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1.
以ARCGIS系列软件和VS 2010、SQL Server 2008为平台, 通过融合集成活动构造、地震地质和国家基础地理信息, 在初步建立的青藏高原东南缘活动构造空间数据库系统基础上, 利用地震围空区方法, 针对研究区进行区域大地震危险性中长期预测分析。通过地震信息分时间、分震级的整理与数据输出, 分析汇总了11例M≥7.0大震震例的地震空区活动图像以及围空区发震震级与围空区特征与参数。在总结出的经验公式基础上, 进一步利用1950-2012年的M≥5.0地震数据, 对该区地震围空区的发生与发育状况进行了初步分析与研究, 并对未来可能发生大震的发震位置及震级进行了综合分析。研究结果表明, 玉树-鲜水河-小江断裂带所围限的青藏高原东南缘地区存在6个比较突出的与区域重要的晚第四纪活动构造带或断裂带相对应的大地震围空区, 分别是错那-沃卡裂谷, 东喜马拉雅构造结, 安宁河-则木河断裂, 南汀河断裂-红河断裂, 畹町断裂-南汀河断裂, 澜沧-景洪断裂东段。这些围空区中主要活动断裂带的晚第四纪活动性与历史地震活动状况也都显示出未来几年至几十年存在发生大地震的危险性, 在今后的地震预报工作中应给予特别关注。应用实践表明, 通过活动构造数据库的建设可快速有效地实现对区域大地震围空区的动态分析、辨别及大地震危险性初判。 相似文献
2.
2015尼泊尔大地震及喜马拉雅造山带未来地震趋势 总被引：1，自引：1，他引：0
2015年4月25日尼泊尔Ms 8.1级大地震是发生在喜马拉雅造山带中段的低角度逆冲断层运动, 特点是震源很浅, 震中烈度达Ⅺ度, 震害严重。破裂带走向北西西—南东东, 穿越尼泊尔首都加德满都, 使首都建筑遭受严重破坏。该震是1934年以来尼泊尔最大地震, 标志着喜马拉雅带自1950年以来半个世纪的平静期已经结束。自2005年进入新活动期, 至2015年尼泊尔大地震发生已达到活动高潮。预计将持续十到几十年。根据历史地震资料分析, 今后可能沿喜马拉雅带走向发生纵向迁移, 将在喜马拉雅带东段发生更大的地震, 从而使地震高潮达到顶峰而结束, 可能对我国西藏东南、不丹和印度边界产生破坏。另外还可能沿着与喜马拉雅带走向垂直方向向北迁移(即横向迁移), 在几年之内即可在西藏、青海引起破坏性地震, 需要相关省市做好监测预报和防灾工作。 相似文献
3.
2015年尼泊尔Ms81地震构造成因及对青藏高原及邻区未来强震趋势的影响 总被引：2，自引：0，他引：2
2015年尼泊尔大地震的余震分布、震源机制解、震源破裂过程反演结果和喜马拉雅造山带的新生代地质构造特点表明,此次大地震的控震构造是构成印度板块与欧亚板块之间构造边界带的喜马拉雅主逆冲断裂,是印度板块沿该断裂带向欧亚板块之下低角度俯冲过程中导致的一次盲断层型逆冲断裂活动。地震产生的破裂面从北西向东南方向传播,累计长度170km左右,最大倾向滑移量5-7m。该断裂带全新世活动强烈,其上的历史大地震活动频率高、强度大,M≥7.5地震的原地复发平均间隔在500年左右,而在地震活跃阶段分段破裂的平均间隔只有10年左右,并且1800年以来的多次大地震活动显示出从西向东迁移的规律。历史地震活动过程指示,该断裂带上的兴都库什、尼泊尔西部、锡金-不丹和印缅交界区4个空区段的未来大地震危险性较显著,特别是位于此次大地震东部的两个空区。