共查询到19条相似文献,搜索用时 171 毫秒
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1976年7月28日3点42分在我国河北省唐山地区发生了7.8级强烈地震。地震的发生,是有它的区域构造背景和震区的构造条件的。深入研究这个问题,对认识地震的形成、孕育和发生是十分有意义的。唐山地震震中与深大断裂没有表现直接的联系,而是分布在不引入注目的北东向断裂上。其控制因素我们认为是包围震区的边界断裂起了重要作用。边界断裂的存在使被围限的北东向断裂得到了暂时的平衡,形成相对“闭锁”区段。当区域应力场急剧变化时,“闭锁”就被突破,产生大地震。 相似文献
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《福建地震》2000,(Z1)
一、地震基本参数表1 地震基本参数表发震时间年月日时分秒震 中 位 置微 观宏 观东经北纬东经北纬参考地名震级(MD)震源深度(Km)震中烈度 地震类型 1987080217071157°251°115°38′24°59′江西寻乌56178Ⅶ震群 微观震中与宏观震中不吻合,两者相距15Km左右,前者位于Ⅶ度极震区的外围的澄江附近。(图10-1)。图10-1 1987年8月2日寻乌地震等震线图二、地震烈度分布本次地震的宏观震中位于寻乌县城关北西3公里的文峰乡长举村附近,震中烈度Ⅶ度(图10-1)。Ⅶ度区(极震区):Ⅶ度等震线包围了寻乌县城关长宁镇及文峰乡的下河岭… 相似文献
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引言本文讨论范围包括贺兰山、六盘山、龙门山和大雪山一线以东的广大东北、华北和华南地区及台湾省(简称中国东部)。中国东部自前震旦纪结晶基底形成后(其中华南东部是加里东褶皱基底),古生代时期受地中海构造体系和西太平洋构造体系的控制,主要处于一个三面有地槽带围限、内部为地台的发展阶段。随着属于地中海构造体系的天山和蒙古-大兴安岭地槽带、昆仑山-秦岭地槽带和川西-滇西地槽带于古生代至三迭纪期间逐渐褶皱迴返结束地槽生命后,中国东部受西太平洋构造体系的影响便相应地明显起来,成为中国东部中新生代地质构造发展的主导因素。 相似文献
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基于最新重力场模型对2014年于田Ms7.3地震震区的重力异常特征进行分析, 并应用Crust1.0地壳模型计算得到震区的深部构造形态, 结果显示: 震中位于地壳厚度陡变带上.同2008年于田Ms7.3地震相比, 震中虽位于不同位置, 但发震机制均与深部地壳结构变化密切相关.统计研究区内历史地震活动性与重力异常之间的关系, 发现震中的自由空气异常与地形存在明显的线性相关性, 而布格异常和均衡异常的结果则明显不同.进一步地分别计算不同重力异常的水平总梯度和线性信号, 结果表明: 重力异常梯度量与地形的相关特性更明显.研究表明: Ms7.0以上大震活动与重力异常之间具有明显的统计特性学, 这可能与重力异常反映的深部结构和壳内质量分布的不均匀有关. 相似文献
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Ten moderate to large (magnitude 6–7) earthquakes have occurred in southwestern British Columbia and northwestern Washington in the last 130 years. A future large earthquake close to Vancouver, Victoria, or Seattle would cause tens of billions of dollars damage and would seriously impact the economies of Canada and the United States. An improved understanding of seismic hazards and risk in the region has been gained in recent years by using geologic data to extend the short period of instrumented seismicity. Geologic studies have demonstrated that historically unprecedented, magnitude 8 to 9 earthquakes have struck the coastal Pacific Northwest on average once every 500 years over the last several thousand years; another earthquake of this size can be expected in the future. Geologic data also provide insights into the likely damaging effects of future large earthquakes in the region. Much of the earthquake damage will result directly from ground shaking, but damage can also be expected from secondary phenomena, including liquefaction, landslides, and tsunamis. Vancouver is at great risk from earthquakes because important infrastructure, including energy and transportation lifelines, probably would be damaged or destroyed by landslides and liquefaction-induced ground failure. 相似文献
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程强 《中国地质灾害与防治学报》2011,22(3):1-6
为研究汶川地震崩滑灾害主要影响因素,在掌握汶川地震灾区公路沿线地震崩滑灾害资料基础上,选取典型段进行灾害统计分析,研究表明动力条件下斜坡失稳主要受斜坡岩体结构特征、地震动峰值加速度和斜坡动力响应特征三方面因素影响。地震动峰值加速度越高,地震崩滑灾害越发育。斜坡动力响应特征主要取决于地形地貌和地层岩性,陡坡硬岩段为地震崩滑灾害高发区。斜坡岩体结构是控制斜坡变形破坏的主要因素,从研究斜坡动力失稳角度,提出了斜坡岩体结构类型的划分,分为土层及强风化层——基岩二元结构、块状结构、层状及似层状结构、碎裂结构、土层等5个大类12个亚类。 相似文献
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The Ms 8.0 Wenchuan earthquake of May 12, 2008 is one of the most disastrous earthquakes in China. The earthquake triggered tens of thousands of landslides over a broad area, including shallow, disrupted landslides, rock falls, deep-seated landslides, and rock avalanches, some of which buried large sections of some towns and dammed the rivers. The purpose of this study is to investigate correlations between the occurrence of landslides with geologic and geomorphologic conditions, and seismic parameters. Over 56,000 earthquake-triggered landslides, with a total area of 811 km2, are interpreted using aerial photographs and remote sensing images taken following the earthquake. The spatial distribution of these landslides