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Co-Seismic surface rupture and Recurrence Interval of Large Earthquakes along Damaoyaba-Litang Segment of the Litang Fault on the Eastern Margin of the Tibetan Plateau in China

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Journal of Earth Science 2021年第5期32卷 1139-1151页

作者： Shiyuan Wang Rongjun Zhou Mingjian Liang Shao Liu Nina Liu Jianyu Long Sichuan Earthquake Agency^Chengdu 610041 China School of Geological Engineering and Geomatics Chang'an UniversityXi'an 710054China

The Litang fault is a left-lateral secondary shear zone in the Sichuan-Yunnan active block that accommodates the tectonic deformation associated with the eastward extrusion of the upper crust of the Tibetan Plateau. Based on 1 : 50 000 geological mapping of active faults, the Litang fault consists of three geometric segments, the Cuopuhu, Damaoyaba, and Litang segments, in the west of Litang, which are divided by the of Haizi Mountain uplift and the wide-angle bending and branching of the fault near Jinchanggou. This study also identifies the surface rupture of the A.D. 1890 earthquake, which is distributed intermittently along the ~28 km long Damaoyaba segments and ~25 km long Litang segments. The maximum horizontal displacement is 4.1 m along Damaoyaba segments, and 4 m along Litang segments. The rupture involves typical left-lateral shear movement. The two ruptures are divided by discontinuous segments or gaps that are ~18 km long;thus, the total surface rupture is approximately 71 km long. The estimated moment magnitude was M_(w)7.3±0.1. A comprehensive analysis of data obtained from 5 trenches excavated along the Damaoyaba and Litang segments and the trench data by Xu et al.(2005) identifies age constraints of the 4 most recent paleoseimic events occurred B.C. 1468±54–1340±25, B.C. 52±25–A.D. 76±47, A.D. 1115±90, and A.D. 1890, respectively. The recurrence intervals are 1 415±80, 1 104±104, and 775±90 a, which are consistent with quasi-periodic earthquake recurrence behavior. The average recurrence interval is 1 098±112 a.

关键词： Litang fault surface rupture active fault recurrence intervals paleoearthquake eastern Tibetan Plateau

Influence factors on the ground surface rupture zone induced by buried normal fault dislocation

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Earthquake Science 2020年第2期33卷 62-71页

作者： Jianfeng Qi Fengjunnan Liu Xiangyu Yang Yang Zhao School of Urban Geology and Engineering Hebei GEO UniversityShijiazhuang 050031China

The seismic disaster presents a zonal distribution along the fault strike.In this paper,rupture zone of ground surface soil caused by the uniform dislocation,inclined dislocation and warped dislocation of buried normal fault are studied by constituting a three-dimensional finite element model in Automatic Dynamic Incremental Nonlinear Analysis(ADINA).According to the critical value of surface rupture,the variational features and influencing factors of width and starting position of the"avoiding zone"in engineering construction are analyzed by using 96 model calculations.The main results are as follows:(1)Since the rupture zone of the ground surface soil from the point of mechanics is different from the"avoidance zone"from the point of engineering safety,the equivalent plastic strain and the total displacement ratio should be considered to evaluate the effect of the seismic ground movement on buildings.(2)During fault dislocation,plastic failure firstly occurred on the ground surface soil of the footwall side,and then the larger deformation gradually moved to the side of the hanging wall of the fault with the increase of fault displacement.(3)When the vertical displacement of buried fault reaches 3 m,the width of"avoiding zone"in engineering construction varies within the range of 10-90 m,which is most affected by the thickness of overlying soil and the dip angle of the fault.

关键词： buried normal fault surface rupture avoiding zone numerical simulation influence factors

The MS7.1 Yushu earthquake surface rupture and large historical earthquakes on the Garzê-Yushu Fault

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Science Bulletin 2010年第31期 3503-3508页

作者： CHEN LiChun1,WANG Hu1,RAN YongKang1*,SUN XinZhe1,SU GuiWu1,WANG Ji2,TAN XiBin1,LI ZhiMin3 & ZHANG XiaoQing3 1 National Center for Active Fault Studies,Institute of Geology,China Earthquake Administration,Beijing 100029,China 2 China Center for Earthquake Disaster Prevention,Beijing 100029,China 3 Earthquake Administration of Qinghai Province,Xining 810001,China

