共查询到16条相似文献，搜索用时 132 毫秒
1.
礼县 -罗家堡断裂带晚更新世以来有过明显活动。在礼县—罗家堡段和天水镇—街子口段直接错断全新世地层。断裂沿线地表陡坎发育 ,水系被左旋位错。结合沿该断裂带广泛分布的地震滑坡、砂土液化等 ,认为礼县 -罗家堡断裂带是 1654年天水南 8级地震的发震构造。该断裂晚更新世以来的平均水平位错速率为 0 95mm/a ,平均垂直位移速率为 0 35mm/a ,垂直位移速率约为水平位移速率的 1/ 3。这个比值与一次断裂突发性垂直位错量 ( 1 9m)与水平位错量 ( 5 2m)的比值基本吻合 相似文献
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简要回顾了1654年天水南8级地震的研究历史，结合原有史料和新补充调查所获得的资料，核定了各破坏点的地震烈度，进而改绘了地震等震线图，其长轴方向为NE向。此次地震除造成大范围的城垣毁坏、房屋倒塌和人员伤亡之外，滑坡、山崩和堰塞湖等地震地质灾害也非常严重。其极震区位于礼县以东的西汉水河谷永兴镇—罗家堡—天水镇一带。该区发育了全新世活动的礼县—罗家堡断裂，其性质为左旋走滑兼正断。根据最新调查结果，该断裂沿礼县—盐关—罗家堡一带保存了地震陡坎、纹沟左旋和地震沟槽等地震地表破裂带形迹，其地理位置与历史资料考证所确定的极震区范围一致，印证了二者结论的可靠性和合理性。 相似文献
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1654年礼县8级地震的发震区地处新构造活动强烈的青藏高原东北缘,位于南北地震带中北段,发育多条活动断裂。礼县8级地震发生在黄土覆盖区,距今约370年,受自然侵蚀与人类活动的影响,其地表破裂带和次生灾害现在已经难以分辨。为此,文章收集整理了1970年以来的地震台网和流动台网观测资料,基于地震层析成像方法,经过联合反演计算,研究1654年礼县8级地震的发震构造。研究根据岷县—礼县—两当一线的小震活动分布,推测存在"岷县—礼县—两当断裂",可能是1654年礼县8级地震的发震断裂,但仍需野外地质工作的进一步研究。 相似文献
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利用GIS方法研究南北地震带和中央造山带交汇区活动断裂与地震的关系 总被引：3，自引：1，他引：2
基于地理信息系统(GIS)技术研究南北地震带和中央造山带交汇区断裂带分布与地震活动的关系,对区内16条主要断裂带,以25km为缓冲区宽度,进行叠加,分析各断裂带的地震活动性及其特征.结果表明,主要的发震断裂有西秦岭北缘断裂的西段、礼县-罗家堡断裂西南段以及临潭-宕昌断裂的东南段、文县断裂西南段、虎牙断裂和雪山断裂;虎牙断裂和雪山断裂地震活动性最强,其次是塔藏断裂、礼县-罗家堡断裂以及光盖山-迭山北麓断裂;按震源深度可将研究区划分为4个区域,区内的震源深度由北向南逐渐加大,震源深度剖面图反映了断层的几何形态和力学性质,进一步揭示出了青藏高原向东挤压、物质向东向南逃逸的运动模式. 相似文献
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阿拉善地块南缘地处青藏高原东北缘地壳扩展前锋带的北侧，对该地区活动断裂晚第四纪的运动性质、滑动速率等开展研究，有助于理解阿拉善地块的晚第四纪构造变形特征及其对青藏高原向N扩展的响应。文中结合遥感影像解译与野外地质地貌考察，对阿拉善地块南缘的北大山断裂进行了分段和活动性研究。结果表明，北大山断裂左旋走滑断错晚第四纪洪积扇和阶地等地貌，形成显著的位错阶地坎、冲沟以及断层陡坎。通过对断错地貌线等标志的测量、复原、统计分析等，发现断裂的地貌位移值分布于3～20m,发育新鲜断层自由面的断层陡坎和左旋错动的纹沟指示了断层的最新一次活动。基于同期洪积扇年龄估算得到北大山断裂晚更新世以来的左旋滑动速率为0.3～0.6mm/a。北大山断裂的运动学特征与区域NE向应力场一致，可能受到了青藏高原NE向扩展的影响。 相似文献
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位于南北地震带中北段的甘东南地区,其构造变形和构造活动特征与青藏高原向北东方向的扩展密切相关,该地区复杂的构造几何形态主要受控于东昆仑断裂和西秦岭北缘断裂,区域新构造运动主要动力来源于青藏高原向北东的扩展.近年来,甘东南地区中强地震频发,本文主要通过对该地区构造活动特征、历史地震等资料的综合分析讨论,结合地球物理、地震学和野外调查等资料,认为青藏高原东北部东昆仑断裂的向北挤压和向东的运动是该地区构造应力集中的主要原因,也是该地区中强地震的主要孕震环境和机制,而西秦岭北缘断裂的走滑及向南北两侧逆冲“花状构造”是临潭—宕昌断裂带上中强地震频繁发生的一个重要动力因素.2013年7月22日发生在甘肃岷县—漳县的MS6.6级地震正好位于临潭—宕昌断裂带中东段上,是该断裂分段不均匀活动的结果. 相似文献
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根据历史地震资料考证、现场考察与综合分析，1765年5月1日发生在临洮南的一次中强破坏性地震其极震区位于卓尼、康乐交界的洮河连麓盆地附近的柳林、宗石一带，其名称应修改为卓尼-康乐地震，震级约5 1/2~6级，震中烈度可达Ⅷ度，极震区长轴方向大致与该区西秦岭北缘断裂带西段的锅麻滩断裂段东端相吻合。根据野外实地调查，锅麻滩断裂在极震区附近存在新活动的地质地貌现象，出露的断层剖面揭示出以左旋走滑为主兼具向北倾的正断特征，宏观地貌上沿断裂保留有断层陡坎、冲沟左旋位错等地貌标志。结合该区域构造应力场分析，本次卓尼-康乐地震发生在锅麻滩断裂段与漳县-黄香沟断裂段之间的左阶拉分区，是受区域应力影响引起断裂带在交汇部位与端点处应力集中所致。综合分析认为，锅麻滩断裂带东端是此次地震的发震构造。 相似文献
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《地震地质》2020,(2)
