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1.
山西交城断裂带多个大探槽全新世古地震活动对比研究 总被引：6，自引：2，他引：4
介绍了沿交城断裂带5个地点开挖探槽揭示的古地震情况.这5个大探槽分别沿交城断裂带北、中、南段分布,其中北段和中段各有2个地点,南段1个地点,探槽之间相距 11～35km.位于该断裂带北段和中段的4个探槽出露了断错全新世地层的断面,在这4个探槽中,位于断裂带北段的西张探槽和位于断裂带中段的新民探槽揭示的全新世3次古地震事件可进行对比,具有活动的同步性.由此显示交城断裂带的中段和北段在距今3 060～3 740a、接近5 910a及8 530～8 560a期间,曾发生3次有地表破裂的古地震事件.位于断裂带北段的冶峪探槽,由于探槽位于台地内冲沟右旋扭曲处,断错的最新地层的年代距今10 730a,其它断面断错晚更新世地层.位于断裂带中段的上固驿探槽地处洪积扇,断层带宽70m,断层走向N58°～74°E,断错的最新地层距今11 570a,揭示了NEE向田庄断层晚更新世时期的活动.位于断裂带南段窑头探槽所在的原始地形受到人工改造影响,探槽剖面揭示全新统覆盖在显示距今 3.0～3.5万年期间受到断裂活动影响的地层之上.交城断裂带5个地点的探槽开挖结果显示,该断裂带全新世时期的活动自南向北迁移. 相似文献
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西张探槽①位于山西太原市西北10km,沿交城断裂带北段NNW方向高4.6m的低陡坎前缘开挖。探槽长108m,宽8m,深10m,揭露18层地层。探槽上部地层为亚砂土,探槽内断层下降盘的上部地层为一套砾石层,下部地层为一套褐色垆土与亚砂土互层,断层的上升盘地层以亚砂土为主夹砾石层。探槽揭露出3条断面,断面的上断点距地表1.5m,断错的最新地层距今(3.74±0.06)ka。探槽揭示出断面、地层断错、崩积楔、地层倾斜等现象。由探槽揭露出的地层与断层的关系可知早全新世以来交城断裂带曾发生3次断层活动事件,其时间分别为距今(3.74±0.06)～(3.06±0.26)ka、(8.35±0.09)～(3.74±0.06)ka与(10.66±0.85)～(8.35±0.09)ka,具有2.6～3.6ka的强震重复间隔;3次同事件最小垂直位移分别为3.0m、2.5m及3.2m。西张探槽的意义在于揭示了历史上未有强震记载的晋中盆地几千年前有过多次强震活动。西张探槽获得的交城断裂带全新世古地震活动的依据,对评价太原市未来的强震危险性具有重要意义 相似文献
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断错地貌调查和探槽开挖是获取活动断裂多期活动重要的线索．介绍了龙门山中央断裂带北川县城及平武县平通镇的断层沟槽调查及龙门山前山断裂带绵竹县汉旺镇台地前缘探槽开挖获得的认识．调查结果表明,北川断层沟槽包括汶川地震在内至少存在3次断层活动事件;平通断层沟槽包括汶川地震在内至少存在两次以上断层活动事件;汉旺探槽揭示了2-3次古地震事件．在上述3个地点中,北川断层沟槽和汉旺探槽在汶川地震前的一次强震时间接近,分别为大于5．8ka和小于6．63ka,接近为6ka．由此也获取了在汶川地震前龙门山活动断裂带的一次强震活动中,中央断裂带和前山断裂带同时活动的证据． 相似文献
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山西断陷系交城断裂全新世古地震活动初步研究 总被引：9，自引：0，他引：9
断错地貌调查及探槽开挖表明,晋中盆地西界分布的黄土台地的前、后缘均存在断层,断层的最新活动位于地表陡坎的前缘,地表见到的断层最新活动断面的上升盘是早全新世地层。同时,新民探槽开挖表明,该断裂在早全新世以后曾发生三次古地震事件,最新一次活动接近距今2748a,另两期古地震事件的时间分别距今4037～5910a及8360～5910a。如果取后两次古地震事件时间跨度的中值,这三次古地震事件的间隔分别是2225a和2162a,平均2193a。 相似文献
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青藏高原东北缘热水-日月山断裂带热水段古地震初步研究 总被引：1，自引：0，他引：1
通过遥感影像解译和详细的野外填图,获得了热水-日月山断裂带热水断裂段的断错地貌,其水系右旋断错量为140～940m.沿断裂带的探槽开挖,揭示距今9645±220 a B.P,热水段曾发生一次古地震事件;结合前人的研究结果,认为热水-日月山断裂带热水断裂段上古地震复发间隔约3365 a,全新世以来的倾滑速率为0.03 mm/a.热水-日月山断裂带上已揭露出3次古地震事件,分别为9865±40 a B.P～9425±35 aB.P,6280±120 a B.P和2220±360 a B.P,复发间隔为3500 a左右,由于该断裂段最近一次古地震事件距今已接近2220年,与其复发间隔3365 a年相比尚有一段时间,但考虑到古地震事件的不确定性和年代样品的误差,初步推断热水-日月山断裂带热水段的地震危险性不大,但不排除有中强地震的可能性. 相似文献