As revealed by field investigations,the co-seismic surface rupture zone of the 2010 MS7.1 Yushu earthquake,Qinghai is a characteristic sinistral strike-slip feature consisting of three distinct sinistral primary ruptures,with an overall strike of 310°-320° and a total length of 31 km.In addition,an approximately 2-km-long en-echelon tensile fissure zone was found east of Longbao Town;if this site is taken as the north end of the rupture zone,then the rupture had a total length of ～51 km.The surface rupture zone is composed of a series of fissures arranged in an en-echelon or alternating relationship between compressive bulges and tensile fissures,with a measured maximum horizontal displacement of 1.8 m.The surface rupture zone extends along the mapped Garzê-Yushu Fault,which implicates it as the seismogenic fault for this earthquake.Historically,a few earthquakes with a magnitude of about 7 have occurred along the fault,and additionally traces of paleoearthquakes are evident that characterize the short-period recurrence interval of large earthquakes here.Similar to the seismogenic process of the 2008 Wenchuan earthquake,the Yushu earthquake is also due to the stress accumulation and release on the block boundaries resulting from the eastward expansion of Qinghai-Tibet Plateau.However,in contrast with the Wenchuan earthquake,the Yushu earthquake had a sinistral strike-slip mechanism resulting from the uneven eastward extrusion of the Baryan Har and Sichuan-Yunnan fault blocks.

关键词： MS7.1 Yushu earthquake surface rupture large historical earthquakes Garzê-Yushu Fault

Rapid report of the 8 January 2022 M_(S)6.9 Menyuan earthquake,Qinghai,China

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Earthquake Research Advances 2022年第1期2卷 4-14页

作者： Hongfeng Yang Dun Wang Rumeng Guo Mengyu Xie Yang Zang Yue Wang Qiang Yao Chuang Cheng Yanru An Yingying Zhang Earth System Science Programme Faculty of ScienceThe Chinese University of Hong KongShatinNTHong KongChina China University of Geosciences Wuhan WuhanHubeiChina State Key Laboratory of Geodesy and Earth's Dynamic Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhanChina China Earthquake Networks Center China Earthquake AdministrationBeijingChina

The M_(S)6.9 Menyuan earthquake in Qinghai Province,west China is the largest earthquake by far in 2022.The earthquake occurs in a tectonically active region,with a background b-value of 0.87 within 100 km of the epicenter that we derived from the unified catalog produced by China Earthquake Networks Center since late 2008.Field surveys have revealed surface ruptures extending 22 km along strike,with a maximum ground displacement of 2.1 m.We construct a finite fault model with constraints from In SAR observations,which showed multiple fault segments during the Menyuan earthquake.The major slip asperity is confined within 10 km at depth,with the maximum slip of 3.5 m.Near real-time back-projection results of coseismic radiation indicate a northwest propagating rupture that lasted for~10 s.Intensity estimates from the back-projection results show up to a Mercalli scale of IX near the ruptured area,consistent with instrumental measurements and the observations from the field surveys.Aftershock locations(up to January 21,2022)exhibit two segments,extending to~20 km in depth.The largest one reaches M_(S)5.3,locating near the eastern end of the aftershock zone.Although the location and the approximate magnitude of the mainshock had been indicated by previous studies based on paleoearthquake records and seismic gap,as well as estimated stressing rate on faults,significant surfacebreaching rupture leads to severe damage of the high-speed railway system,which poses a challenge in accurately assessing earthquake hazards and risks,and thus demands further investigations of the rupture behaviors for crustal earthquakes.

关键词： surface rupture Coseismic slip Real-time Intensity Aftershock location and statistics Earthquake magnitude forecasting

Segmentations of active normal dip-slip faults around Ordos block according to their surface ruptures in historical strong earthquakes

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Acta Seismologica Sinica(English Edition) 2000年第5期13卷 552-562页

作者：沈德福江娃利肖振敏谢新生 Institute of Crustal Dynamics China Seismological Bureau Beijing China

From the results of researches of active faults in resent years, a correlation analysis between segments of the faults according to surface ruptures in nine historical strong earthquakes occurring in downfaulted system and active structures around Ordos block is conducted in paper. The result shows that there is a good correlation between them, except few individual data that have more uncertain parameters. It shows that intensity and segments of surface ruptures in these strong earthquakes are intrinsically related with the active structures. These strong earthquakes produced stable and unstable rupture boundaries of characteristic-earthquake type and successive occurrence of strong earthquakes on the different boundary faults in the same tectonic unit.

关键词： surface rupture fault segmentation historical strong earthquakes normal dip-slip faults Ordos block

Rapid Identification and Emergency Investigation of surface ruptures and Geohazards Induced by the M_s 7.1 Yushu Earthquake

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Acta Geologica Sinica(English Edition) 2010年第6期84卷 1315-1327页

作者： ZHANG Yongshuang YAO Xin XIONG Tanyu MA Yinsheng HU Daogong YANG Nong GUO Changbao Key Laboratory of Neotectonic Movement and Geohazard MLR Beo＇ing 100081 China Institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China

