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在塔吉克斯坦—新疆３５条全新世活断层中,２４条发生过２次以上古地震,发生７．０级以上古地震的平均复现期为３２４２±５５年。阿尔金活动断裂带是最活跃的断层,其古地震平均复现期为４１７±５５年。将每条活断层的古地震复现期与最后一次７．０级以上地震发生的时间相比,巴里坤纸房—秦大汉活断层、托里活断层、沙湾独山子—安集海活断层、霍尔果斯活断层及吐鲁番盆地中央活动断裂带为预警式活断层,有发生７．０级以上地震的危险,即未来北天山地震带与西准噶尔—阿尔泰地震带是有强震危险的地震带。这两条地震带的古地震复现期一般比南天山地震带与帕米尔—阿尔金山地震带长。４条地震带的古地震平均复现期为５８９±２年。塔吉克斯坦—新疆古地震的平均复现期为１３９±１年 相似文献
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地震构造系潜在震源区的蕴震及发震构造,也是地震所产生的断层和形变带,受活断层及活动褶皱控制。 新疆主要的地震构造位于印度板块和欧亚板块相碰撞的喜马拉雅碰撞带的后陆,多在碰撞期后形成。这些碰撞期后构造就是新疆主要的地震构造,分布于羌塘板块、冈底斯板块、哈萨克斯坦板块和西伯利亚板块相互碰撞地段,即塔里木盆地南北缘、准噶尔盆地南缘及东北缘、伊犁盆地两侧、塔什库尔干谷地、布伦口各地以及鲸鱼湖盆地南缘。 从新疆历史地震断层或形变带的时间及空间分布来看,其活动顺序为:1716年特克斯活断层→1812年喀什河活断层→1842年巴里坤洛包泉活断层→1895年塔什库尔干活断层→1902年托特拱拜孜—阿尔帕勒克活断层→1906年准噶尔盆地南缘活断层→1914年鄯善碱泉子活断层→1924年阿尔金活断层→1931年可可托海—二台活断层→1985年卡兹克阿尔特活断层,反映了地震构造活动的新生性及迁移性。7—8级地震迁移距离为120—1340km,平均为640km。这些地震构造一般都发生过多次古地震,其平均复现期为千年左右。由布伦口活断层、策勒活断层、木孜塔格—鲸鱼湖活断层及霍尔果斯—吐谷里活断层上古地震断层的发现,拜城、库尔勒、吐鲁番和木垒古地震遗迹的展布,以及地震迁移规律等表明,今后十年北天山、南天山 相似文献
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新疆独山子山前活断层和活褶皱及古地震研究 总被引：2，自引：0，他引：2
本文初步研究了新疆独山子山前活断层、活褶皱构造。这些表层构造有着不同性质的地表变形,是多次古地震活动的反映。文中将这些古地震遗迹分为四期,并计算了该断层带的地震复发周期和平均位移速率。 相似文献
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富蕴地震断裂带位于新疆北部阿尔泰地区,它继承性地发展了可可托海——二台断裂,于1931年8月发生富蕴8.0级地震。断裂带内古地震及断层活动遗迹保存良好,对地震研究。有着极其重要的价值,因此引起了中外学者的关注。目前,人们试图利用地层年代配合野外证据,研究和推断断层活动及古地震重复周期。本文将利用所获得的~(14)C 年代数据,确定该地区全新世地层的年代,并对全新世以来,断层的活动年代进行一些粗略的探讨,为研究断裂的重复周期提供一些资料。 相似文献
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1984年,作者对阿尔金北缘断裂带东段(甘肃省境内部分)进行了以古地震为主要内容的活断层考查和研究。野外工作历时两个半月,共测量断层崖剖面33个,釆得~(14)C样品20个,并且开挖了探槽,在古地震、断层几何、断层活动方式、活动强度以及滑动速率等方面获得 相似文献
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托里活断层、达尔布特活断层、独山子—安集海活断层及霍尔果斯—卡子湾活断层是塔城地区主要的全新世活断层，均有过多次古地震活动。自１９７７年以来，４级以上地震活动的空区在裕民县西北。据活断层古地震活动复现期及地震活动围空特点分析，今后１０年北天山或塔城西北可能有发生６级左右地震的危险。 相似文献
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通过对地震断层陡坎演为过程的分析，应用均匀物质扩散理论建立地震断层陡坎的形态方程，推断古地震断层陡坎的年龄，从而确定古地震事件的期次及年代。用该方法对二台活断层古地震断层陡坎进行计算，所得结果与用其它方法确定的古地震事件的期次及年代对应较好。 相似文献
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本文概述了阿尔金北缘断裂带东北段(甘肃境内)的地质背景和新构造运动,讨论了断层特性、断层几何学、形变图象及一些特殊走滑运动地貌等问题。根据第四纪后期不同时代的地貌单元被水平左旋错移的幅度,结合C~(14)年代测定,求出5个不同时代至今的平均滑动速率,并分析了断层活动的一些时空特点。文章还探讨了古地震现象,现代地震活动与断裂的关系及地震危险性,较详细地研究了新发现的芦草沟古地震形变带。 相似文献
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Late Pleistocene and Holocene slip rate of the Northern Wadi Araba fault, Dead Sea Transform, Jordan
Tina M. Niemi Hongwei Zhang Mohammad Atallah J. Bruce J. Harrison 《Journal of Seismology》2001,5(3):449-474
The Wadi Araba Valley is a morphotectonic depression along part of theDead Sea Transform (DST) plate boundary that separates the Arabian plateon the east from the Sinai subplate on the west. The Wadi Araba fault(WAF) is the main strike-slip faults one of between the Gulf of Aqaba and the E-Wtrending Khunayzira (Amatzayahu) fault that bounds the southern end ofthe Dead Sea. Just south of the Dead Sea, the WAF cuts across severalgenerations of alluvial fans that formed on tributaries to the Wadi Dahalafter the regression of Late Pleistocene Lake Lisan ca. 15 ka. Geomorphicand stratigraphic evidence of active faulting, including left-laterally offsetstream channels and alluvial-fan surfaces, yielded fault slip-rate data for thenorthern segment of WAF. Typical cumulative displacements of 54 m,39 m, and 22.5 m of stream channels and alluvial-fan surfaces acrossthe fault were measured from detailed geologic and topographic mapping.The 54 m offset of the oldest alluvial-fan surface (Q
f1