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佛洞庙-红崖子断裂位于祁连山北缘断裂带中段,是1条活动逆断裂。在佛洞庙-红崖子断裂东、中、西各段落开挖整理了5个探槽。通过探槽揭示的各地层单元的沉积特征、各单元之间的层序关系以及断层对不同地层的切割关系,共辨认出了4次古地震事件。根据探槽中各地层单元的14C样品和光释光样品测年结果,对4次古地震事件给出了年龄制约:最早事件E4发生在距今约10.6ka,事件E3发生在距今约7.1ka,事件E2发生在距今约3.4ka,事件E1为1609年红崖堡地震。这4次地震事件的间隔分别约3.5ka、3.7ka和3.0ka,平均复发间隔约3.4ka,具有准周期重复特征。 相似文献
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柯坪塔格断裂位于西南天山柯坪塔格推覆构造的最前缘,以皮羌断裂为界分成东西两段。在柯坪塔格断裂西段开挖了6个规模较大的探槽,6个探槽都揭露出断层,但其中3个探槽的古地震事件不清晰,另外3个探槽有古地震遗迹。通过分析研究,共确定了全新世以来的4次古地震事件:第1次古地震事件发生于距今约12ka,第2次事件发生于距今约8·6ka,第3次事件大致发生于距今约5ka,第4次事件发生于距今(1·73±0.15)ka以来,很可能是1961年西克尔6·8级地震。这4次古地震事件具有约3~5ka的准周期重复特征。天山南麓有5~6排推覆体,每排推覆体的前缘都发育活动逆断裂,它们向下收敛于寒武系底部的滑脱面,因此,天山南麓的地震破裂非常复杂,这4次古地震事件的震级、发震构造等问题都有待于今后的深入研究 相似文献
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野外调查表明 ,口泉断裂断错了断面附近的 3级地貌面 ,包括大同盆地西侧全新世形成的洪积扇后缘及位于洪积扇冲沟内的Ⅰ ,Ⅱ级阶地。其中冲沟内Ⅱ级阶地为剥蚀阶地 ,Ⅰ级阶地为堆积阶地 ,Ⅰ级阶地面的地层时代距今 2 52ka。在该断裂的悟道及上黄庄 2个地点开挖的大探槽表明 ,在距今 1 2 3万年以来该断裂曾发生 4次古地震事件 ,其中 3次分别发生在接近距今 2 52 ,5 6 8,13 73ka。另一次古地震事件发生在距今 6 76～ 10 82ka。这些数据有可能反映了口泉断裂具备准周期的强震活动。这 4次古地震事件的平均间隔约为 3 74ka ,最新一次古地震与上一次事件的时间间隔约为 3 16ka。 2个大探槽各次事件的平均最小同震垂直位移为 1 8m。这些资料对重新评价口泉断裂未来的地震潜势具有重要意义 相似文献
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钻孔与探槽揭示1976年河北唐山M_s7.8地震发震构造晚第四纪强震活动 总被引：1，自引：0，他引：1
钻孔联合剖面探测匹配探槽开挖是获取平原区隐伏活动断裂多次活动地质依据的有效途径.本项研究跨唐山市1976年唐山地震地表破裂带实施了3条钻孔联合剖面探测及1个大探槽开挖,取得以下3点主要认识：（1）1976年唐山Ms7.8地震的地表破裂带长度大于47km,自唐山市市区南部向南过丰南县稻地镇孙家楼西侧至丰南县西河.（2）该地震地表破裂带的几何展布分为南支和北支.北支以右旋走滑为主,地表垂直位移为西升东降;南支地表垂直位移表现为东升西降,兼具右旋走滑.这种断层活动方式无法用单一的正断层或逆断层的活动给予解释,而与断裂带右旋走滑活动产生的垂直位移场吻合.研究获得的钻孔和探槽资料证实晚第四纪时期唐山断裂存在这种持续的活动方式.（3）探槽揭示的断面和钻孔揭示的地层断错现象表明,晚第四纪时期唐山断裂带曾发生多次断层活动事件.在1976年唐山地震之前3次断层活动的时间分别为距今7.61~8.13,〉14.57和24.21~26.57ka,连同1976年唐山地震在内这4次强震的时间间隔约为6.7~10.8ka.在3条钻孔测线中,牛马库钻孔测线距今75.18ka以来9次事件断层活动的平均间隔为8.4ka.同时文中根据地层测年结果讨论了唐山市南北侧晚第四纪沉积环境的差异. 相似文献
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The Fodongmiao-Hongyazi Fault is a Holocene active thrust fault, belonging to the middle segment of northern Qilianshan overthrust fault zone, located in the northeastern edge of the Tibet plateau. The Hongyapu M7(1/4) earthquake in 1609 AD occurred on it. A few paleo-seismology studies were carried out on this fault zone. It was considered that four paleoearthquakes occurred on the Fodongmiao-Hongyazi Fault between(6.3±0.6) ka BP and(7.4±0.4) ka BP, in(4.3±0.3) ka BP, in(2.1±0.1) ka BP and in 1609 AD. The occurrences of the earthquakes suggested the quasi-periodic characteristic with a quasi-periodic recurrence interval between 1 600~2 500a(Institute of Geology, State Seismological Bureau, Lanzhou Institute of Seismology, State Seismological Bureau. 