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51.
STUDY ON THE DISTRIBUTION PATTERN OF EARTHQUAKE- TRIGGERED LANDSLIDES BASED ON SEISMIC LANDSLIDE SUSCEPTIBILITY ANALYSIS: A CASE STUDY OF LANDSLIDES TRIGGERED BY THE MS6.5 LUDIAN EARTHQUAKE IN 2014 
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下载免费PDF全文 On August 3, 2014, an MW6.5 earthquake occurred in Ludian County, Yunnan Province, which triggered significant landslides and caused serious ground damages and casualties. Compared with the existing events of earthquake-triggered landslides, the spatial distribution of co-seismic landslides during the Ludian earthquake showed a special pattern. The relationship between the co-seismic landslides and the epicenter or the known faults is not obvious, and the maximum landslide density doesn't appear in the area near the epicenter. Peak ground acceleration (PGA), which usually is used to judge the limit boundary of co-seismic landslide distribution, cannot explain this distribution pattern. Instead of correlating geological and topographic factors with the co-seismic landslide distribution pattern, this study focuses on analyzing the influence of seismic landslide susceptibility on the co-seismic distribution. Seismic landslide susceptibility comes from a calculation of critical acceleration values using a simplified Newmark block model analysis and represents slope stability under seismic loading. Both DEM (SRTM 90m)and geological map (1 ︰ 200￣￣000)are used as inputs to calculate critical acceleration values. Results show that the most susceptible slopes with the smallest critical accelerations are generally concentrated along the banks of rivers. The stable slopes, which have the larger critical accelerations and are comparably stable, are in the places adjacent to the epicenter. Comparison of the distribution of slope stability and the real landslides triggered by the 2014 MW6.1 Ludian earthquake shows a good spatial correlation, meaning seismic landslide susceptibility controls the co-seismic landslide distributions to a certain degree. Moreover, our study provides a plausible explanation on the special distribution pattern of Ludian earthquake triggered landslides. Also the paper discusses the advantages of using the seismic landslide susceptibility as a basic map, which will offer an additional tool that can be used to assist in post-disaster response activities as well as seismic landslides hazards zonation. 相似文献
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CHARACTERISTICS AND FORMATION MECHANISM OF LARGE ROCK AVALANCHES TRIGGERED BY THE LUDIAN MS6.5 EARTHQUAKE AT HONGSHIYAN AND GANJIAZHAI 下载免费PDF全文
