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Slip Rate of Yema River–Daxue Mountain Fault since the Late Pleistocene and Its Implications on the Deformation of the Northeastern Margin of the Tibetan Plateau

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Acta Geologica Sinica(English Edition) 2015年第2期89卷 561-574页

作者： LUO Hao HE Wengui yuan daoyang SHAO Yanxiu Key Laboratory of Active Tectonics and Volcano Institute of GeologyChina Earthquake Administration Lanzhou Institute of Seismology China Earthquake Administration Lanzhou National Geophysical Observatory

The slip rate of Yema River-Daxue Mountain fault in the western segment of Qilian Mountains was determined by the dated offset of river risers or gullies. Results indicate that the left-lateral fault slip rate is 2.82± 0.20 mm/a at Dazangdele site, 2.00 ± 0.24 mm/a at Shibandun site, and 0.50± 0.36 and 2.80±0.33 mm/a at two sites in Zhazihu. The ideal average slip rate of the whole fault is 2.81 ± 0.32 mm/a. The lower slip rate confirms part of the displacement of Altyn Tagh fault was transformed into an uplifting of the strap mountains in the western segment of Qilian Mountains, whereas another part transformed into sinistral displacement of Haiyuan fault. This study illustrates that the slip of large strike-slip faults in the northeastern margin of the plateau transforms into crust thickening at the tip of the fault without large-scale propagation to the outer parts of the plateau.

关键词： Slip rate strike-slip fault Yema River-Daxue Mountain fault Altyn Tagh fault,Qilian ranges

The Holocene Activity Evidence of the Yema River-Daxue Mountain Fault in Western Qilian Mountain

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Acta Geologica Sinica(English Edition) 2013年第6期87卷 1569-1584页

作者： LUO Hao HE Wengui yuan daoyang SHAOYanxiu Key Laboratory of Engineering Geomechanics Institute of Geology and Geophysics Chinese Academy of Sciences Earthquake Research Institute of Lanzhou China Earthquake Administration Lanzhou National Geophysical Observatory

Altyn Tagh fault controls the deformation characteristics of the northern margin of the Qinghai-Tibet *** sinistral slip rate of the eastern segment of the fault reduces gradually where the reduction transforms into the deformation within Qilian Mountain,forming a series of thrust faults and strike-slip *** them,the Yema River-Daxue Mountain fault is one of the important structural transform faults in the study *** on the differences of the geometrical characteristics and activities,the fault is divided into four segments,the Yema River segment,the Shibandun segment,the Liushapo segment and the Baishitougou segment,among which the former three are Holocene active faults,and the Baishitougou segment belongs to late Pleistocene *** excavated trenches imply a total of 6 paleoearthquake events,and at least 4 events have occurred during Holocene,whose occurrence times are 8300±700 yr BP,6605±140 yr BP,4540±350 yr BP,2098±47 yr BP,*** recurrence interval is 2600±600 yr BP that is close to the lapsed time of the last one,2098±47 yr BP,which suggests that the Yema River-Daxue Mountain fault is in a high risk of major earthquakes in the *** vertical coseismic displacements of the four Holocene paleoearthquake events are 100 cm,42 cm,40 cm and 50 cm,respectively,the horizontal coseismic displacements are 5 m,4.5-5.5 m,5-8 m and 4-5.5 m,separately,and then the reference magnitude of the paleoearthquake events is conjectured to be M7.6±0.1.

关键词： paleoearthquake earthquake recurrence interval reference magnitude Yema River-Daxue Mountain fault Altyn Tagh fault

Recent Activity of the Badu-Longwei Segment,Guguan-Xiangong Fault in Southern Liupanshan,Constrained by Rhythmic Sediment Lithology and Geomorphic Characteristics

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Acta Geologica Sinica(English Edition) 2015年第4期89卷 1165-1175页

作者： SHI Zhigang yuan daoyang HE Wengui LIU Xingwang WANG Jun Institute of Geology Chinese Academy of Geological Sciences Lanzhou Institute of Seismology China Earthquake Administration Jinchuan Group Co.Ltd.

This study＇s objective was to investigate the Guguan-Xiangong Fault, which lies in the southern Liupanshan area, through satellite image interpretation and field observations. Guguan- Xiangong Fault is divided into five subsegments; among these, the Badu-Longwei segment has been the most recently active. The geomorphic features of the Badu-Longwei segment are clearly displayed, including multiple high fault scarps with fresh bedrock free faces. There is significant evidence for Holocene activity of the three fault sections, located in Renhuashu, Tianjiagou, and Xinjiecun respectively. The three sections feature distinct episodic deposition and fault scratches. Based on 14C- dating and field observations on the three fault sections, two or more paleoearthquakes across the Badu-Longwei fault segment are ascertained, between 5874±116 and 5430±140 a BP, and after 2037±83 a BP respectively. The Badu-Longwei segment of the Guguan-Xiangong Fault is preliminarily extrapolated as the seismogenic structure of the 600 A.D. Qin-Long earthquake.

