色尔腾山山前断裂得令山以东段晚第四纪活动特征与古地震事件

色尔腾山山前断裂得令山以东段属全新世活动断裂。距今约 30ka以来 ,断裂上升盘的平均抬升速率为 :大佘太段 0 19mm/a ,乌兰忽洞段 0 2 0mm/a。探槽揭露 ,大佘太段 ,约 32kaBP以来 ,发生过 4次古地震事件 ,事件发生时间依次为 (316 90± 1770 ) ,(2 30 0 0± 132 0 ) ,(15 42 0± 870 ) ,(74 40± 4 40 )aBP ,相应的位移量分别为 2 6 ,1 6 ,2 2 ,1 4m ;乌兰忽洞段 ,约 2 5kaBP以来 ,也发生过4次古地震事件 ,事件发生时间依次为 (2 5 130± 14 30 ) ,(14 5 70± 82 0 ) ,(116 6 0± 6 5 0 ) ,(72 2 0± 4 0 0 )aBP ,相应的位移量分别为 2 6 ,1 8,1 3,1 2m。根据位移量限定法 ,两个活动段落的古地震活动历史是完整的     

色尔腾山山前断裂晚第四纪活动与破裂分段模型

通过对断裂的几何结构、晚第四纪活动构造特征、古地震活动性以及分段边界构造特征等方面的分析和研究，色尔腾山山前断裂的活动段落组成可以初步确定为：乌加河段(东乌盖沟-大后店)、乌句蒙口-东风村段(大后店-得令山)、大余太段(得令山-小余太沟口)和乌兰忽洞段(小余太沟口-台梁)等4段，其间的段落边界分别为大后店山咀、得令山山咀和小余太沟口阶区。这些段落为相互独立的地震活动单元，但不能排除乌加河段和乌句蒙口-东风村段之间、大余太段和乌兰忽洞段之间联合破裂的可能。     

内蒙古色尔腾山山前断裂(乌句蒙口-东风村段)的断层活动与古地震事件

通过对色尔腾山山前断裂乌句蒙口 -东风村段的遥感资料解释、野外地质地貌考察 ,并通过对重点地段的古地震探槽开挖 ,获得了该断裂段晚更新世晚期以来的垂直位移速率是 0 88～ 1 83mm a ,全新世中期以来的垂直位移速率是 0 89mm a。通过 2个大型探槽的开挖、古地震事件分析和相关堆积物的断代研究 ,以及用逐次限定方法分析整个断层段上的古地震事件 ,认定该断裂段上全新世以来发生了 5次古地震事件 :事件 1发生在距今 90 0 0± 130 0年 ,事件2发生在距今 6 5 0 0± 5 0 0年 ,事件 3发生在距今 5 5 70年左右 ,事件 4发生在距今 4 2 0 0± 30 0年 ,事件 5发生在距今 32 5 0± 2 5 0年。晚更新世晚期到距今 1万年之间 ,古地震事件很不完整。全新世以来的 5次古地震事件表现出一定的丛集特征。最早的一丛事件发生在距今 890 0年左右 ,第2丛发生在距今 6 5 0 0～ 5 70 0年之间 ,第 3丛事件发生在距今 32 5 0～ 4 2 0 0年之间。第 1丛与第 2丛古地震事件之间间隔为 2 4 0 0年左右 ,而第 2丛与第 3丛古地震事件之间仅间隔 15 70年左右。距今 32 5 0年以来 ,该断裂段上还没有发生过错断地表的地震事件 ,已经超出了古地震丛之间的重复间隔。因此 ,它是色尔腾山前活动断裂带上具备潜在危险的一个活动断裂段。     

色尔腾山山前断裂东段与西段转折处构造演化特征

色尔腾山山前断裂位于鄂尔多斯块体西北角,控制着临河凹陷（河套盆地西部）的持续沉降。对色尔腾山山前断裂东段与西段转折处构造演化模式的研究,有助于提高对正断层演化规律和区域地震风险的认识。本文在研究区大比例尺活动断裂填图的基础上,通过对重点区域进行无人机微地貌的测量、探槽开挖、钻孔资料与第四纪测年等方法获取数据,并运用构造地质学、地貌学和沉积地层学等理论,综合探讨断层转折处的构造演化模式及地震危险性。通过研究认为,近东西走向的色尔腾山山前断裂西段与北西走向的东段间以三角状的转换斜坡相连。现今的转折点为应力的积累区,具有较高的地震风险。水平拉伸力的持续作用使断层不断向盆地一侧迁移,同时使断裂转折部位更加平滑。     