1993; Liu et al., 2014). There was no direct evidence for the Hongyapu M7(1/4) earthquake in 1609 AD from trench research in the previous studies. Great uncertainty exists because of the small number of the chronology data, as a few TL and OSL measurement data and several14 C data, and it was insufficient to deduce the exact recurrence interval for the paleoearthquakes.
Five trenches were excavated and cleared up respectively in the eastern segment, middle segment and western segment along the Fodongmiao-Hongyazi Fault. After detail study on the trench profiles, the sedimentary characteristics, sequence relationship of the stratigraphical units, and fault-cuts in different stratigraphical units were revealed in these five trenches. Four paleoearthquakes in Holocene were distinguished from the five trenches, and geology evidences of the Hongyapu M7(1/4) earthquake in 1609 AD were also found.
More accurate constraint of the occurring time of the paleo-earthquakes since Holocene on the Fodongmiao-Hongyazi Fault is provided by the progressive constraining method(Mao and Zhang, 1995), according to amounts of 14 C measurement data and OLS measurement data of the chronology samples from different stratigraphical units in the trenches. The first paleoevent, E4 occurred 10.6ka BP. The next event, E3 occurred about 7.1ka BP. The E2 occurred about 3.4ka BP. The last event, E1 is the Hongyapu M7(1/4) earthquake in 1609 AD.
Abounds of proofs for the occurrences of the events of E1, E2 and E3 were found in the trench Tc1, trench Tc2, trench Tc4 and trench Tc3, located in the eastern, middle and western segments of the Fodongmiao-Hongyazi Fault accordingly. It's considered that the events E1, E2 and E3 may cause whole segment rupturing according to the proofs for these three events found together in individual trenches. The event E4 was only found in the trench Tc5 profile in the west of the Xiaoquan village in the eastern segment of the Fodongmiao-Hongyazi Fault. The earthquake rupture characteristics of this event can't be revealed before more detailed subsequent research.