通常认为甘肃北山是构造稳定区,不发育活动断裂,近年来新发现的俄博庙活动断裂挑战了这一传统认识,深入研究该断裂的新活动特征和活动速率,对于重新认识北山地区的新构造活动以及青藏高原和阿拉善块体的相互作用等问题具有重要意义。文中基于卫星影像解译、探槽开挖、差分GPS和无人机摄影测量、光释光测年等成熟的活动构造研究方法,定量研究了俄博庙断裂的新活动特征,得到以下认识:首先,文中完善了俄博庙断裂的几何展布,将断裂长度由约20km延长至45km,根据破裂长度与震级的经验关系推断俄博庙断裂具有发生7级地震的能力;其次,查明了断层陡坎的形态和成因,发现正向陡坎和反向陡坎交替发育,反向陡坎的高度为(0.22±0. 02)～(1.32±0. 1) m,正向陡坎的高度为(0.33±0. 1)～(0.64±0. 1) m,反向陡坎受由南向北低角度逆冲的断层控制,断层倾角为23°～86°,正向陡坎受倾向S的高角度正断层控制,断层倾角为60°～81°;另外,断层的左旋走滑比倾滑更显著,西段19条冲沟的左旋位移为(3.8±0. 5)～(105±25) m,根据其中最典型的一条冲沟的阶地陡坎的左旋位移量(16.7±0. 5) m和上阶地年龄(11.2±1. 5) ka,得到俄博庙断裂晚更新世末以来的左旋滑动速率为(1.52±0. 25) mm/a。晚新生代以来,在青藏高原NE向扩展的构造背景下,俄博庙断裂的新活动特征可能响应了青藏高原与阿拉善块体之间的相对剪切分量。 相似文献
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祁连山北缘佛洞庙-红崖子断裂古地震特征初步研究 总被引：4，自引：1，他引：3
佛洞庙-红崖子断裂位于祁连山北缘断裂带中部,是祁连山与河西走廊之间的一条重要边界断裂,断裂全长约110km,总体走向北西西,该断裂为一条全新世活动的逆-左旋走滑断裂,断裂活动形成了一系列陡坎、断层崖以及冲沟和阶地左旋等断错地貌.本文通过3个探槽剖面对发生在该断裂上的古地震事件进行了分析,可确定地震事件2次,事件Ⅰ为历史地震,发生在距今400年前,为1609年红崖堡71/4级地震;事件Ⅱ的年代为距今（6.3±0.6）ka B.P.和（7.4±0.4）ka B.P.之间.同时结合前人的一些研究资料,对古地震的复发模式和间隔进行了初步讨论. 相似文献
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南北地震带是中国大陆的一条主要活动地震带, 20世纪以来有很多大地震集中发生在这条地震带上。为了进一步探讨南北地震带地震活动强度变化的规律并对其进行中期预测,在研究了南北地震带逐年最大地震强度演化特征及其机理的基础上,建立了南北地震带地震强度序列变化的一种模式,建模中采用了人工神经网络技术,并提出了一种简易实用的能够获得较隹预测效果的确定神经网络输入窗口大小的方法。结果表明: 南北地震带的地震活动具有强弱分期轮回的特征; 用人工神经网络建模的预测结果与实际资料的对比检验中误差较小,因而该模型可作为南北地震带地震活动强度变化的预测模型。 相似文献
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黑龙江省萝北地区是东北现代地震活动最为活跃的地区之一，中小地震密集成带分布，曾于1963年发生5.8级地震，但其发震构造一直不清楚。精定位后的震中分布图像和震源机制解研究结果表明，现代地震总体呈NEE方向密集分布于黑龙江小兴安岭山前太平沟一带，地震类型以右旋走滑为主。通过高分辨率的卫星影像解译结果发现太平沟一带发育一条长约25km，走向约N70°E的线性异常带。野外地表调查发现该线性异常表现为断续分布的断裂陡坎、冲沟位错和滑坡。陡坎走向约N65°E-N75°E，倾向SE，高约1.0-2.5m；滑坡发育有典型的弧形圈椅构造，规模大小不等，多与断裂陡坎伴生。综合现代地震活动图像、卫星影像解译、野外地质调查结果，特别是结合2013年11月和2014年2月该地区的2次小震活动及现代地震活动的空间图像分布特征，研究认为太平沟断裂属于依兰-伊通断裂带的分支断裂，晚第四纪期间曾经强烈活动，具备中强地震的发震能力，可能是萝北1963年5.8级地震的发震构造。 相似文献
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关于岷江断裂若干问题的讨论 总被引：20，自引：2，他引：20
本文在野外观察的基础上，结合年代学样品测定资料，讨论了岷江断裂的几何特征、晚第四纪活动性以及潜在地震能力。笔者认为，岷江断裂并不是一条单一的南北向断裂，而是由多条北东－北北东向次级断层左阶羽列而成。由于岷江断裂总体延伸方向的差异，可以把它分为南、北、中三段。中段控制第四纪盆地，并具有晚第四纪活动性。进一步的研究认为，断理解几何特征导致的断层分段对断裂的潜在地震能力具有控制作用。 相似文献
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卡兹克阿尔特断裂带活动特征 总被引：7，自引：0，他引：7
卡兹克阿尔特断裂带是帕米尔和天山新生代造山带间一个重要的活动构造边界,通过对其活动构造特征的详细地质调查和大比例尺填图,可将卡兹克阿尔特断裂带进一步划分为吉勒格由特断裂带、乌恰地震断裂带和木什断裂带3段.吉勒格由特断裂带的地表破裂为一系列的断层陡坎和偏转的冲积扇,经过别尔托阔依河出山口处时,切割了T1至T3堆积阶地.断裂带在T1、T2和T3阶地的断层陡坎高度分别为0.67m、3.90m和36.50m.对采自T2阶地顶部和底部的粉砂样品进行光释光测年,测定的初步结果分别为8900aBP和10500aBP,因此对T3、T2阶地以来的滑动速率估计分别约为3.5mm/a、0.8mm/a.断裂的前缘开挖的探槽揭示出全新世以来有4次古地震活动.乌恰地震带主要切割克兹勒苏河的T3阶地后缘,沿断裂带分布有大小不等的断塞塘和断层陡坎.1985年8月23日在乌恰地震带上发生Ms7.4地震,地震最大位错为1.5m.根据断层陡坎计算出断裂的滑动速率约为0.54mm/a.卡帕河的东岸探槽同样揭示出有4次古地震活动.在乌恰地震带的东端,木什断裂带地表长度约6km,由数十条左阶排列的反向断层陡坎(坡向北)组成,沿这些断坎多处可见冲沟被断错,横跨断层陡坎的探槽揭示出3次古地震活动. 相似文献
