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2010年青海玉树Ms 7.1级大地震引发了一系列次生地质灾害,其中地震落石是除地震滑坡外沿断裂带及其邻侧最常见的现象。对玉树震区落石的调查发现,该区多处存在非常典型的多期地震落石分布现象,指示该区地震落石的发育与其他古地震现象类似,具有多期性和一定的原地复发性。实地调查表明,该区地震落石分布的主要特征为:多集中发育在活动断裂带附近的陡峭基岩斜坡下方,分布零散,且滚动较远,并常与古地震滑坡相伴生。初步获得的8个地震落石钙膜U系测年结果分布在距今6030±300a BP、4720±210a BP、3530±490~3560±280a BP、2010±160a BP、1090±70a BP、760±20a BP和230±20a BP年龄段,与该区古地震探槽和滑坡反映的地震事件比较吻合,进一步揭示玉树断裂带附近在全新世中晚期发生过多期可导致地表产生地震落石的事件。同时也说明,地震落石及其钙膜测年是特别值得进一步探索的潜在古地震研究方法或途径。 相似文献
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青藏铁路唐古拉山-拉萨段全新世控震断裂研究 总被引：8，自引：0，他引：8
地表调查表明,沿青藏铁路唐古拉山-拉萨段存在5条重要的全新世控震断裂带,从北到南分别是温泉盆地西缘断裂带、安多盆地北缘断裂带、崩错断裂带、谷露西缘断裂带和当雄-羊八井断裂带.构造-地貌和年代学分析结果表明,北部的温泉盆地西缘断裂和安多盆地北缘断裂带的活动强度相对比较小,平均垂直活动速率约为0.2～0.5mm/a.南侧的谷露西缘断裂带和当雄-羊八井断裂带的全新世垂直活动速率为约(15±0.5)mm/a.而中部的崩错走滑断裂带的活动强度最大,晚第四纪期间的走滑速率可达(11±4.5)mm/a.全新世断裂活动和古地震研究表明,其中温泉盆地西缘断裂带、安多盆地北缘断裂带、崩错断裂带的西北分支、当雄-羊八井断裂带的当雄段等区域未来发生强震的概率相对更大. 相似文献
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Introduction East Kunlun active fault is one of the largest sinistral slip fault zones in northern Tibetan Pla-teau. The fault tails primarily after the ancient eastern Kunlun suture zone, which was reactivatedby the northward subduction of the Indian plate beneath the Eurasian plate. The western end of thefault starts near the western flank of the Buxedaban peak in Qinghai Province. The fault then ex-tends eastwards through the Kusai Lake, Xidatan, Dongdatan, Alag Lake, Tuosuo Lak… 相似文献
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IDENTIFICATION OF PALEO-EARTHQUAKES OF LUOYUNSHAN PIEDMONT FAULT BY QUANTITATIVE MORPHOLOGY OF LIMESTONE FAULT SURFACES 
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下载免费PDF全文 The quantitative analysis of morphologic characteristics of bedrock fault surface is a useful approach to study faulting history and identify paleo-earthquake. It is an effective complement to trenching technique, specially to identifying paleo-earthquakes in a bedrock area where the trenching technique cannot be applied. This paper focuses on the Luoyunshan piedmont fault, which is an active normal fault extending along the eastern boundary of the Shanxi Graben, China. There are a lot of fault scarps along the fault zone, which supply plentiful samples to be selected to our research, that is, to study faulting history and identify paleo-earthquakes in bedrock area by the quantitative analysis of morphologic characteristics of fault surfaces. In this paper, we calculate the 2D fractal dimension of two bedrock fault surfaces on the Luoyunshan piedmont fault in the Shanxi Graben, China using the isotropic empirical variance function, which is a popular method in fractal geometry. Results indicate that the fractal dimension varies systematically with height above the base of the fault surface exposures, indicating segmentation of the fault surface morphology. The 2D fractal dimension on a fault surface shows a ‘stair-like’ vertical segmentation, which is consistent with the weathering band and suggests that those fault surfaces are outcropped due to periodic faulting earthquakes. However, compared to the results of gneiss obtained by the former researchers, the characteristic fractal value of limestone shows an opposite evolution trend. 1)The paleo-earthquake study of the bedrock fault surface can be used as a supplementary method to study the activity history of faults in specific geomorphological regions. It can be used to fill the gaps in the exploration of the paleo-earthquake method in the bedrock area, and then broaden the study of active faults in space and scope. The quantitative analysis of bedrock fault surface morphology is an effective method to study faulting history and identify paleo-earthquake. The quantitative feature analysis method of the bedrock fault surface is a cost-effective method for the study of paleo-earthquakes in the bedrock fault surface. The number of weathered bands and band height can be identified by the segment number and