印度板块向北与欧亚板块间的低角度、高强度陆陆俯冲碰撞作用是中国大陆现今地壳变形的主要动力来源。这是中国大陆强震频发的主要地质构造原因,也决定了喜马拉雅与青藏高原及邻区的大地震活动之间明显的时空关联性,主要表现为大地震活跃阶段在时间上的交替出现和大地震沿垂直喜马拉雅造山带的纵向迁移过程。历史地震活动过程和西南地区地震危险性分析成果揭示,在新一轮喜马拉雅大地震活跃形势下,中国大陆将面临更为严峻的大地震危险形势,尤其是青藏高原及邻区晚第四纪活动性显著的区域性构造带或断裂带的潜在强震危险性将比较突出,主要包括：藏南的近南北向裂谷带与北西向右旋走滑断裂带,川滇地块中的安宁河-小江断裂带与大凉山断裂带、南汀河断裂带与畹町断裂带、澜沧-景洪断裂带和滇西北大理-丽江裂陷带,西北地区的西昆仑山前逆冲-褶皱带、阿尔金断裂带和天山的主要逆冲-褶皱变形带等。由于当前中国及西南地区的活动构造调查研究存在的诸多不足限制了对区域大地震危险性更为全面准确的地质评估,并正成为城镇化与重大工程规划建设过程中地壳稳定性评价的“瓶颈”所在。因此,未来的地质调查工作中,建议应紧密结合国家需求,进一步重视新构造与活动构造的调查研究,尽快部署完成重要活动构造区带的活动断裂普查,并重视和加强与邻国的国际合作与交流。 相似文献
4.
印度—欧亚板块碰撞变形区的大地震时空分布特征与迁移规律 总被引：4，自引：4，他引：0
印度板块与欧亚板块在新生代期间的持续碰撞和挤压过程导致亚洲大陆发生了强烈的弥散式板内变形,并形成了一个以贝加尔湖为顶点,以喜马拉雅带为底边的近似三角形的变形区与强震活动区,即新-藏三角区。基于固体刚塑性变形平面结构,结合滑移线场网络模型,对该区历史强震活动的大范围离散式空间分布特点进行了分析解释。结合1505-1976年以来历史强震空间迁移的实例,归纳了该区历史强震活动与地震应变释放从印度板块边界→新-藏地块→两侧大陆的顺序性及定向性迁移特征,并根据对地震空间迁移规律的认识,进一步探讨了区域未来强震危险性问题。结果显示,从2000-2018年间,印度板块边界和新-藏三角区已多次发生M7.9~9.1大地震,但其东、西两侧的区域大陆地区却异常平静,没发生过7级以上大地震。依照区域强震活动的顺序性迁移特点,推测在未来几到几十年,亚洲大陆东部与中部以及喜马拉雅带东段等区域的大地震危险性较大。 相似文献
5.
滨海断裂带是南海北缘的一条大型活动断裂带，其位置靠近我国华南沿海地区。滨海断裂带全长超过1200 km，包括西段（北部湾- 阳江），中段（珠江口）和东段（粤东- 福建）。其西段和东段历史上至少曾发生过4次大地震（M7+），中段目前是一个大地震空区。在经济高速发展和人口高度密集的今天，如果滨海断裂带再次发生大地震并触发海啸，必将对我国华南沿海地区造成灾难性破坏。由于缺乏完整的历史地震记录和针对古地震的钻孔沉积研究，目前尚不清楚滨海断裂带大地震的准确次数、空间分布和复发周期，以及中段大地震空区的主要原因（断层蠕滑或大地震周期较长），因此无法有效评估该断裂带的大地震破裂分段和灾害风险。本研究总结了滨海断裂带的构造特征、重点描述了3次历史大地震及引发的灾害影响，和国际上针对海底大地震的钻探研究经验。根据这些信息，本文建议在断裂带的西段、中断和东段进行大洋钻探，获取穿过断层带的关键沉积和岩石样品，利用沉积古地震方法重建滨海断裂带东段和西段的大地震历史和复发周期，研究断层带的岩石物理性质，揭示滨海断裂中段大地震空区的成因，解析断层分段式破裂的原因，为我国海洋防灾减灾提供重要的科学依据。 相似文献
6.