The time intervals among the four paleoearthquakes are ca 3.5ka, ca 3.7ka, and ca 3.0ka. The four events are characterized by ca 3.4ka quasi-periodic recurrence interval. 相似文献
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RUPTURE CHARACTERISTICS OF LATE QUATERNARY STRONG EARTHQUAKES ON THE WESTERN BRANCH OF THE XIAOJIANG FAULT ZONE 
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下载免费PDF全文 The Xiaojiang fault zone is located in the southeastern margin of the Tibetan plateau, the boundary faults of Sichuan-Yunnan block and South China block. The largest historical earthquake in Yunnan Province, with magnitude 8 occurred on the western branch of the Xiaojiang Fault in Songming County, 1833. Research on the Late Quaternary surface deformation and strong earthquake rupture behavior on the Xiaojiang Fault is crucial to understand the future seismic risk of the fault zone and the Sichuan-Yunnan region, even crucial for the study of tectonic evolution of the southeastern margin of Tibetan plateau. We have some new understanding through several large trenches excavated on the western branch of the Xiaojiang fault zone. We excavated a large trench at Caohaizi and identified six paleoseismic events, named U through Z from the oldest to the youngest. Ages of these six events are constrained at 40000-36300BC, 35400-24800BC, 9500BC-500AD, 390-720AD, 1120-1620AD and 1750AD-present. The Ganhaizi trench revealed three paleoearthquakes, named GHZ-E1 to GHZ-E3 from the oldest to the youngest. Ages of the three events are constrained at 3300BC-400AD, 770-1120AD, 1460AD-present. The Dafendi trench revealed three paleoearthquakes, named E1 to E3 from the oldest to the youngest, and their ages are constrained at 22300-19600BC, 18820-18400BC, and 18250-present. Caohaizi and Ganhaizi trenches are excavated on the western branch of the Xiaojiang Fault, the distance between them is 400m. We constrained four late Holocene paleoearthquakes with progressive constraining method, which are respectively at 500-720AD, 770-1120AD, AD 1460-1620 and 1833AD, with an average recurrence interval of 370~440a. Large earthquake recurrence in the late Holocene is less than the recurrence interval of~900a as proposed in the previous studies. Thus, the seismic hazard on the Xiaojiang Fault should be reevaluated. We excavated a large trench at Dafendi, about 30km away south of Caohaizi trench. Combining with previous paleoseismological research, it is found that the western branch of Xiaojiang Fault was likely to be dominated by segmented rupturing in the period from late of Late Pleistocene to early and middle Holocene, while it was characterized by large earthquakes clustering and whole segment rupturing since late Holocene. 相似文献
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ACTIVITY FEATURES OF FAULTS AT THE EAST OF ZHANGSHAN ON THE MIDDLE SEGMENT OF TANLU FAULT ZONE 下载免费PDF全文
下载免费PDF全文 Given the scarcity of research on the activity of Xinyi-Sihong segment of the Tanlu Fault zone, this paper focuses on the Zhangshan segment where there are quite evident geomorphic features to complement the shortage of the research on the northern part of Xinyi-Sihong segment. This study enriches evidences for the late Quaternary activity and paleoseismological events on the Xinyi-Sihong segment. The Zhangshan segment is located at Xiaodian Town to Jintou Village of Suqian City, stretching towards NE for 7 kilometers with a dip angle of 60~80. Research of tectonic geomorphology shows that gullies in northern part of Zhangshan segment were evidently displaced, while in the southern, two NE-trending right-stepped fault scarps are developed, with an average height of 3 meters, which generally suggests that the fault was dominated by thrust and dextral