Earthquake-induced landslides in Central America   总被引：11，自引：0，他引：11  

Julian J. Bommer  Carlos E. Rodríguez   《Engineering Geology》2002,63(3-4):189-220

Central America is a region of high seismic activity and the impact of destructive earthquakes is often aggravated by the triggering of landslides. Data are presented for earthquake-triggered landslides in the region and their characteristics are compared with global relationships between the area of landsliding and earthquake magnitude. We find that the areas affected by landslides are similar to other parts of the world but in certain parts of Central America, the numbers of slides are disproportionate for the size of the earthquakes. We also find that there are important differences between the characteristics of landslides in different parts of the Central American isthmus, soil falls and slides in steep slopes in volcanic soils predominate in Guatemala and El Salvador, whereas extensive translational slides in lateritic soils on large slopes are the principal hazard in Costa Rica and Panama. Methods for assessing landslide hazards, considering both rainfall and earthquakes as triggering mechanisms, developed in Costa Rica appear not to be suitable for direct application in the northern countries of the isthmus, for which modified approaches are required.  相似文献   

Surface wave tomography of North America and the Caribbean using global and regional broad-band networks: phase velocity maps and limitations of ray theory   总被引：1，自引：0，他引：1  

Stéphanie Godey  Roel Snieder  Antonio Villaseñor  Harley M. Benz 《Geophysical Journal International》2003,152(3):620-632

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Masculinist Epistemologies and the Politics of Fieldwork in Latin Americanist Geography*     

Juanita Sundberg 《The Professional geographer》2003,55(2):180-190

Given the importance of fieldwork in Latin Americanist geography, it is intriguing to note the absence of a dialogue about the politics of fieldwork within the subdiscipline. Drawing from feminist theories about the production of knowledge, this article suggests that the silence about fieldwork is rooted in masculinist epistemologies that predominate in Latin Americanist geography. After analyzing the epistemological and pedagogical implications of masculinism, I argue for increased attention to the nexus of power and knowledge and in particular, to how the researcher's geographic location, social status, race, and gender fundamentally shape the questions asked, the data collected, and the interpretation of the data. Dialogue about these issues in our teaching and writing not only will better prepare students for fieldwork, but also has the potential to foster research that subverts rather than reproduces power inequalities.  相似文献   

AMERICAN NATIONAL IDENTITY AND THE PROGRESS OF THE NEW SOUTH IN NATIONAL GEOGRAPHIC MAGAZINE*     

DAVID R. JANSSON 《Geographical review》2003,93(3):350-369

ABSTRACT. This article examines how National Geographic Magazine's coverage of the U.S. South contributed to the production of an exalted American national identity. The framework of internal orientalism is employed to explain the role of the South as an internal other in the national discourse and to show how even positive representations of the South are often implicated in this othering. In the pages of National Geographic, the New South's progress is measured by the steps it takes away from the Old South. In highlighting the improvements made within the South, the articles provide subtle hints that the legacy of segregation, intolerance, racism, and poverty continues to haunt the region. The articles set up a spatial distinction that construes these evils as inherently southern problems, which implies that however far the New South moves away from the problematic legacy of the Old South, it will never quite reach the American ideal.  相似文献   

多层住宅砖房的地震易损性分析   总被引：5，自引：2，他引：5  

张令心  江近仁  刘洁平 《地震工程与工程振动》2002,22(1):49-55

本文采用概率方法借助于拉丁超立方采样技术和非线性地震反应过程分析对多层住宅砖房的地震易损性进行分析。其分析样本是根据多层住宅砖房目前常用设计参数值的范围选定参数的代表值，并由这些代表值构成的；分析中考虑了地震荷载、结构反应和结构承载力的不确定性。易损性曲线分别对五个不同结构破坏程度的极限状态给出。  相似文献   

北美国家高程基准面及重力异常计算方法的重大修改   总被引：1，自引：0，他引：1  

曾华霖 《物探与化探》2008,32(1):8-12

北美以及加拿大、墨西哥和美国的重力数据库进行了两项重大修改:采用国际上接受的地球椭球面,而不是习惯使用的大地水准面或海平面作为重力测点的高程基准面;改进重力异常的计算方法。对北美国家现在使用的高度校正、布格校正、地形(海洋深度)校正、间接影响校正、曲率校正、大气校正,以及均衡补偿校正,均做了不同程度的修改。  相似文献   

From incipient island arc to doubly‐vergent orogen: A review of geodynamic models and sedimentary basin‐fills of southern Central America          下载免费PDF全文