喜马拉雅造山带是地球上海拔最高、规模最大的陆陆板块俯冲碰撞带在这条长达2 500 km的板块边界上,近年来多次发生破坏性地震,造成大规模的滑坡、房屋倒塌等次生灾害,给人民生命和财产安全造成严重的威胁。分别选取尼泊尔喜马拉雅、喜马拉雅东构造结和喜马拉雅西构造结地区近期发生的3个地震震群作为研究实例,基于中国科学院青藏高原研究所在研究区架设的区域流动地震台站记录的波形资料,对地震的震源位置和震源机制解进行计算。结果表明,在尼泊尔喜马拉雅地区,主喜马拉雅逆冲断裂是大地震的主要发震构造;东构造结地区的地震以逆冲和走滑型为主,表明印度板块向北东方向的逆冲推覆和青藏高原向东南逃逸的侧向挤出是该地区的主要构造背景;西构造结地区中深源地震多发,揭示了高角度大陆深俯冲的几何形态。 相似文献
7.
8.
青藏高原东南缘及邻区近年来地震b值特征 总被引：2，自引：0，他引：2
基于青藏高原东南缘空间数据库及系统建立成果的基础上,综合整理青藏高原东南缘地区的1980—2013年地震信息、地震地质资料及国家基础地理信息,通过Arcgis软件及其脚本编写应用,利用空间模型初步实现了区域内1980—2013年地震活动信息的地统计分析。依据区域地震b值与地壳内部应力分布状态的负相关原理,利用b值进行大面积空间与时间扫描方法对青藏高原东南缘当前应力分布特点进行研究。以2°×2°为单元网格将研究区分为若干区,分别对其进行分时间、分单元b值计算,针对重点低b值区形成时空曲线总结大地震发生前b值曲线的时空规律,并结合之前划出的地震围空区对本区地震危险性进行综合性的中长期预测,结果表明:1汶川地震、芦山地震验证大震发生前后b值时间曲线会有水平—负增长—正增长—负增长—水平的曲线变化;2地震震级越大b值负增长的低值危险区形成时间越早,持续时间越久;3汶川大地震前川北出现大面积低b值异常区;4目前b值低值区持续时间较长的区域有:东喜马拉雅构造结、玉树—甘孜断裂、安宁河断裂—则木河断裂—鲜水河断裂—小江断裂和畹町断裂—南汀河断裂,澜沧断裂—景洪断裂与地震空区危险性预测有较多重叠。 相似文献
9.
全球多数大地震发生在俯冲带地区,然而对于俯冲带地震诱发的滑坡研究并不多见。2015年4月25日尼泊尔廓尔喀县发生了Mw78地震,为喜马拉雅俯冲带近70年来的首次强震,震源机制解表明为低角度逆冲型的俯冲带地震,触发了大量滑坡、崩塌等地震次生灾害。通过遥感解译和现场调查获取2072组地震滑坡信息,揭示滑坡多数分布在海拔1000m~3000m之间,高喜马拉雅与低喜马拉雅的过渡区域,基本沿主中央逆冲断裂断裂(MCT)展布,地势落差大。早期断裂活动频繁,由中、高级变质岩和新生代浅色花岗岩变为古生代沉积岩和少量岩浆岩组成的逆冲岩席,易于发生滑坡、崩塌等地质灾害。滑坡坡度值优势分布区间为35°~40°,与中国西部地区一致,说明地震滑坡坡度分布与大的构造背景相关性较小,可能受局部地形地貌、地层岩性等因素控制。坡向值的优势分布区间为120°~200°,与水平形变场关系紧密。以尼泊尔地震滑坡为例探讨了喜马拉雅俯冲带地震滑坡的特征：滑坡点明显呈相对较宽的矩形区域展布,受深部逆冲推覆构造低倾角的断层破裂面影响较大,滑坡全部位于上盘,由于地震运动的惯性作用,在坡向与上盘逆冲方向一致的斜坡上容易诱发地震滑坡。 相似文献
10.