内蒙大青山山前活动断裂带的地震破裂分段特征

沿内蒙大青山山前活动断裂进行野外调查及探槽开挖的研究结果表明 ,该断裂西部地段及东部地段的最新活动时期在全新世中期以后及全新世晚期以前 ;中部地段在全新世晚期强烈活动 ,公元 84 9年包头地震的地表破裂沿该段展布。大青山山前台地与断层陡坎分布、洪积扇类型及河流阶地断错等地貌特征、全新世晚期断裂活动范围、沿断裂带探槽开挖获得的古地震事件对比 ,以及现今中小地震震中分布表明 ,全新世晚期大青山山前断裂的活动以土左旗为界 ,该界以西全新世晚期断裂强烈活动 ,该界以东全新世晚期断裂活动不明显。全新世时期大青山山前断裂的活动显示了由东向西的迁移     

六盘山东麓断裂的古地震研究

野外详细调查和探开挖揭示,在六盘山东麓断裂的孙家庄－海子峡地段自距今４．６万年以来存在有６次古地震位借事件的地质形迷,它们分别发生在距今３５２５０,２０２５０,１４７５０,１２１５０,８５５０和４０００年前,各次事件的重复间隔依次是１５０００,５５００,２６００,３６００和４５５０年。按Ｍ－Ｄ经验关系,事件１,２约相当于８级地震的位错,其余各次事件约相当６．５－７．５级地震的位错。     

海原活动断裂带的古地震与强震复发规律

海原断裂是中国西部的一条重要活动走滑断裂带, 1920年沿该带发生的8.5级强震形成了230 km长的地表破裂带和10 m的左旋走滑位移. 为了揭示这条重要发震断裂的强震活动规律, 沿断裂带的3个段落开挖了17个探槽, 揭示了大量的古地震事件, 并结合前人的研究结果, 利用古地震分析的逐次限定方法研究了海原断裂带的强震复发规律. 研究发现, 海原断裂带的3个段落具有分段差异的古地震活动历史; 古地震破裂有3种尺度, 即单段破裂、双段破裂和全段破裂. 另外, 整个海原断裂带的古地震丛集现象也十分明显, 第1丛集期在距今4600~6300 a期间, 第2丛集期发生在距今1000~2800 a期间. 海原断裂带的古地震活动习性对于认识大陆走滑断裂的破裂特征和强震复发规律具有十分重要的意义.     

昌马断裂带古地震活动特征的新认识

昌马断裂位于祁连山西段,是祁连山系列次级断裂与阿尔金断裂东段的重要构造转换断层之一,于1932年发生7.6级地震。位于昌马断裂中东段的臭水柳沟古地震探槽揭示了2次地震事件:一次为1932年昌马地震事件,另一次为(902±44)a B.P.以来发生的事件,这弥补了昌马断裂全新世晚期古地震事件缺失的现状。结合前人的研究结果可确定昌马断裂全新世至少发生7次古地震事件,推测地震复发间隔为1ka左右,部分事件未能揭示。通过探槽揭示的低角度断层、地层变形和部分断裂的地貌特征可知,受阿尔金断裂NEE向挤出的影响,昌马断裂部分段落表现出低角度的逆冲推覆活动,形成其特有的低角度走滑现象,以吸收阿尔金断裂东段的左旋位移。这也说明昌马断裂在承担阿尔金断裂与祁连山西段系列断层的构造转换中起着重要作用。     

则木河活动断裂带大震重复间隔

通过对则木河活动断裂带上古地震的研究,讨论该断裂带的大震重复间隔问题,经分析后认为其大震间隔时间为1000年～3000年。     

大青山山前断裂呼和浩特段晚第四纪古地震活动历史

通过沿大青山山前断裂呼和浩特段的奎素、乌兰不浪和青山牧场 3个地点地貌面和探槽组的精细研究 ,揭露出该断裂段距今约 1 9万年以来共发生 7次古地震事件。它们分别发生在距今约 1 875± 0 0 75、1 6 97± 0 0 96、1 4 6 5± 0 0 6 7、1 182± 0 0 6 9、0 94 5± 0 0 2 6、0 6 83±0 0 2 6和 0 4 5 0± 0 0 2 3万年 ,平均重复间隔 2 375± 4 32年。由断层位移量限定法和多探槽校验法判定 ,这一时期该断裂段的古地震活动历史是完整的     

安宁河断裂带小相岭段古地震的新证据及最晚事件的年代

沿安宁河断裂带小相岭段发现了古地震的地表破裂遗迹。在两个场地开挖了横跨主断裂的探槽 ,以研究这里的晚全新世古地震。结果表明 ,在最近的大约 2 30 0a中 ,该断裂段至少发生过 4次伴有地表破裂的古地震事件 ,平均复发间隔为 6 0 0～ 70 0a。这里的最晚事件很可能发生在公元 15世纪 ,并且有可能发生在公元 14 80年。最晚事件沿地表断层产生了 3m的平均左旋位错 ,这相当于一次矩震级为 7 5± 0 3的走滑型大地震的同震平均位错量     