下载免费PDF全文 The 3 August 2014 Ludian, Yunnan MS6.5 earthquake has spawned more than 1, 000 landslides which are from several tens to several millions and over ten millions of cubic meters in volumes. Among them, the Hongshiya and Ganjiazai landslides are the biggest two with volumes over 1 000×104m3. The Hongshiya and Ganjiazai landslides are two typical landslides, the former belongs to tremendous rock avalanche, and the latter belongs to unconsolidated werthering deposit landslide developed in concave mountain slope. Based on field investigations, causes and formation mechanism of the two landslides are discussed in this study. The neotectonic movement in the area maintains sustainable uplifting violently all the time since Cenozoic. The landform process accompanied with the regional tectonic uplifting is the violent downward erosion along the Jinshajiang River and its tributary, forming landforms of high mountains and canyons, deeply cut valleys, with great height difference. The regional seismo-tectonics situation suggests that:Ludian earthquake region is situated on the southern frontier boundary of Daliangshan secondary active block, and is seismically the strongest active area with one earthquake of magnitude greater than M5.0 occurring every 6 years. Frequent and strong seismicity produces accumulated effects on the ground rock to gradually lower the mechanical strength of slopes and their stability, which is the basis condition to generate large-scale collapse and landslide at Hongshiyan and Ganjiazhai. The occurring of Hongshiyan special large rock avalanche is associated with the large terrain height difference, steep slope, soft interlayer structure and unloading fissures and high-angle joints. The formation mechanism of Hongshiyan rock avalanche may have three stages as follows:Stage 1, when P wave arriving, under the situation of free surface, rocks shake violently, the pre-existent joints(in red)parallel to and normal to the river and unloading cracks are opened and connected. Stage 2, on the basis of the first stage, when S wave arriving, the ground movement aggravates. Joints(in green)along beds develop further, resulting in rock masses intersecting each other. Stage 3, rock masses lose stability, sliding downward, collapsing, and moving over a short distance along the sliding surface to the inside of the valley, blocking the river to form the dammed lake. The special large landslide at Ganjiazhai is a weathering layer landslide occurring in the middle-lower of a large concave slope. Its formation process may have two stages as follows:Firstly, under strong ground shaking and gravity, the ground rock-soil body around moves and assembles to the lower of the central axis of the large concave slope, which suffers the largest earthquake inertia force and firstly yields plastic damage to generate compression-expansion deformation, because of the largest water content and volume-weight within the loose soil of it. Secondly, in view of the steep slope, along with the compression, the plastic deformation area enlarges further in the lower of slope, giving rise to a tensional stress area along the middle of the slope. As soon as the tensional stress exceeds the tensile strength of the weathering layer, a tensional fracture will occur and the landslide rolls away immediately making use of momentum. This two large landslides are the basic typical ones triggered by the MS6.5 Ludian earthquake, and their causes and mechanism have a certain popular implication for the landslides occurring in this earthquake region. 相似文献