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Abstract The Shinanogawa Seismic Belt in the Northern Fossa Magna, Honshu Island, Japan, extends along the Shinano River, bounding the Eurasian Plate and the Okhotsk Plate. The geopressured hydrothermal system occurs widely in the Northern Fossa Magna region. Many destructive earthquakes are related to the activity of this system in the Shinanogawa Seismic Belt. Expulsion of a geopressured hydrothermal system and rising from depth along an active fault triggers the occurrence of an earthquake and opens the fault as a pathway. Anomalous areas in temperature, electrical conductivity and Cl– concentration of groundwater trend north–east in a linear distribution, and convincingly demonstrate the presence of a buried active fault at the epicentral area of the destructive earthquake in the Shinanogawa Seismic Belt. The distribution of the major axis of the anomalous area in groundwater temperature shows a strong positive relationship with earthquake magnitude, which means that the distribution of this area may indicate the scale of earthquake fault. The linearly anomalous areas in groundwater temperature, resulting from the percolation of a geopressured hydrothermal system, that have no record of previous destructive earthquake are predicted to be areas where destructive earthquakes could occur in the future. Four potential earthquake areas are proposed and discussed in this paper, based on re-examination of active faults and seismicity in the Shinanogawa Seismic Belt. 相似文献
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NEW ACTIVITY CHARACTERISTICS AND SLIP RATE OF THE EBOMIAO FAULT IN THE SOUTHERN MARGIN OF BEISHAN,GANSU PROVINCE 
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下载免费PDF全文 ZHANG Bo HE Wen-gui LIU Bing-xu GAO Xiao-dong PANG Wei WANG Ai-guo YUAN Dao-yang 《地震地质》1979,42(2):455-471
The Ebomiao Fault is a newly discovered active fault near the block boundary between the Tibetan plateau and the Alashan Block. This fault locates in the southern margin of the Beishan Mountain, which is generally considered to be a tectonically inactive zone, and active fault and earthquake are never expected to emerge, so the discovery of this active fault challenges the traditional thoughts. As a result, studying the new activity of this fault would shed new light on the neotectonic evolution of the Beishan Mountain and tectonic interaction effects between the Tibetan plateau and the Alashan Block. Based on some mature and traditional research methods of active tectonics such as satellite image interpretation, trenches excavation, differential GPS measurement, Unmanned Aircraft Vehicle Photogrammetry(UAVP), and Optical Stimulated Luminescence(OSL)dating, we quantitatively study the new activity features of the Ebomiao Fault.
Through this study, we complete the fault geometry of the Ebomiao Fault and extend the fault eastward by 25km on the basis of the 20km-fault trace identified previously, the total length of the fault is extened to 45km, which is capable of generating magnitude 7 earthquake calculated from the empirical relationships between earthquake magnitude and fault length. The Ebomiao Fault is manifested as several segments of linear scarps on the land surface, the scarps are characterized