中卫-同心断裂带全新世古地震研究

通过对中卫 -同心断裂带中段和西段 7个新探槽的古地震研究 ,并结合前人对中段古地震的研究结果 ,分析确定出 140 0 0a以来中卫 -同心断裂带共发生 6次古地震事件。其中仅有 1次是破裂全带的 ,发生在晚更新世末 ,其它都为全新世以来的次级破裂事件 ,3次破裂中段 ,两次破裂西段。公元 170 9年 7 级历史地震只破裂中段 ,因此推断只破裂中段或西段的古地震震级约为 7 级左右 ;破裂全带的古地震震级应为 8级左右。从时间上看 ,这 6次事件的分布是不均匀的 ,但没有明显的丛集现象     

罗山东麓断裂全新世古地震研究

罗山东麓断裂全新世活动强烈,古地震现象丰富。探槽揭露出晚更新世末或全新世初以来,已发生过5次7级左右的古地震事件,除最早的一次时间不明外,其它4次分别发生在距今约8400年、5400—5020年、3900年和2260年。全新世早期古地震重复间隔在3000年左右,晚期为1500年左右。     

Paleoseismic activity on Wujiahe segment of Serteng piedmont fault,inner Mongolia

Geomorphic study on Wjiahe segment of Serteng piedmont fault,Inner Mongolia is made.Throuth analysis of the available data in combination with the results of predecessors‘studies it can be obtained that average vertical displacement rate is 0.48-0.75mm/a along the Wujiahe segment since the late Pleistocene(14.450-22.340ka BP)and 0.56-0.88mm/s since the early-middle Holocene(5.570-8.830ka BP).Analyzing paleoseismic phenomena revealed in the excavated 5trenches in combination with the results of predecessors‘studies of paleoearthquakes on the fault,we determine five paleoseismic events on the Wujiahe segment of Serteng piedmont fault since 27.0ka BP and the recurrence interval to be about 4.300-4.400ka,A cluster of paleoearthquakes occurred probably during 8.000-9.000ka BP and two paleoeismic events in 10.000-20.000ka BP may be missed.A comparison between height of fault scarps and sum of displacement caused by paleoseismic events revealed in trenches,and recurrence interval of paleoseismic events obtained from average displacement rate along the fault and the disloca-tion by one event suggest that three paleoseismic events are absent in Alagaitu trench.Two paleoseismic events may be absent on the whole active fault segment.     

阿尔金断裂东段断层泥特征及断层滑动方式

本文用扫描电镜、X衍射等方法对阿尔金断裂东段断层泥的特征、断层活动强度及断层滑动方式进行了研究,获得了如下结论: (1)阿尔金断裂东段的活动强度自晚更新世以后,由西往东逐渐减弱。(2)该断裂东段在第四纪以来至少发生过2—3次古地震事件。(3)全新世以来,该断裂的肃北至阿克塞一段以粘滑为主,而东边的巴个峡至昌马大坝之间断裂的滑动方式则为蠕滑。     

PRELIMINARY STUDY OF PALEOEARTHQUAKES ON THE MIDDLE-EASTERN SEGMENT OF JINTA NANSHAN FAULT

Hexi Corridor is located at the northeastern margin of the Tibetan plateau. Series of late Quaternary active faults are developed in this area. Numerous strong earthquakes occurred in history and nowadays. Jinta Nanshan fault is one of the boundary faults between the Qinghai-Tibet block and the Alxa block. The fault starts from the northwest of Wutongdun in the west, passes through Changshan, Yuanyangchi reservoir, Dakouzi, and ends in the east of Hongdun. Because the Jinta Nanshan fault is a new active fault in this region, it is important to ascertain its paleoearthquakes since late Pleistocene for the earthquake risk study. Previous studies were carried out on the western part, such as field geomorphic investigation and trench excavation, which shows strong activity in Holocene on the western segment of Jinta Nanshan fault. On the basis of the above research, in this paper, we carried out satellite image interpretation, detailed investigation of faulted landforms and differential GPS survey for the whole fault. Focusing on the middle-eastern part, we studied paleoearthquakes through trench exploration on the Holocene alluvial fan and optical luminescence dating. The main results are as follows:Early Pleistocene to late Pleistocene alluvial strata are widely developed along the fault and Holocene sediment is only about tens of centimeters thick. The Jinta Nanshan fault shows long-lasting activity since late Quaternary and reveals tens of centimeters of the lowest scarp which illustrates new strong activity on the middle-east segment of this fault. Since late Pleistocene, 4 paleoearthquakes happened respectively before(15.16±1.29) ka, before(9.9±0.5) ka, about 6ka and after(3.5±0.4) ka, revealed by 4 trenches, of which 2 are laid on relatively thicker Holocene alluvial fan. Two events occurred since middle Holocene, and both ruptured the whole fault.     