2015年4月25日,尼泊尔境内发生Ms 8.1级地震,诱发了较大面积的崩塌、滑坡灾害。笔者通过遥感构造解析和野外实地调查取得以下主要认识:（1）中尼边境的喜马拉雅地区活动构造以NWW向挤压逆冲断裂最为显著,从南到北大致可分南、中、北三个带,中带由众多短小、密集的逆冲断裂构成一个网络状断裂带,是这次Ms 8 1级地震的发震断裂;（2）喜山中段NNE—SN向横张断裂将该地区分割成几个东西向块体,吉隆—樟木近南北向断裂带控制了这次强震的余震分布;（3）本次地震引发了至少445处地震崩塌、滑坡、堰塞湖以及融雪形成的泥石流灾害,这些灾害主要分布在NWW向发震断裂的北侧上盘,受发震断裂控制,其中面积超过2.4×104 m2的地震滑坡有30处;（4）中国境内的NNE—SN向深切河谷是滑坡、崩塌等地质灾害的主要发生带,而这些河谷多为公路沿线和村镇居住地,应成为重点防范区。 相似文献
11.
K. N. Khattri 《Journal of Earth System Science》1999,108(2):87-92
Long-term conditional probabilities of occurrence of great earthquakes along the Himalaya plate boundary seismic zone have
been estimated. The chance of occurrence of at least one great earthquake along this seismic zone over a period of 100 years
(beginning the year 1999) is estimated to be about 0.89. The 100-year probability of such an earthquake occurring in the Kashmir
seismic gap is about 0.27, in the central seismic gap about 0.52 and in the Assam gap about 0.21. The 25-year probabilities
of their occurrence in these gaps are 0.07, 0.17, and 0.05 respectively. These probability estimates may be used profitably
to assess the seismic hazard in the Himalaya and the adjoining Ganga plains. 相似文献
12.
The Himalayas are one of very active seismic regions in the world where devastating earthquakes of 1803 Bihar–Nepal, 1897 Shillong, 1905 Kangra, 1934 Bihar–Nepal, 1950 Assam and 2011 Sikkim were reported. Several researchers highlighted central seismic gap based on the stress accumulation in central part of Himalaya and the non-occurrence of earthquake between 1905 Kangra and 1934 Bihar–Nepal. The region has potential of producing great seismic event in the near future. As a result of this seismic gap, all regions which fall adjacent to the active Himalayan region are under high possible seismic hazard due to future earthquakes in the Himalayan region. In this study, the study area of the Lucknow urban centre which lies within 350 km from the central seismic gap has been considered for detailed assessment of seismic hazard. The city of Lucknow also lies close to Lucknow–Faizabad fault having a seismic gap of 350 years. Considering the possible seismic gap in the Himalayan region and also the seismic gap in Lucknow–Faizabad fault, the seismic hazard of Lucknow has been studied based on deterministic and the probabilistic seismic hazard analysis. Results obtained show that the northern and western parts of Lucknow are found to have a peak ground acceleration of 0.11–0.13 g, which is 1.6- to 2.0-fold higher than the seismic hazard compared to the other parts of Lucknow. 相似文献
13.
A shallow-focus damaging earthquake of magnitude 6.9?Mw struck the Sikkim Himalaya, north-east India, on 18 September 2011 at 12:40:48 UTC (06:10:48PM IST). The epicentre was located north-west of Chungthang on Indo-Nepal border of Sikkim Himalaya. The earthquake was widely felt in northern India and caused widespread damage to poorly built and framed structures in Sikkim region, northern Bihar, eastern Nepal, southern Bhutan and part of Tibet adjoining Sikkim Himalaya. A lot of secondary effects in the form of landslides, rockfalls and landslide lake outburst flood were caused due to strong shaking effect of the earthquake. Maximum intensity IX according to the European Macroseismic Scale-98 was observed in the meizoseismal zone surrounding Chungthang village. Asymmetrical distribution and heterogeneous damage pattern demonstrate intensity attenuation characteristics of the region. Although the regional tectonic framework of Sikkim region indicates compressional thrust tectonics regime, according to CMT fault-plane solution this earthquake involved predominantly strike-slip motion on a steep fault. Unlike Nepal and north-west Himalaya where microseismicity and large earthquakes indicate thrust mechanism, this Sikkim earthquake suggests that strike-slip principal component may imply transcurrent deformation. 相似文献
14.