by poor continuity because of seasonal flood erosion. Linear scarps are either north- or south-facing scarps that emerge intermittently. Fourteen differential GPS profiles show that the height of the north-facing scarps ranges from (0.22±0.02)m to (1.32±0.1)m, and seven differential GPS profiles show the height of south-facing scarps ranging from (0.33±0.1)m to (0.64±0.1)m. To clarify the causes of the linear scarps with opposite-facing directions, we dug seven trenches across these scarps, the trench profiles show that the south-dipping reverse faults dominate the north-facing scarps, the dipping angles range from 23° to 86°. However, the south-facing scarps are controlled by south-dipping normal faults with dipping angles spanning from 60° to 81°.
The Ebomiao Fault is dominated by left-lateral strike-slip activity, with a small amount of vertical-slip component. From the submeter-resolution digital elevation models(DEM)constructed by UAVP, the measured left-lateral displacement of 19 gullies in the western segment of the Ebomiao Fault are(3.8±0.5)~(105±25)m, while the height of the north-facing scarps on this segment are(0.22±0.02)~(1.32±0.10)m(L3-L7), the left-lateral displacement is much larger than the scarp height. In this segment, there are three gullies preserving typical left-lateral offsets, one gully among them preserves two levels of alluvial terraces, the terrace riser between the upper terrace and the lower terrace is clear and shows horizontal offset. Based on high-resolution DEM interpretation and displacement restoration by LaDiCaoz software, the left-lateral displacement of the terrace riser is measured to be(16.7±0.5)m. The formation time of the terrace riser is approximated by the OSL age of the upper terrace, which is (11.2±1.5)ka BP at (0.68±0.03)m beneath the surface, and(11.4±0.6)ka at (0.89±0.03)m beneath the surface, the OSL age (11.2±1.5)ka BP at (0.68±0.03)m beneath the surface is more close to the formation time of the upper terrace because of a nearer distance to sediment contact between alluvial fan and eolian sand silt. Taking the (16.7±0.5)m left-lateral displacement of the terrace riser and the upper terrace age (11.2±1.5)ka, we calculate a left-lateral strike-slip rate of(1.52±0.25)mm/a for the Ebomiao Fault. The main source for the slip rate error is that the terrace risers on both walls of the fault are not definitely corresponded. The north wall of the fault is covered by eolian sand, we can only presume the location of terrace riser by geomorphic analysis. In addition, the samples used to calculate slip rate before were collected from the aeolian sand deposits on the north side of the fault, they are not sediments of the fan terraces, so they could not accurately define the formation age of the upper terrace. This study dates the upper terrace directly on the south wall of the fault.