motion. Two trenches were excavated in the southern part of Zhangshan segment, numbered Mayao trench 1 and Mayao trench 2. Both trenches reveal that:(1)within this segment, Tanlu Fault shows periodic fault activity, that is, normal faulting during Pliocene epoch while thrust faulting in Quaternary period; (2)an event occurred between 15.12ka BP to 11.82 BP; (3)the latest event possibly took place around 3 500 a BP. Based on integrated results of previous studies, we identify the dates of paleoseismic events on the Xinyi-Sihong segment as follows:more than 960 thousands years ago, early to middle period of late Pleistocene, (15.12~11.82)ka BP, (11.76±0.05)ka~(10.53±0.05)ka BP, (10.15±0.05)ka~(8.16±0.05)ka BP and 4 960~3 510a BP. 相似文献
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The Bolokenu-Aqikekuduk fault zone(B-A Fault)is a 1 000km long right-lateral strike-slip active fault in the Tianshan Mountains. Its late Quaternary activity characteristics are helpful to understand the role of active strike-slip faults in regional compressional strain distribution and orogenic processes in the continental compression environment, as well as seismic hazard assessment. In this paper, research on the paleoearthquakes is carried out by remote sensing image interpretation, field investigation, trench excavation and Quaternary dating in the Jinghe section of B-A Fault. In this paper, two trenches were excavated on in the pluvial fans of Fan2b in the bulge and Fan3a in the fault scarp. The markers such as different strata, cracks and colluvial wedges in the trenches are identified and the age of sedimentation is determined by means of OSL dating for different strata. Four most recent paleoearthquakes on the B-A Fault are revealed in trench TC1 and three most recent paleoearthquakes are revealed in trench TC2. Only the latest event was constrained by the OSL age among the three events revealed in the trench TC2. Therefore, when establishing the recurrence of the paleoearthquakes, we mainly rely on the paleoearthquake events in trench TC1, which are labeled E1-E4 from oldest to youngest, and their dates are constrained to the following time ranges: E1(19.4±2.5)~(19.0±2.5)ka BP, E2(18.6±1.4)~(17.3±1.4)ka BP, E3(12.2±1.2)~(6.6±0.8)ka BP, and E4 6.9~6.2ka BP, respectively. The earthquake recurrence intervals are(1.2±0.5)ka, (8.7±3.0)ka and(2.8±3)ka, respectively. According to the sedimentation rate of the stratum, it can be judged that there is a sedimentary discontinuity between the paleoearthquakes E2 and E3, and the paleoearthquake events between E2 and E3 may not be recorded by the stratum. Ignoring the sedimentary discontinuous strata and the earthquakes occurring during the sedimentary discontinuity, the earthquake recurrence interval of the Jinghe section of B-A Fault is ~1~3ka. This is consistent with the earthquake recurrence interval(~2ka)calculated from the slip rate and the minimum displacement. The elapsed time of the latest paleoearthquake recorded in the trench is ~6.9~6.2ka BP. The magnitude of the latest event defined by the single event displacement on the fault is ~MW7.4, and a longer earthquake elapsed time indicates the higher seismic risk of the B-A Fault. 相似文献
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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. 相似文献
17.
龙首山北缘断裂带是潮水盆地与龙首山地的地貌分界线,展布于龙首山隆起的北麓。前期曾在龙首山北缘断裂带东段的白家嘴、中段包代河、西段斜坡山开挖了三个探槽,均揭露出多期古地震。本文通过三个探槽古地震事件的对比分析认为,龙首山北缘断裂带第1次古地震(11 ka)到最后1次古地震(1.6 ka)间隔9.4 ka,约1万年时间里有6次古地震发生。如果取算术平均(9.4 ka/6=1.57 ka),则每隔1 500年左右,龙首山北缘断裂带就有一次强地震事件,即古地震平均重复间隔约1.57 ka。这和其它各大断裂带得出的古地震优势重现周期(1~2 ka)并不矛盾。①5 ka年以前龙首山北缘断裂带仅有2次古地震事件,重复间隔5.3 ka,明显偏长,可能有古地震的遗漏问题;②5 ka年以后该断裂地震活动明显丛集,最短间隔0.7 ka,最长间隔1.5 ka,平均重复间隔约0.8 ka。无论是最短、最长或平均重复间隔,均与山丹-张掖地区历史地震的最长重复间隔0.79 ka接近。 相似文献
18.