Christian Brandes  Jutta Winsemann 《Island Arc》2018,27(5)

Southern Central America is a Late Mesozoic/Cenozoic island arc that evolved in response to the subduction of the Farallón Plate beneath the Caribbean Plate in the Late Cretaceous and, from the Oligocene, the Cocos and Nazca Plates. Southern Central America is one of the best studied convergent margins in the world. The aim of this paper is to review the sedimentary and structural evolution of arc‐related sedimentary basins in southern Central America, and to show how the arc developed from a pre‐extensional intra‐oceanic island arc into a doubly‐vergent, subduction orogen. The Cenozoic sedimentary history of southern Central America is placed into the plate tectonic context of existing Caribbean Plate models. From regional basin analysis, the evolution of the southern Central American island arc is subdivided into three phases: (i) non‐extensional stage during the Campanian; (ii) extensional phase during the Maastrichtian‐Oligocene with rapid basin subsidence and deposition of arc‐related, clastic sediments; and (iii) doubly‐vergent, compressional arc phase along the 280 km long southern Costa Rican arc segment related to either oblique subduction of the Nazca plate, west‐to‐east passage of the Nazca–Cocos–Caribbean triple junction, or the subduction of rough oceanic crust of the Cocos Plate. The Pleistocene subduction of the Cocos Ridge contributed to the contraction but was not the primary driver. The architecture of the arc‐related sedimentary basin‐fills has been controlled by four factors: (i) subsidence caused by tectonic mechanisms, linked to the angle and morphology of the incoming plate, as shown by the fact that subduction of aseismic ridges and slab segments with rough crust were important drivers for subduction erosion, controlling the shape of forearc and trench‐slope basins, the lifespan of sedimentary basins, and the subsidence and uplift patterns; (ii) subsidence caused by slab rollback and resulting trench retreat; (iii) eustatic sea‐level changes; and (iv) sediment dispersal systems.  相似文献   

北美洲干旱灾害应对策略及其对中国的启示          下载免费PDF全文

王青  严登华  翁白莎  冯婧  史璇 《干旱区地理》2012,35(2):332-338

在全球气候变化背景下,各地极端气候事件有上升趋势。其中以洪涝和干旱灾害对人类生活的影响最大、最频繁。在长期应对干旱灾害的经历中,北美洲各国逐渐形成了较为完善的干旱灾害应对模式,通过立法、风险管理、制定干旱计划、工程措施与非工程措施相结合等多种手段降低干旱灾害带来的损失。通过文献查阅与综述方法,结合北美洲国家相关网站介绍...  相似文献   

Association between trophic state,watershed use,and blooms of cyanobacteria in south-central Chile     

《Limnologica》2019

An increase in the distribution and frequency of cyanobacterial blooms has been reported for many regions worldwide. Due to this fact, we studied the variables that influence the abundance of natural populations of planktonic cyanobacteria in temperate lakes of central and southern Chile. These lakes differed in trophic state and watershed use. Cyanobacteria dominated in meso- and eutrophic systems and their occurrence correlated to watershed use (tree plantations and urban). Ochrophyta and Bacillariophyta were dominant in oligotrophic lakes, where native forest dominated land usage. In these lakes, the maximum depth of the euphotic zone influenced the community structure and the genera of cyanobacteria. Dolichospermum was the most abundant, frequent, and widely distributed genus, found in oligotrophic and eutrophic lakes, forming blooms in eutrophic systems.The concentration of total phosphorus and total nitrogen positively influenced cyanobacterial abundance and bloom formation, mainly by Aphanizomenon, Aphanocapsa, Aphanothece, and Dolichospermum, and Microcystis.In contrast to many reports on their occurrence in the northern hemisphere, these genera occurred widely at less than 20 °C, forming dispersive blooms, at low temperatures in autumn and winter (10.8–15.6 °C). This shows that eutrophication is the main factor for bloom formation and these genera can form blooms independent of temperature. However, some genera, such as Microcystis, increased their abundance and presented more intense blooms (scums) at high temperatures. Our study provides baseline data to document long-term changes in lentic systems of the western south-central area of South America, including genera that could respond by increasing their abundance with eutrophication and projected climatic changes.  相似文献   

The dynamics of western North America: stress magnitudes and the relative role of gravitational potential energy, plate interaction at the boundary and basal tractions     

Lucy M. Flesch  William E. Holt  A. John Haines  Lianxing Wen  Bingming Shen-Tu 《Geophysical Journal International》2007,169(3):866-896

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