本东北地震海啸在三个港湾及其邻近区域的海啸特征，波、流计算结果与实测结果吻合较好，精细化的海啸港湾模型模拟结果可信.模拟发现港湾中较小的波幅，同样可以产生强流.综合分析日本东北地震海啸波、流特征对输入条件不确定性的响应结果发现：港湾中海啸波-流能量的空间分布特征差异较大，这与港湾系统中海啸波的驻波特性相关；相比海啸波幅空间特征，海啸流特征具有更强的空间敏感性；海啸流时空分布特征对输入条件的不确定性响应比海啸波幅对这些不确定性的响应更强，海啸流的模拟与预报更有挑战性；不确定性对海啸流计算精度的影响会进一步传导放大港湾海啸流危险性的评估及对港工设施产生的应力作用的误差，合理的输入条件对海啸流的精确模拟至关重要.最后，希望通过本文的研究可以从海啸波-流特征角度更加全面认识近岸海啸灾害特征，拓展海啸预警服务的广度与深度，从而为灾害应急管理部门提供更加科学合理的辅助决策产品.  相似文献   

Analysis of city centrality based on entropy weight TOPSIS and population mobility:A case study of cities in the Yangtze River Economic Belt     

罗静  陈四云  孙璇  朱媛媛  曾菊新  陈广平 《地理学报(英文版)》2020,30(4):515-534

Based on statistical data and population flow data for 2016,and using entropy weight TOPSIS and the obstacle degree model,the centrality of cities in the Yangtze River Economic Belt(YREB)together with the factors influencing centrality were measured.In addition,data for the population flow were used to analyze the relationships between cities and to verify centrality.The results showed that:(1)The pattern of centrality conforms closely to the pole-axis theory and the central geography theory.Two axes,corresponding to the Yangtze River and the Shanghai-Kunming railway line,interconnect cities of different classes.On the whole,the downstream cities have higher centrality,well-defined gradients and better development of city infrastructure compared with cities in the middle and upper reaches.(2)The economic scale and size of the population play a fundamental role in the centrality of cities,and other factors reflect differences due to different city classes.For most of the coastal cities or the capital cities in the central and western regions,factors that require long-term development such as industrial facilities,consumption,research and education provide the main competitive advantages.For cities that are lagging behind in development,transportation facilities,construction of infrastructure and fixed asset investment have become the main methods to achieve development and enhance competitiveness.(3)The mobility of city populations has a significant correlation with the centrality score,the correlation coefficients for the relationships between population mobility and centrality are all greater than 0.86(P<0.01).The population flow is mainly between high-class cities,or high-class and low-class cities,reflecting the high centrality and huge radiating effects of high-class cities.Furthermore,the cities in the YREB are closely linked to Guangdong and Beijing,reflecting the dominant economic status of Guangdong with its geographical proximity to the YREB and Beijing's enormous influence as the national political and cultural center,respectively.  相似文献   

环塔里木盆地绿洲城市发展与水环境质量协调度     

孜比布拉·司马义  杨胜天  杨晓东  王蕾  肖合来提·巴义 《中国沙漠》2020,40(1):88-96

解决好新疆环塔里木盆地绿洲城市发展与水环境质量之间的关系，对"一带一路"倡议顺利实施及新疆社会稳定具有十分重要的作用。基于2004-2017年环塔里木盆地绿洲城市发展与水环境变化状况，构建城市发展与水环境质量的综合评价模型及二者的协调度模型，以探讨环塔里木盆地绿洲城市发展、水环境质量变化及二者的协调关系。结果表明：2004-2017年，（1）环塔里木盆地绿洲城市发展综合指数呈现出逐年稳定上升的趋势，经济发展和城镇空间规模扩大是环塔里木盆地绿洲城市发展的主要形式；（2）环塔里木盆地绿洲城市的水环境质量综合指数呈现出逐年降低的趋势，水环境质量形势严峻；（3）环塔里木盆地绿洲城市发展-水环境质量系统的协调度呈现倒U型的稳定发展趋势，但总体上两者的协调度较低，城市发展和水环境质量之间的矛盾日益突出。  相似文献