segment height of the characteristic fractal dimension, and then the paleoearthquake events and the co-seismic displacement can be determined; 2)The exposure of the fault surface of the Luoyunshan bedrock is affected and controlled by both fault activity and erosion. A strong fault activity(ruptured earthquake)forms a segment of fault surface which is equivalent to the vertical co-seismic displacement of the earthquake. After the segment is cropped out, it suffers from the same effect of weathering and erosion, and thus this segment has approximately the same fractal dimension. Multiple severe fault activities(ruptured earthquake)form multiple fault surface topography. The long-term erosion under weak hydrodynamic conditions at the base of the fault cliff between two adjacent fault activities(intermittent period)will form a gradual slow-connect region where the fractal dimension gradually changes with the height of the fault surface. Based on the segmentation of quantitative morphology of the two fault surfaces on the Luoyunshan piedmont fault, we identified four earthquake events. Two sets of co-seismic displacement of about 3m and 1m on the fault are obtained; 3)The relationship between the fault surface morphology parameters and the time is described as follows:The fractal dimension of the limestone area decreases with the increase of the exposure time, which reflects the gradual smoothing characteristics after exposed. The phenomenon is opposite to the evolution of the geological features of gneiss faults acquired by the predecessors on the Huoshan piedmont fault; 4)Lithology plays an important role in morphology evolution of fault surface and the two opposite evolution trends of the characteristic fractal value on limestone and gneiss show that the weathering mechanism of limestone is different from that of the gneiss. 相似文献
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青藏高原的现今地壳活动性 总被引：2，自引：0，他引：2
古近纪以来，印度板块与欧亚大陆的碰撞和持续的俯冲作用，造成了青藏高原强烈的陆内变形，引起了古造山带的复活；同时也使高原前陆盆地和内部的一些中小型盆地内数百米至数千米厚的新生代地层发生褶皱和冲断，遍布全区的逆冲推覆构造、走滑断裂和活动褶皱，在区域性的北东-南西向的构造应力作用下，导致高原地壳缩短加厚和整体向东滑移。高原的抬升是整体地、间歇性地、不均速地隆升。它经历了古近纪缓慢抬升一新近纪末至更新世快速抬升一全新世地壳振荡运动频繁的三个阶段。自7Ma至今，青藏高原累计抬高了3000～3500m，喜马拉雅山从古地中海崛起以来，至少上升了5000m。现代地热、地震发生，至今没有停止活动。 相似文献
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青藏高原东缘是全球重要的活动构造区,高原峡谷区斜坡陡峻,高位崩滑灾害多发。采用遥感解译、地面调查、钻孔勘探及测年分析等方法,研究了西藏洛隆察达沟和易贡扎木弄沟两处高位崩滑堆积体的多动力多期次演化特征。研究结果表明：(1)沿陡峻沟道发生的高位崩滑灾害多为复合成因,兼具内动力和外动力作用交替促发特征;(2)洛隆察达沟晚更新世以来的堆积物形成序列可分为4期,分别经历了以冰川作用为主的冰碛物堆积、古地震引发的高位崩滑-碎屑流堆积、气候变暖背景下的冰-岩崩滑堆积及近代重力崩滑堆积;(3)易贡扎木弄沟在过去5500年中,先后发生了8次以上较大规模崩滑堆积,测年结果显示了巨型崩滑事件存在百年数量级的复发周期,由于不同期次巨型崩滑体的成因不同,复发周期可能存在长、中、短的差异;(4)近年来受全球气候变化影响,冰-岩崩滑灾害频现,可能成为高原峡谷区高位远程地质灾害研究的焦点。本文关于高位崩滑灾害多期次演化过程的认识对于高原峡谷区重大地质灾害防灾减灾具有一定启示意义。 相似文献
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随着断层面形貌测量、宇宙成因核素测年、地球化学元素测定和光释光等一系列新兴技术的突破,基岩断层面在古地震研究方面的特征优势被不断发掘,日益成为国际古地震研究的热点与前沿。国内外学者从不同专业角度开展了大量的基岩断层面古地震研究,取得了一系列丰硕成果。本文在系统介绍基岩断层面古地震研究的进展、梳理归纳各类研究方法特点的基础上,论述了现阶段基岩断层面在研究对象的选择上存在的问题,提出了今后宜重点加强工作的若干建议,并对基岩断层面古地震研究发展前景进行了展望。 相似文献
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浅谈新时期下的地震考古及在江淮地区的应用 总被引：4，自引：0，他引：4
随着中国经济建设的发展,大规模工程开挖,以及一些遗址、古墓等的抢救性挖掘,为地震考古提供了一个极好的工作平台.本文简要回顾了国内外地震考古的研究历史、现状、所取得的研究成果;对江淮地区的历史地震资料进行了分析整理,认为历史记录有较多的遗漏,应该充分利用地震考古学手段进行古地震事件的识别;总结了一些古地震事件识别的标志,为延长地震预测预报地震事件的时序资料提供参考,同时对考古手段在目前古地震、历史地震中的应用研究进行了分析和展望. 相似文献
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基于长江经济带地区活动断裂资料的收集整理和总结,结合新的遥感解译与地表调查结果,初步归纳了该区的活动构造基本特征,梳理出直接或间接威胁重要城市群、国家级新区和区域重要交通过江通道地壳稳定性的主要活动断裂及应对建议或对策,并进一步重点指出长江中下游成都—上海沿江地区的32条重要活动断裂带及其穿越或影响到的主要城市群和重大工程。在活动断裂梳理结果基础上,总结提出长江经济带西部的强烈地壳变形与地震活动主要由印度板块与欧亚板块碰撞作用下在青藏高原东南缘地区形成的"川滇弧形旋扭活动构造体系"所控制,而中—东部地区属于印度板块与西太平洋板块共同作用下区域性挤压-剪切变形导致的具有共轭走滑断裂系统特征的"棋盘格子式"活动构造体系格局,其中需要特别关注7条典型活动断裂带的活动性及其对城市群地壳稳定性的影响。根据区域的活动构造体系、活动断裂与历史地震活动性等特点,初步归纳了该区的未来地震危险性问题及应重点关注的潜在强震危险区段,指出了典型的区域古地震地质遗迹特征及开展古地震调查研究的重要性。同时,依据长江经济带地区初步的区域地壳稳定性评价结果,认为次不稳定区和不稳定区主要集中在西部地区,而中—东部地区以次稳定区与相对稳定区为主,仅郯庐断裂带及其周边存在较明显的次不稳定区。最后,指出了长江经济带活动构造与区域地壳稳定性调查评价工作在活动断裂地质调查研究和城市活断层鉴别与地震危险性评价中面临的主要问题与挑战。 相似文献