) occurredafter the final lowering of Lake Lisan (16–15 ka) and before 11 ka yieldinga slip-rate range of 3.4 mm/yr to 4.9 mm/yr. Based on radiocarbonages of charcoal and landsnail shell samples from the buried Q
f2
alluvial-fan deposits exposed in trenches excavated across the fault, the39 m and 22.5 m offsets occurred after 9 ka and 5.8 ka, respectively. These data yield a slip-rate range between 3.9 mm/yr and 6.0 mm/yr.The small variability in these slip-rate estimates for different time periodssuggests that the northern Wadi Araba fault has maintained a relativelyconstant slip rate in the past 15 ka. We calculate an average slip rate of 4.7± 1.3 mm/yr since 15 ka based on the three separate displacementsand age estimates. Five separate offsets of 3 m were measured from gullybends and the offset of small fault-scarp alluvial fans. These displacementdata suggest a coseismic slip of 3 m in the last earthquake, or acumulative slip of 3 m in the past few earthquakes. A maximum slip of3 m correspond to a Mw 7 earthquake that ruptures about 49 km offault length. Using an average slip rate of 4.7 ± 1.3 mm/yr togetherwith a 3-m slip-per-event suggests a maximum earthquake recurrence intervalof this fault segment of 500 to 885 years. 相似文献
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由于南华山北麓断裂带的新活动,使得南华山北麓菜园—乱堆子16公里范围内的21条冲沟发生明显断错,显示出左旋位移指向。本文研究了这些断错冲沟的地质地貌表征、断错冲沟的发育过程和断错量,并根据晚更新世以来沉积物的~(14)C年龄和区域冲沟的溯源侵蚀速率,计算出晚更新世以来南华山北麓断裂带的平均滑动速率为4.3毫米/年;同时,量测出1920年海原8.5级地震震中区地震断层的最位移量为6.9米。根据以上资料,估算出南华山北麓断裂带8.5级强震的重复率约为1600年 相似文献
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本文采用地貌分析法确定了云南省通海—石屏地区第四纪中的地表垂直构造形变。应用这个形变资料,根据弹性位错理论求得区内几条活动断层的错距,其中曲江断裂的右旋水平错距为5公里。指出本区在第四纪中主要受北北西—南东东方向的压应力作用。根据地震裂缝、三边测量、定点基线测量和震源机制资料,求得本区现代构造应力场。作者发现它与第四纪构造应力场是相似的。由曲江断裂的平均5—7毫米/年的水平运动速度去估计,通海7.7级地震平均复发周期为300—400年。作者还指出通海地震前400年内,地震活动形成空区。并利用围空地震资料,求得空区内地震震级M与围空地震的断层总面积S之间存在经验关系, M=1gs-3.8 相似文献
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We present results of a geomorphological and morphotectonic analysis of the northeastern part of the Rif. We show that the present day kinematics of the Rif is characterized by active deformation along the Trougout and Nekor faults in the North-East. Digital Elevation Models of offset drainage features (streams, fluvial terraces) allow determining a normal-left-lateral motion along the Trougout fault and a left-lateral strike-slip motion along the Nekor fault. Preliminary 3He cosmogenic dates of tectonic markers yield vertical and horizontal slip rates of ∼0.9 mm/yr and ∼0.5 mm/yr, respectively along the Trougout fault. The present-day localized transtension seen in the north-eastern Rif morphology (Ras Tarf) is coeval with uplifted marine terraces near the Al Hoceima Bay. U/Th dating of shells yield an average uplift rate of ∼0.2 mm/yr during the past 500 ka. These data show that active transtension in the northeastern Rif is also associated with uplift. These new morphotectonic constraints are consistent with the GPS measurements showing southwestward overall motion of most of the Rif belt with respect to stable Africa. 相似文献
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Although offset and age data from displaced landforms are essential for identifying earthquake clusters and thus testing whether faults slip at uniform or secularly varying rates, it is not clear how the uncertainties in such measurements should be propagated so as to yield a robust fault-slip history (i.e., record of fault displacement over time). Here we develop a Monte Carlo approach for estimating the distribution of geologically reasonable fault-slip histories that fit the offset and age data from a population of dated and displaced