Since the late Cenozoic, the new activity of the Ebomiao Fault may have responded to the shear component of the relative movement between the Tibetan plateau and the Alashan Block under the macroscopic geological background of the northeastern-expanding of the Tibetan plateau. The north-facing fault scarps are dominated by south-dipping low-angle reverse faults, the emergence of this kind of faults(faults overthrusting from the Jinta Basin to the Beishan Mountain)suggests the far-field effect of block convergence between Tibetan plateau and Alashan Block, which results in the relative compression and crustal shortening. As for whether the Ebomiao Fault and Qilianshan thrust system are connected in the deep, more work is needed. 相似文献
Through this study, we complete the fault geometry of the Ebomiao Fault and extend the fault eastward by 25km on the basis of the 20km-fault trace identified previously, the total length of the fault is extened to 45km, which is capable of generating magnitude 7 earthquake calculated from the empirical relationships between earthquake magnitude and fault length. The Ebomiao Fault is manifested as several segments of linear scarps on the land surface, the scarps are characterized by poor continuity because of seasonal flood erosion. Linear scarps are either north- or south-facing scarps that emerge intermittently. Fourteen differential GPS profiles show that the height of the north-facing scarps ranges from (0.22±0.02)m to (1.32±0.1)m, and seven differential GPS profiles show the height of south-facing scarps ranging from (0.33±0.1)m to (0.64±0.1)m. To clarify the causes of the linear scarps with opposite-facing directions, we dug seven trenches across these scarps, the trench profiles show that the south-dipping reverse faults dominate the north-facing scarps, the dipping angles range from 23° to 86°. However, the south-facing scarps are controlled by south-dipping normal faults with dipping angles spanning from 60° to 81°.
The Ebomiao Fault is dominated by left-lateral strike-slip activity, with a small amount of vertical-slip component. From the submeter-resolution digital elevation models(DEM)constructed by UAVP, the measured left-lateral displacement of 19 gullies in the western segment of the Ebomiao Fault are(3.8±0.5)~(105±25)m, while the height of the north-facing scarps on this segment are(0.22±0.02)~(1.32±0.10)m(L3-L7), the left-lateral displacement is much larger than the scarp height. In this segment, there are three gullies preserving typical left-lateral offsets, one gully among them preserves two levels of alluvial terraces, the terrace riser between the upper terrace and the lower terrace is clear and shows horizontal offset. Based on high-resolution DEM interpretation and displacement restoration by LaDiCaoz software, the left-lateral displacement of the terrace riser is measured to be(16.7±0.5)m. The formation time of the terrace riser is approximated by the OSL age of the upper terrace, which is (11.2±1.5)ka BP at (0.68±0.03)m beneath the surface, and(11.4±0.6)ka at (0.89±0.03)m beneath the surface, the OSL age (11.2±1.5)ka BP at (0.68±0.03)m beneath the surface is more close to the formation time of the upper terrace because of a nearer distance to sediment contact between alluvial fan and eolian sand silt. Taking the (16.7±0.5)m left-lateral displacement of the terrace riser and the upper terrace age (11.2±1.5)ka, we calculate a left-lateral strike-slip rate of(1.52±0.25)mm/a for the Ebomiao Fault. The main source for the slip rate error is that the terrace risers on both walls of the fault are not definitely corresponded. The north wall of the fault is covered by eolian sand, we can only presume the location of terrace riser by geomorphic analysis. In addition, the samples used to calculate slip rate before were collected from the aeolian sand deposits on the north side of the fault, they are not sediments of the fan terraces, so they could not accurately define the formation age of the upper terrace. This study dates the upper terrace directly on the south wall of the fault.
Since the late Cenozoic, the new activity of the Ebomiao Fault may have responded to the shear component of the relative movement between the Tibetan plateau and the Alashan Block under the macroscopic geological background of the northeastern-expanding of the Tibetan plateau. The north-facing fault scarps are dominated by south-dipping low-angle reverse faults, the emergence of this kind of faults(faults overthrusting from the Jinta Basin to the Beishan Mountain)suggests the far-field effect of block convergence between Tibetan plateau and Alashan Block, which results in the relative compression and crustal shortening. As for whether the Ebomiao Fault and Qilianshan thrust system are connected in the deep, more work is needed. 相似文献