The rapid identification based on InSAR technology was proved to be effective in our emergency investigation of surface ruptures and geohazards induced by the Yushu earthquake.The earthquake-generating fault of the Yushu earthquake is the Yushu section of the Garze-Yushu faults zone.It strikes NWW-NW,23 km long near the Yushu County seat,dominated by left-lateral strike slip,and appearing as a surface rupture zone.The macroscopic epicenter is positioned at Guo-yang-yan -song-duo of Gyegu Town（33°03＇11＂N,96°51＇26＂E）,where the co-seismic horizontal offset measured is 1.75 m.Geohazards induced by the Yushu earthquake are mainly rockfalls,landslides,debris flows, and unstable slopes.They are controlled by the earthquake-generating fault and are mostly distributed along it.There are several geohazard chains having been established,such as earthquake,canal damage,soil liquefying,landslide-debris flow,earthquake,soil liquefying,roadbed deformation,etc.In order to prevent seismic hazards,generally,where there is a visible surface rupture induced by the Yushu earthquake,reconstruction should be at least beyond 20 m,on each side,from it.Sufficient attention should also be given to potential geohazards or geohazard chains induced by the earthquake.

关键词： Yushu earthquake InSAR surface rupture macroscopic epicenter earthquake geohazard

Rock avalanches triggered by oblique-thrusting during the 1 2 May 2008 Ms 8.0 Wenchuan earthquake,China

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Rock avalanches triggered by oblique-thrusting during the 1 ...

Resonance effect existence or not for landslides triggered by 2008 Wenchuan earthquake:A reply to the comment by Drs.Xu Chong and Xu Xiwei

中国科学院地质与地球物理研究所第11届（2011年度）...

作者： F.C.Dai~(a,*),X.B.Tu~a,C.Xu~a,Q.M.Gong~b,X.Yao~c a Institute of Geology and Geophysics,Chinese Academy of Sciences,P.O.Box 9825,Beijing 100029,PR China b College of Architecture and Civil Engineering,Beijing University of Technology,Beijing 100022,PR China c Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,PR China

The 12 May 2008 Wenchuan earthquake(Ms 8.0) triggered over 56,000 landslides over a broad area, including shallow,disrupted landslides,rock falls,deep-seated landslides,and rock avalanches.Among these landslides,rock avalanches are of great concern because of the large volume of displaced material,the long runout distance and the resulting fatalities.In this paper,some rock avalanches(including the Woqian,the Tangjiawan,the Hongyancun,the Xiejiadianzi,and the Shuimogou rock avalanches) were selected for detailed study.Mapping of coseismic surface rupture has been carried out at regional and site scales.The minor scarps or stepped topographic features observed at the source areas of the rock avalanches correspond spatially to the surface rupture,indicating that they should be created by thrusting of a fault that ruptured during the 2008 Wenchuan earthquake.Avalanche deposits of some rock avalanches are shifted northeastward,the same direction with the strike-slip of the fault rupture,compared with the sources of the rock avalanches,indicating that the component of strike-slip of the fault rupture exerted a horizontal initial velocity on the failed mass.For the Woqian rock avalanche,the source rock on the hanging wall was pushed northeastward,creating a hummocky topographic feature because of the right-lateral slip of the fault rupture.These rock avalanches are,therefore,triggered by oblique-thrust faulting.In addition,the source rock mass was of poor quality resulting from the shearing and brecciation associated with fault movement in history,rendering the rock slopes prone to failure and contributing to the high degree of disintegration of the failed rock mass.

关键词： Wencliuan earthquake Rock avalanches surface rupture Oblique-thrust faulting

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Resonance effect existence or not for landslides triggered b...

A new fault rupture scenario for the 2003 Mw 6.6 Bam earthquake,SE Iran:Insights from the high-resolution QuickBird imagery and field observations

中国科学院地质与地球物理研究所2012年度（第12届）...

作者： Shengwen Qi Qiang Xu Hengxing Lan Bing Zhang Jianyou Liu Key Lab.of Engineering Geomechanics Institute of Geology and GeophysicsChinese Academy of Sciences State Key Lab.of Geo-hard Prevention and Geo-environment Protection Chengdu University of Technology State Key Laboratory of Resources and Environmental System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences Centre for Earth Observation and Digital Earth Chinese Academy of Sciences

We are very grateful to receive these remarks about our paper.In our paper,we found that more landslides occurred in the block located between F2 and F3 than that in the hanging wall of the seismogenic fault of F2(see Figure 6 in our paper) based on a database of 13,085 landslides in a distributed area of 418.85 km(the smallest landslide in this inventory covers an area of 306.5 m),and we thought that this is maybe the result of resonance of the block between F2 and F3 under the combination movement of the seismogenic faults F2 and F3 and then the motion there is amplified.In their discussion,Xu and Xu (2012)point out that there is no resonance effect of the block between F2 and F3 combination movement,or the resonance effect is rather

关键词： Coseismic landslide Wenchuan earthquake coseismic fault surface rupture

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A new fault rupture scenario for the 2003 Mw 6.6 Bam earthqu...