关键词： Guguan-Xiangong Fault Badu-longwei segment dislocated lanform three sections,rhythmic deposition 14C-dating paleoearthquake

First Discovery of North-South Striking Normal Faults near the Potential Eastern End of Altyn Tagh Fault

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Journal of Earth Science 2018年第1期29卷 182-192页

作者： Bo Zhang daoyang yuan Wengui He Wei Pang Pengtao Wang Ming Wu Lanzhou Institute of Seismology China Earthquake Administration Lanzhou 730000 China Institute of Geology China Earthquake Administration Beijing 100029 China Second Monitoring and Application Center China Earthquake Administration Xi'an 710054 China

The Altyn Tagh fault is the northern boundary of Tibetan Plateau. As one of the most well-known strike-slip fault in the world, great achievements on tectonic deformation and Late Qua- ternary slip rate have been made. However, there is a long-lasting debate on whether the Altyn Tagh fault extends into the Jinta Basin or even eastward. In this paper, we use satellite image interpretation, field investigation, trench excavation, and optical stimulated luminescence dating to study newly found NS striking scarps in the eastern end of Jinta Nan Shan. The results are as follows： firstly, a group of normal faults develop on terrace T2 of Heihe River, the total length amounts to -40 km, total scarp height is 304-5 m; secondly, four paleoseismic events have been interpreted from three trenches, approximate ages of events are 79.97±19.14 ka BP, 62.55±13.10~55.41±10.77 ka BP, before 16.89±2.08 ka BP, 8.52±1.49 ka BP, respectively; thirdly, just like NS normal faults in the western end of Altyn Tagh fault, the newly found NS extensional faults are likely the terminating tectonics of the eastern end of Altyn Tagh fault, the large Altyn Tagh fault may end in the eastern end of Jinta Nan Shan.

关键词： Altyn Tagh fault normal fault Jinta Nan Shan fault Heihe River paleoseismic events.

Characteristics of Paleoseismic Activity Along the Tianqiaogou-Huangyangchuan Fault on the Eastern Section of the Qilian Mountains

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Earthquake Research in China 2005年第2期19卷 139-151页

作者： Zheng Wenjun yuan daoyang He Wengui Lanzhou Base of Earthquake Prediction Institute China Earthquake Administration Lanzhou 730000 China Lanzhou Institute of Seismology China Earthquake Administration Lanzhou 730000 China

The Tianqiaogou-Huangyangchuan fault lies east of the main peak, Lenglongling Mount, in the east part of the Qilian Mountains and is one of the major active faults on the eastern section of the Qilian Mountains. The fault is separated into two segments at Guanjiatai village, the eastern and western segments, and has undergone obvious movement since the Holocene. Six trenches were excavated to study the pa!eoseismic activity along the fault. Integrated and comparative analysis of sediments in the trenches reveals 7 paleoseismic events and a historic earthquake on the fault since the Holocene. Their ages are： event Ⅰ is （10743 ± 343 ）a BP,event Ⅱ （9038 ± 39）a BP, event Ⅲ （7050 ± 577）a BP, event Ⅳ （4847 ± 185）a BP, event Ⅴ（3562 ± 190）a BP, event Ⅵ （2476 ±194） a BP, and event Ⅶ（1505 ± 253）, respectively, and event Ⅷ is the 1927 Gulang Ms8. 0 earthquake. It indicates that the fault might have contributed to the 1927 Gulang Ms8.0 earthquake. The temporal and spatial distribution of the paleoseismic events is relatively uniform and is characterized approximately by a quasiperiodic recurrence.

关键词： Active fault Trench Geological logging Paleoseismic event Gulang Gansu

Seismic Risk Assessment and Maximum Magnitudes of Potential Earthquakes on Active Faults near Lanzhou City

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Earthquake Research in China 2009年第3期23卷 319-327页

作者： Liang Mingjian yuan daoyang Liu Baiehi Lei Zhongsheng Earthquake Administration of Siehuan Province Chengdu 610041 China Lanzhou Institute of Seismology CEALanzhou 730000China Lanzhou Base of Institute of Earthquake Science CEA Lanzhou 730000 China

The Zhuanglang river and Baiyin Baiyangshu river faults are late Quaternary faults near Lanzhou city, which pose a threat to the safety of the city. However, the cause of medium- strong earthquakes along the fault is rather complicated and even uncertain. It is important for us how to assess the magnitudes of maximum potential earthquakes and the seismic risk of the faults. The authors make reference to the method that Wen Xueze, et ai. （2007） developed to assess the magnitudes of maximum potential earthquakes in sub-areas of moderately and weakly active faults in the eastern Chinese Mainland, and brought forward an empirical relationship between the maximum magnitudes Mmax and the at/b values of the sub-areas＇ frequency- magnitude relationships in the Lanzhou area. By using this empirical relationship, the authors have estimated the upper-limits Mu of the Zhuanglang river and Baiyin Baiyangshu river active faults near Lanzhou city as Ms6.9 and 6.3, respectively. In addition, they have assessed the average interval recurrence time and the probabilities of destructive earthquakes on the faults.