海原断裂高湾子地点三维探槽的开挖与古地震研究

对海原断裂高湾子地点进行大比例尺地质地貌填图和三维探槽开挖，揭示出７次古地震事件，除１９２０年地震外，它们的年龄分别为距今（１０００４±３１９６），（６６８９±１６９），（６１２０±５０５），（４２０８±５７７），（２７６３±３７２）和（１００５±４６５）ａ；重复间隔分别为（３３１５±３２００），（５６１±５３２），（１９２０±７６６），（１４２５±６８６），（１５７８±５９５）和（９８０±４６５）ａ。事件Ⅲ，Ⅳ，Ⅴ，Ⅵ，Ⅶ的水平位移量分别为（５．６±２．３），（１．５±１．１），（１．５±１．１），（２±１）和（７±０．５）ｍ。显示出重复间隔时间的分段性和特征行为的分级性。两次类似１９２０年强度的地震间隔期间，有３次位移量为１～２ｍ的地震发生     

LATE QUATERNARY FAULTED LANDFORMS AND FAULT ACTIVITY OF THE HUASHAN PIEDMONT FAULT

Based on the 1︰50000 active fault geological mapping, combining with high-precision remote imaging, field geological investigation and dating technique, the paper investigates the stratum, topography and faulted landforms of the Huashan Piedmont Fault. Research shows that the Huashan Piedmont Fault can be divided into Lantian to Huaxian section (the west section), Huaxian to Huayin section (the middle section) and Huayin to Lingbao section (the east section) according to the respective different fault activity. The fault in Lantian to Huaxian section is mainly contacted by loess and bedrock. Bedrock fault plane has already become unsmooth and mirror surfaces or striations can not be seen due to the erosion of running water and wind. 10~20m high fault scarps can be seen ahead of mountain in the north section near Mayu gully and Qiaoyu gully, and we can see Malan loess faulted profiles in some gully walls. In this section terraces are mainly composed of T₁ and T₂ which formed in the early stage of Holocene and late Pleistocene respectively. Field investigation shows that T₁ is continuous and T₂ is dislocated across the fault. These indicate that in this section the fault has been active in the late Pleistocene and its activity becomes weaker or no longer active after that. In the section between Huaxian and Huayin, neotectonics is very obvious, fault triangular facets are clearly visible and fault scarps are in linear distribution. Terrace T₁, T₂ and T₃ develop well on both sides of most gullies. Dating data shows that T₁ forms in 2~3ka BP, T₂ forms in 6~7ka BP, and T₃ forms in 60~70ka BP. All terraces are faulted in this section, combing with average ages and scarp heights of terraces, we calculate the average vertical slip rates during the period of T₃ to T₂, T₂ to T₁ and since the formation of T₁, which are 0.4mm/a, 1.1mm/a and 1.6mm/a, and among them, 1.1mm/a can roughly represent as the average vertical slip rate since the middle stage of Holocene. Fault has been active several times since the late period of late Pleistocene according to fault profiles, in addition, Tanyu west trench also reveals the dislocation of the culture layer of(0.31~0.27)a BP. 1~2m high scarps of floodplains which formed in(400~600)a BP can be seen at Shidiyu gully and Gouyu gully. In contrast with historical earthquake data, we consider that the faulted culture layer exposed by Tanyu west trench and the scarps of floodplains are the remains of Huanxian M_S8½ earthquake. The fault in Huayin to Lingbao section is also mainly contacted by loess and mountain bedrock. Malan loess faulted profiles can be seen at many river outlets of mountains. Terrace geomorphic feature is similar with that in the west section, T₁ is covered by thin incompact Holocene sand loam, and T₂ is covered by Malan loess. OSL dating shows that T₂ formed in the early to middle stage of late Pleistocene. Field investigation shows that T₁ is continuous and T₂ is dislocated across the fault. These also indicate that in this section fault was active in the late Pleistocene and its activity becomes weaker or no longer active since Holocene. According to this study combined with former researches, we incline to the view that the seismogenic structure of Huanxian M_S8½ earthquake is the Huashan Piedmont Fault and the Northern Margin Fault of Weinan Loess, as for whether there are other faults or not awaits further study.     

大凉山断裂带北段石棉断裂的古地震

大凉山断裂带是大型走滑断裂鲜水河-小江断裂系的重要组成部分,其活动性是认识和探讨青藏高原东南缘现今地震活动和构造变形机制的重要基础资料.相较于中段和南段,关于大凉山断裂带北段活动性的相关研究成果,尤其是古地震资料非常缺乏.文中基于野外地质地貌调查,在石棉断裂联合村处开挖了一组(2个)探槽,揭露出断裂全新世活动的直接证据...