The Himalayas has experienced varying rates of earthquake occurrence in the past in its seismo-tectonically distinguished segments which may be attributed to different physical processes of accumulation of stress and its release, and due diligence is required for its inclusion for working out the seismic hazard. The present paper intends to revisit the various earthquake occurrence models applied to Himalayas and examines it in the light of recent damaging earthquakes in Himalayan belt. Due to discordant seismicity of Himalayas, three types of regions have been considered to estimate larger return period events. The regions selected are (1) the North-West Himalayan Fold and Thrust Belt which is seismically very active, (2) the Garhwal Himalaya which has never experienced large earthquake although sufficient stress exists and (3) the Nepal region which is very seismically active region due to unlocked rupture and frequently experienced large earthquake events. The seismicity parameters have been revisited using two earthquake recurrence models namely constant seismicity and constant moment release. For constant moment release model, the strain rates have been derived from global strain rate model and are converted into seismic moment of earthquake events considering the geometry of the finite source and the rates being consumed fully by the contemporary seismicity. Probability of earthquake occurrence with time has been estimated for each region using both models and compared assuming Poissonian distribution. The results show that seismicity for North-West region is observed to be relatively less when estimated using constant seismicity model which implies that either the occupied accumulated stress is not being unconfined in the form of earthquakes or the compiled earthquake catalogue is insufficient. Similar trend has been observed for seismic gap area but with lesser difference reported from both methods. However, for the Nepal region, the estimated seismicity by the two methods has been found to be relatively less when estimated using constant moment release model which implies that in the Nepal region, accumulated strain is releasing in the form of large earthquake occurrence event. The partial release in second event of May 2015 of similar size shows that the physical process is trying to release the energy with large earthquake event. If it would have been in other regions like that of seismic gap region, the fault may not have released the energy and may be inviting even bigger event in future. It is, therefore, necessary to look into the seismicity from strain rates also for its due interpretation in terms of predicting the seismic hazard in various segments of Himalayas. 相似文献
15.
M. R. Pandey R. P. Tandukar J. P. Avouac J. Vergne Th. Hritier 《Journal of Asian Earth Sciences》1999,17(5-6)
The National Seismological Network of Nepal consists of 17 short period seismic stations operated since 1994. It provides an exceptional view of the microseismic activity over nearly one third of the Himalayan arc, including the only segment, between longitudes 78°E and 85°E, that has not produced any M>8 earthquakes over the last century. It shows a belt of seismicity that follows approximately the front of the Higher Himalaya with most of the seismic moment being released at depths between 10 and 20 km. This belt of seismicity is interpreted to reflect interseismic stress accumulation in the upper crust associated with creep in the lower crust beneath the Higher Himalaya. The seismic activity is more intense around 82°E in Far-Western Nepal and around 87°E in Eastern Nepal. Western Nepal, between 82.5 and 85°E, is characterized by a particularly low level of seismic activity. We propose that these lateral variations are related to segmentation of the Main Himalayan Thrust Fault. The major junctions between the different segments would thus lie at about 87°E and 82°E with possibly an intermediate one at about 85°E. These junctions seem to coincide with some of the active normal faults in Southern Tibet. Lateral variation of seismic activity is also found to correlate with lateral variations of geological structures suggesting that segmentation is a long-lived feature. We infer four 250–400 km long segments that could produce earthquakes comparable to the M=8.4 Bihar–Nepal earthquake that struck eastern Nepal in 1934. Assuming the model of the characteristic earthquake, the recurrence interval between two such earthquakes on a given segment is between 130 and 260 years. 相似文献
16.