关键词： Maximum magnitude of potential earthquake Frequency-magnitude relationship Assessment of earthquake risk Active faults near Lanzhou city

A Preliminary Study of Palaeo-earthquakes on the Maqu Fault of East Kunlun Fault Zone

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Earthquake Research in China 2006年第4期20卷 361-370页

作者： He Wengui Xiong Zhen yuan daoyang Ge Weipeng Liu Xingwang Lanzhou Base of Institute of Earthquake Science CEA Lanzhou 730000 China Lanzhou Institute of Seismology CEA Lanzhou 730000 China Institute of Geophysics CEA Beijing 100081 China

The East Kunlun active fault is an important NWW-trending boundary fault on the northeastern margin of the Qinghai-Xizang (Tibet) Plateau. The Maqu fault is the easternmost segment of the East Kunlun active fault. Based on three trenches, four Holocene palaeo-earthquake events are identified along the Maqu fault. The latest palaeo-earthquake event is (1730±50) ～ (1802±52) a BP, the second is (3736±57) ～ (4641±60) a BP, the third is (8590±70) a BP, and the earliest is (12200±1700) ka BP. The time of the first and second palaeo-earthquake events is more reliable than that of the third and last ones. As a result, the recurrence interval of the palaeo-earthquakes on the easternmost segment of the East Kunlun active fault is approximately 2400 a, and the palaeo-earthquake elapsed time is (1730±50) ～ (1802±52) a BP.

关键词： The east Kunlun active fault Maqu fault Palaeo-earthquake

Discovery of the Surface Rupture Zone on the South of Helishan in Gaotai,Gansu Province

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Earthquake Research in China 2010年第1期24卷 97-105页

作者： Zheng Wenjun Zhang Peizhen yuan daoyang Ge Weipeng Liu Jianhui State Key Laboratory of Earthquake Dynamics Institute of Geology CEA Beijing 100029 China Lanzhou Institute of Seismology China Earthquake Administration Lanzhou 730000 China

According to a new investigation in the northern Hexi corridor,the remains of two surface rupture zones were discovered on the southern margin fault of the Helishan. One rupture has a length of approximately 7km and the other 10km. The two surface rupture zones might have been produced by the latest earthquake event. On the surface rupture is continuous scarp and free face caused by the rupture. The scarp is about 1 ～ 1. 5m high and on some sites,nearly up to 2m. According to the OSL results,the latest T1 terrace and higher flood plain forming in 3000a B. P. are dislocated by the fault. The above reveals the rupture age to be later than the T1 terrace. However,in the historical data and earthquake catalogue,we didn't find related information about the fault and surface rupture in this area. The 180 A. D. Biaoshi M8. 0 earthquake and the 756 A. D. Zhangye-Jiuquan M7. 0 earthquake are documented in historical data. It is inferred by textual research that the two earthquakes are related to the northern marginal fault of Yumushan in the south of the basin. Due to a lack of reliable evidence,there are still many arguments on this inferred conclusion. Thus we hold that the two surface rupture zones were produced by one of the two large earthquakes or other unrecorded historical event. The research on the activity and surface rupture of this fault can offer valuable information for the tectonic study and strong earthquake risk estimates of this region in the future.

关键词： Surface rupture The Helishan southern margin fault The northern Tibet Gaotai, Gansu

A Preliminary Study on the New Activity Features of the Lajishan Mountain Fault Zone in Qinghai Province

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Earthquake Research in China 2005年第4期19卷 391-401页

作者： yuan daoyang Zhang Peizhen Lei Zhongsheng Liu Baichi Liu Xiaolong Lanzhou Base of Institute of Earthquake Prediction CEA Lanzhou 730000 China Institute of Geology China Earthquake Administration Beijing 100029 China

The Lajishan Mountain fault zone consists of two NE_protruding arcuate faults, i.e. the northern and southern margin fault of Lajishan Mountain with the fault length of 230km and 220km respectively. The fault zone is located in the large_scale compressional structure zone and tectonic gradient zone in_between the NNW_trending right_lateral strike_slip Reshui_Riyueshan fault zone and the NWW_trending left_lateral strike_slip northern margin of west Qinling Ranges fault zone is also an important boundary fault zone, separating the Xining_Minhe basin and the Xunhua_Hualong basin at the southern and northern sides of the Lajishan Mountain respectively. Geologic geomorphic evidences of new activity revealed by field investigations indicate that the latest movement of the Lajishan fault zone was in late Epipleistocene (only a few segments were active in early Holocene) and is mainly of compressive thrusting with slightly left_lateral strike_slip component. The above movement has possibly resulted in the occurrence of about 20 moderate earthquakes of magnitude around 5.0. The Lajishan region can therefore be regarded as a seismotectonic window to reflect tectonic movement and earthquake activity.

关键词： Lajishan Mountain Active fault Historical earthquake New activity