The relationship between the latest activity of active fault and seismic events is of the utmost importance. The Tan-lu fault zone in eastern China is a major fault zone, of which the active characteristics of the segments in Jiangsu, Shandong and Anhui has been the focus of research. This study takes the Dahongshan segment of the Tanlu Fault in Sihong County as the main research area. We carried out a detailed geological survey and excavated two trenches across the steep slope on the southwest side of the Dahongshan. Each trench shows fault clearly. Combining the comparative analysis of previous work, we identified and cataloged the late Quaternary deformation events and prehistoric earthquake relics, and analyzed the activity stages and behavior of this segment.
Fault gonge observed in the trench profiles shows that multiple earthquake events occurred in the fault. The faulting dislocated the Neogene sandstone, black gravel layer and gray clay layer. Brown clay layer is not broken. According to the relations of dislocated stratums, corresponding 14C and OSL samples were collected and dated. The result indicates that the Dahongshan segment of the Tanlu Fault has experienced strong earthquakes since the late Quaternary. Thrust fault, normal fault and strike-slip fault are found in the trenches. The microscopic analysis of slices from fault shows that there are many stick-creep events taking place in the area during the late Quaternary. Comprehensive analysis shows that there have been many paleoearthquakes in this region since the late Quaternary, the recent active time is the late Pleistocene, and the most recent earthquake event occurred in(12~2.5ka BP).
The neotectonic activity is relatively weak in the Anhui segment(south of the Huaihe River)of Tanlu fault zone. There are difficulties in the study of late Quaternary activity. For example, uneven distribution of the Quaternary, complex geological structure, larger man-made transformation of surface and so on. The progressive research may be able to promote the study on the activity of the Anhui segment of Tanlu fault zone. 相似文献
19.
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。通过古地震分析和炭样加速器质谱仪(AMS)测年,共获得了4次古地震事件:事件E1:20925—16850BC;事件E2:15265—1785BC;事件E3:360—1475AD;事件E4:1655—1815AD。其中包括全新世以来的3次事件,最新2次事件的复发间隔骤然缩短,反映断裂活动可能正在加剧。 相似文献
20.
THE SLIP RATE AND PALEOEARTHQUAKES OF THE YUMEN FAULT IN THE NORTHERN QILIAN MOUNTAINS SINCE THE LATE PLEISTOCENE 下载免费PDF全文
下载免费PDF全文 LI An WANG Xiao-xian ZHANG Shi-min CHEN Zhi-dan LIU Rui ZHAO Jun-xiang L&# Yan-wu 《地震地质》2016,38(4):897-910
The Yumen Fault lies on the west segment of the north Qilian Fault belt and adjacent to the Altyn-Tagh Fault,in the north margin of the Tibet Plateau.The tectonic location of the Yumen fault is special,and the fault is the evidence of recent activity of the northward growth of Tibetan plateau.In recent twenty years,many researches show the activity of the Yumen Fault became stronger from the early Pleistocene to the Holocene.Because the Yumen Fault is a new active fault and fold belt in the Qilian orogenic belt in the north margin of the Tibet Plateau,it is important to ascertain its slip rate and the recurrence interval of paleoearthquakes since the Late Pleistocene.Using the satellite image interpretation of the Beida river terrace,the GPS measurement of alluvial fans in front of the Yumen Fault and the trench excavation on the fault scarps,two conclusions are obtained in this paper.(1) The vertical slip rate of the Yumen Fault is about 0.41~0.48mm/a in the Holocene and about 0.24~0.30mm/a in the last stage of the late Pleistocene.(2) Since the Holocene epoch,four paleoearthquakes,which happened respectively in 6.12~10.53ka,3.6~5.38ka,1.64~1.93ka and 0.63~1.64ka,ruptured the surface scarps of the Yumen Fault.Overall,the recurrence interval of the paleoseismic events shortens gradually and the activity of the Yumen Fault becomes stronger since the Holocene.Anther characteristic is that every paleoearthquake probably ruptured multiple fault scarps at the same time. 相似文献