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2014年8月3日16时30分,云南省昭通市鲁甸县发生6.5级地震,此次地震危害性较大。在快速收集震区地震烈度分布、地形状况、土地利用/覆盖现状、乡镇人口、居民点分布、房屋建筑物以及高分辨率遥感图像等信息的基础上,应用GIS空间分析和定量评估模型,对重灾区自然环境状况,受灾人口、房屋建筑物及道路交通等敏感受体影响,牛栏江沿岸次生地质灾害风险等级,坡耕地退耕及水土流失防治4个方面进行了快速评估,并针对震区人员救助、地质次生灾害防治以及灾后重建生态治理提出了科学的对策建议。 相似文献
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在对滇东北地区地下流体观测资料进行综合评估的基础上,选择评估达到Ⅰ、Ⅱ类的观测资料,采用日值、五日均值、旬均值、相关矩平、K-L拟合分析、CF分析等方法,对2003～2012年以来滇东北地区的5组MS≥5.0地震进行震例回顾总结.归纳震前该区地下流体前兆异常的时空演化特征,发现前兆异常数量在时间上具有阶段性,异常项数在震前6个月开始增多,震前3个月达到最大值,临震前1个月部分异常转折结束,异常数量出现降低;异常在空间演化上具有震前3个月向震中收缩的特点.80％的震例表明震中距100 km范围内的观测点异常比例远高于100 km范围外的观测点异常比例.将结果外推应用于2014年8月3日鲁甸6.5级地震,发现他们具有较好的一致性,表明滇东北地区MS≥5.0地震前地下流体的异常特征具有普适性. 相似文献
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烈度与余震分布显示2014年云南鲁甸MW6.1(MS6.5)地震的发震构造较复杂.为深入了解鲁甸地震的发震断层与破裂特征,本文考虑了单一断层破裂和共轭断层破裂的情况,对震中距250km范围内的近震资料(宽频带资料和强震资料)和远震体波资料进行了反演,得到了鲁甸地震的破裂过程,探讨了滑动分布与余震分布之间的关系.根据反演得到的滑动分布、震源时间函数和波形拟合,认为鲁甸地震是一次在北西向主压应力与北东向主张应力的统一应力场下发生的两条共轭断层先后破裂的一次复杂地震事件.在破裂开始后0~2s,破裂主要发生在ENE—WSW向(近东西向)的断层上,随后NNW—SSE向(近南北向)断层开始破裂,释放了大部分的地震矩.由于近南北向断层南段(即震中以南)的破裂规模较大,且以左旋走滑为主,对近东西向断层的西段起到了一定程度的解锁作用,可能是震中以西无明显主震破裂但存在密集余震分布的主要原因. 相似文献
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2014年8月3日云南鲁甸（MW6.1,MS6.5）地震是一次规模不大、但灾害严重的走滑型地震事件.受走滑型地震辐射图型的影响,远震地震资料在特定方位上信噪比不高,给此次地震发震断层面的确定造成了一些干扰.本文概述了鲁甸地震发生后2.4小时发布的作为地震应急响应的破裂过程快速反演工作,以及随后对反演结果的修订工作.修订结果中,两个双力偶节面的反演都显示破裂方向朝地表和走向方向扩展.结合现有的烈度分布和余震精确定位结果,根据破裂方向和烈度与余震分布的优势方向的一致性,确定鲁甸地震是发生在走向162°,倾角86°的近乎垂直于地面的以左旋走滑为主的断层面上的一次破裂事件.根据破裂过程反演得到的震源时间函数,大部分地震矩在破裂开始后2~5 s内集中释放. 比较集中的地震矩释放过程可能是此次地震面波震级明显高于矩震级,且造成严重地震灾害的原因之一. 相似文献
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大凉山次级块体内强震发生的构造特征与2014年鲁甸6.5级地震对周边断层的影响 总被引：4，自引：3，他引：1
2014年8月3日,在云南鲁甸发生MS6.5地震.该地震位于巴颜喀拉块体、川滇块体与华南块体三者之间的以挤压和左旋走滑为主要活动特征的大凉山次级块体内部.该次级块体吸收了来自川滇块体和巴颜喀拉块体的挤压作用,主要以各边界断裂带的挤压作用和内部大凉山断裂带、峨边断裂带等NNW向的左旋走滑次级断裂为主要特征;在历史上大凉山次级块体边界上以7级以上强震活动为主要特征,而在次级块体内部则以5级地震频繁活动为主.2014年鲁甸MS6.5地震发生在逆冲走滑断裂带内部的NNW向左旋走滑断裂上,该地震主要受到了发生在小江断裂带上的1733年M73/4和则木河断裂带上的1850年M71/2强震的影响,这两次地震对2014年鲁甸MS6.5地震有促进作用,而2014年鲁甸6.5级地震促进了2014年10月1日越西5.0级地震的发生,此外鲁甸地震对大凉山断裂带北段、峨边断裂带、昭通-鲁甸断裂带东段以及则木河断裂带南段有一定的库仑应力增强作用. 相似文献
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本文努力探索地震活动性定量化前兆的检测方法,针对Region-Time-Length(RTL)算法在空间异常分析中的不足,根据新提出的综合衡量区域地震活动水平的物理参数——RTL面积分(I_(RTL)),定量分析了2014年鲁甸M_S6.5地震前地震活动时空变化,并与2012年彝良M_S5.7、5.6地震作了对比,研究结果显示这些地震前都检测到地震活动增强.彝良地震前地震活动增强异常主要分布在则木河断裂和昭通—莲峰断裂带西段的交汇区,鲁甸地震前异常主要分布在昭通—莲峰断裂带、马边断裂带及周边地区.以上地震活动增强异常区的I_(RTL)随时间呈现由小变大,至峰值后回落的特征.彝良地震和鲁甸地震均发生于I_(RTL)峰值后数月,这表明I_(RTL)峰值对地震发生可能有一定的指示意义.鲁甸地震后,对周边地区地震活动跟踪研究检测到地震活动增强现象,且自2015年I_(RTL)呈上升趋势,目前I_(RTL)值已超过鲁甸地震前的峰值水平,也许更强的地震正在孕育,所以川滇交界东边界中部仍存在发生强震的可能.以上研究为我们认识鲁甸地震的孕震过程和地震前兆研究提供了新的认识. 相似文献
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2014年云南鲁甸M_S6.5地震异常及预测 总被引：1，自引：0，他引：1
通过分析2014年云南鲁甸MS6.5地震前震情跟踪过程中的显著异常,认为云南境内M≥6.5地震的长时间平静、M≥6地震的丛集活动以及M≥3地震月频次高值是震前云南地区地震活动异常的显著特征;滇东北地区M≥5地震活动的韵律特征、2008年后3、4级地震活动显著增强以及2014年以来滇东北地区的高水位异常是判定滇东北地区存在M≥6地震的主要依据。在多个地震同时孕育的过程中,对判定哪个危险区先发震是困难的,但每次地震都有新的前兆异常出现,为成组地震连发过程中,新地震的识别提供了依据。云南地区3级地震月频次异常和前兆突变异常增多是鲁甸MS6.5地震短期阶段最显著的异常特征。 相似文献