landforms. The model assumes that the landforms share common faulting histories, the offset and age constraints are correct, and the fault has not reversed shear sense. Analysis of the model results yields both a precise average slip rate, in the case where a linear fit is applied to the data, and a best-fit fault-slip history, in the case where the linear constraint is removed. The method can be used to test for secular variation in slip because the uncertainty on this best-fit history is quantified. By applying the method to previously published morphochronologic data from faulted late Quaternary terrace risers along the Kunlun fault in China and the Awatere fault in New Zealand, we have assessed the extent to which our modeled average slip rates match previously reported values and the data support previous interpretations of uniform slip rate. The Kunlun data set yields average slip rates of 8.7 + 3.6/?2.1 mm/yr and 5.1 + 1.6/?1.2 mm/yr (68.27% confidence), for the central and eastern reaches of the fault, respectively, both of which match previously published slip rates. Our analysis further indicates that these fault reaches have both slipped uniformly over the latest Quaternary. In contrast, analysis of data from the Saxton River site along the Awatere fault reveals a mid-Holocene deceleration in slip rate from 6.2 + 1.6/?1.4 mm/yr to 2.8 + 1.0/?0.6 mm/yr. This result contradicts previous interpretations of uniform slip along the Awatere fault. The Monte Carlo method we present here for quantifying fault-slip histories using the offset and age data from a population of faulted landforms provides an important tool for distinguishing temporally uniform from secularly varying fault slip. 相似文献
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本文以野外地质调查资料为依据,利用地质的方法,讨论了昌马断裂东段的断层崖特征、断层位移量和沿昌马断裂带的古地震证据,确定了断层崖年龄和断层活动速率,粗略地估算了大震复发周期。研究结果表明自全新世以来北东东向断裂的活动性质由压性变为左旋张扭性;断层崖是断裂左旋张扭性活动的结果。断层的水平位移具有分级特点,断层崖具有两个明显的坡度中断,其形成年龄分别为12760年和1880年。公元104年前后,沿昌马断裂可能发生过一次7～7(1/2)级地震,大震复发周期为2620年(考虑蠕滑)和1500年(不考虑蠕滑),12760年和1880年以来的断层水平运动速率分别为4.5毫米/年和6.5毫米/年,水平位移与垂直位移之比值为4.7。 相似文献
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Matthieu Ferry Mustapha Meghraoui Najib Abou Karaki Masdouq Al-Taj Hani Amoush Salman Al-Dhaisat Majdi Barjous 《Earth and Planetary Science Letters》2007,260(3-4):394-406
We investigate the late Quaternary active deformation along the Jordan Valley segment of the left-lateral Dead Sea Fault and provide new insights on the behaviour of major continental faults. The 110-km-long fault segment shows systematic offsets of drainage systems surveyed at three sites along its southern section. The isotopic dating of six paleoclimatic events yields a precise chronology for the onset of six generations of gully incisions at 47.5 ka BP, 37.5 ka BP, 13 ka BP, 9 ka BP, 7 ka BP, and 5 ka BP. Additionally, detailed mapping and reconstructions provide cumulative displacements for 20 dated incisions along the fault trace. The individual amounts of cumulative slip consistently fall into six distinct classes. This yields: i) an average constant slip rate of 4.7 to 5.1 mm/yr for the last 47.5 kyr and ii) a variable slip rate ranging from 3.5 mm/yr to 11 mm/yr over 2-kyr- to 24-kyr-long intervals. Taking into account that the last large earthquake occurred in AD 1033, we infer 3.5 to 5 m of present-day slip deficit which corresponds to a Mw 7.4 earthquake along the Jordan Valley fault segment. The timing of cumulative offsets reveals slip rate variations critical to our understanding of the slip deficit and seismic cycle along major continental faults. 相似文献