is analyzed statistically using both landslide-point density (LPD), defined as the number of landslides per square kilometer, and landslide-area density (LAD), the percentage of the area affected by landslides, to determine how the occurrence of landslides correlates with distance from the epicenter, distance from the major surface rupture, seismic intensity and peak ground acceleration (PGA), slope angle, slope aspect, elevation, and lithology. It is found that both LAD and LPD have strong positive correlations with slope steepness, distance from the major surface rupture and seismic intensity, and that Pre-Sinian schist, and Cambrian sandstone and siltstone intercalated with slate have the most concentrated landslide activities, followed by the Permian limestone intercalated with shale, and Devonian limestone. Statistical analyses also indicate that the major surface rupture has influence on the spatial distribution of landslides, because LAD and LPD are relatively higher on the hanging wall than on the footwall. However, the correlation between the occurrence of landslides with distance from the epicenter of the earthquake is complicated, rather than a relatively simple negative correlation as found from other reported cases of earthquakes. This is possibly due to complicated rupture processes of the earthquake. 相似文献
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利用Newmark方法进行地震滑坡制图——以映秀研究区为例 总被引:1,自引:0,他引:1
2008年汶川5.12地震触发了大量滑坡,这些滑坡所造成的损失甚至超过地震本身。在地震区映秀,获取了地震边坡稳定性分析所需的地震滑坡编目图、强震监测数据、1:50000地质图、岩组单元的物理力学数据及基于1:50000地形图得到的DEM数据,所有这些数据都通过GIS(ilwis3.6)进行了矢量化及栅格化(10m)处理。基于上述数据,利用Newmark方法对每个单元格的变形及位移进行计算分析,然后通过Newmark位移与地震滑坡编目图进行对比分析,建立边坡失稳概率与Newmark位移之间的关系,用于地震滑坡预测及编图,为地震应急及灾后重建提供科学依据。 相似文献
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在山区,地震诱发滑坡造成的人员伤亡往往占到地震总伤亡人数的一半以上,尤其是在黄土地区,由于地震造成的黄土滑坡具有运动距离远等特征,其灾难性更严重。针对地震诱发黄土斜坡的失稳峰值加速度、临界位移和运动距离等问题,本文利用离散元(PFC)方法,通过对室内三轴实验的应力-应变曲线进行标定和高精度航拍三维地形数据进行转化,以宁夏海口村黄土斜坡为研究对象,开展三维地震作用下斜坡失稳破坏和运动过程的数值模拟研究。通过监测不同位置在地震作用下的应力分量,计算监测点的p、q值并与室内三轴实验所得到p-q破坏线进行比较,获得斜坡破坏过程中的应力路径。结合颗粒的监测位移,获得斜坡失稳破坏的临界位移,得出该黄土斜坡失稳峰值加速度为0.135 g,临界位移为50 cm。同时根据不同地面环境条件,预测了在不同摩擦系数下斜坡失稳后的危害范围,为黄土地区边坡工程的抗震设计及防震减灾工作提供一种新的可视化方法。 相似文献
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2014年8月3日, 发生在中国云南省鲁甸县的MS 6.5(Mw 6.1)级地震造成了严重的灾难, 本次地震还触发了至少1024处面积大于100m2的滑坡。本文的目的是利用同震滑坡的空间分布与规模分布特征分析本次地震的震源性质与破裂过程。鲁甸地震同震滑坡分布区域的长轴展布方向呈北西南东方向, 结合区域活动构造分布, 认为其发震构造是北西南东方向的包谷垴小河断裂。地震滑坡多分布在震中的南东方向, 表明了其破裂方向是自北西向南东扩展。滑坡分布区北西部分滑坡分布较分散, 规模总体较小; 而南东部分滑坡分布相对集中, 且有几处规模较大。由于隐伏断裂型地震比地表破裂型地震触发滑坡分布面积广、数量多, 但规模较小, 因此判断发震构造的北西部分可能由于破裂面较深而隐伏于地下, 而南东部分可能产生了地表破裂且破裂面较浅。这一判断得到了野外调查结果的验证。鲁甸地震破裂自北西向南东是由深部向浅部斜向上扩展的, 这种破裂面斜向上扩展的破裂特征或许是导致鲁甸地震灾害非常严重的重要原因之一。 相似文献
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Tapas R. Martha Priyom Roy Ritwik Mazumdar K. Babu Govindharaj K. Vinod Kumar 《Landslides》2017,14(2):697-704
High magnitude earthquakes trigger numerous landslides and their occurrences are mainly controlled by terrain parameters. We created an inventory of 15,551 landslides with a total area of 90.2 km2 triggered by the 2015 Mw 7.8 (Gorkha) and Mw 7.3 (Dolakha) earthquakes in Nepal, through interpretation of very high resolution satellite images (e.g. WorldView, Pleiades, Cartosat-1 and 2, Resourcesat-2). Our spatial analysis of landslide occurrences with ground acceleration, slope, lithology and surface defomation indicated ubiquitous control of steep slope on landslides with ground acceleration as the trigger. Spatial distribution of landslides shows increasing frequency away from the Gorkha earthquake epicentre up to 130 km towards east, dropping sharply thereafter, which is an abnormal phenomenon of coseismic landslides. Landslides are laterally concentrated in three zones which matches well with the seismic rupture evolution of Gorkha earthquake, as reported through teleseismic measurements. 相似文献