Arjun Pandey Ishwar Singh Rajeeb Lochan Mishra Priyanka Singh Rao Hari B Srivastava R Jayangondaperumal 《Journal of Earth System Science》2018,127(5):66
The Assam Seismic Gap has witnessed a long seismic quiescence since the \({ Mw}{\sim }8.4\) great Assam earthquake of AD 1950. Owing to its improper connectivity over the last decades, this segment of the Himalaya has long remained inadequately explored by geoscientists. Recent geodetic measurements in the eastern Himalaya using GPS document a discrepancy between the geologic and geodetic convergence rates. West to east increase in convergence rate added with shorter time span earthquakes like the 1697 Sadiya, 1714 (\({ Mw}{\sim }8\)) Bhutan and 1950 (\({ Mw}{\sim } 8.4\)) Tibet–Assam, makes this discrepancy more composite and crucial in terms of seismic hazard assessment. To understand the scenario of palaeoearthquake surface rupturing and deformation of youngest landforms between the meizoseismal areas of \({ Mw}{\sim }8.1\) 1934 and 1950 earthquakes, the area between the Manas and Dhanshiri Rivers along the Himalayan Frontal Thrust (HFT) was traversed. The general deformation pattern reflects north-dipping thrust faults. However, back facing scarps were also observed in conjugation to the discontinuous scarps along the frontal thrust. Preliminary mapping along with the published literature suggests that, in the eastern Himalayan front the deformation is taking place largely by the thrust sheet translation without producing a prominent fault-related folds, unlike that of the central and western Himalayas. 相似文献
17.
《International Geology Review》2012,54(18):2313-2327
ABSTRACTDuoqing Co is a 60 km2 outflow lake in the N-trending Pagri graben, located at the southern end of the Yadong-Gulu rift in Tibet. The water in this lake suddenly disappeared between November 2015 and April 2016, closely following the Ms 8.1 (Mw 7.8) Nepal earthquake in April 2015. Both, geomorphological and remote sensing data indicate the existence of blind faults striking NNE along the east boundary of Duoqing Co lake. There were also several nearly NE-trending extensional cracks preserved in the dried lakebed, apparently formed in response to creeping deformation of the underlying rock. Based on field studies and analysis of meteorological and remote sensing data, it is suggested that this phenomenon cannot be explained by evaporation linked to climate change nor can it be related to human activity. Instead, it is considered that the lake water drained through the extensional cracks formed in the lakebed as it responded to the far-field effects of the 2015 Nepal earthquake. It is proposed that a shift in regional tectonics occurred as a result of the Nepal earthquake, causing a sharp increase in stress accumulation along the seismically locked Bhutan–Sikkim zone on the Main Himalayan Thrust (MHT) fault, which was accommodated by the extension of the Pagri graben in the southern Yadong-Gulu rift. It is believed that the crust may have reached a critical stress-state that resulted in strain hardening and brittle failure throughout the region along the Bhutan–Sikkim segment of the MHT. If so, considering the high potential for tectonic activity along the segment of the MHT, it may be worth paying attention to deformational changes and potential geomorphological precursors that might appear in the seismically locked Bhutan–Sikkim gap to predict future earthquakes. 相似文献
18.
Himalayan orogenic belt is the highest and largest continental collision and subduction zone on the Earth. The Himalayan orogenic belt has produced frequent large earthquakes and caused several geohazards due to landslides and housing collapse, having an impact on the safety of life and property along a length of over 2500 km. Here we took three earthquake clusters as examples, which occurred at Nepal Himalaya, eastern Himalayan syntaxis and western Himalayan syntaxis, respectively. Here we calculated the earthquake locations and fault plane solutions based on the waveform data recorded by seismic stations deployed in source areas by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences. We found that at the Nepal Himalayan, the Main Himalayan Thrust is the major tectonic structure for large earthquakes to occur. At the eastern Himalayan syntaxis, most earthquakes are of the reverse or strike-slip faulting. The major tectonic feature is the combination of the NE-dipping thrust with the southeastern escape of the Tibetan plateau. At the western Himalayan syntaxis, intermediate-depth earthquakes are active. These observations reveal the geometry of the deep subduction of the continental plate with steep dipping angle. 相似文献