Based on the collection of active fault slip rate data of large intra-continental shallow thrust earthquakes occurring in the triangular seismic region of the East Asia continent,a preliminary analysis has been perfor...Based on the collection of active fault slip rate data of large intra-continental shallow thrust earthquakes occurring in the triangular seismic region of the East Asia continent,a preliminary analysis has been performed with results showing that the Wenchuan,Sichuan, China earthquake ( MS = 8.0) of May 12,2008 occurred on the Longmenshan Mountain active fault with an abnormally low slip rate.展开更多
The Xianshuihe fault zone is a seismo-genetic fault zone of left-lateral slip in Southwest China. Since 1725, a total of 59 Ms ≥ 5.0 earthquakes have occurred along this fault zone, including 18 Ms 6.0–6.9 and eight...The Xianshuihe fault zone is a seismo-genetic fault zone of left-lateral slip in Southwest China. Since 1725, a total of 59 Ms ≥ 5.0 earthquakes have occurred along this fault zone, including 18 Ms 6.0–6.9 and eight Ms ≥ 7.0 earthquakes. The seismic risk of the Xianshuihe fault zone is a large and realistic threat to the western Sichuan economic corridor. Based on previous studies, we carried out field geological survey and remote sensing interpretation in the fault zone. In addition, geophysical surveys, trenching and age-dating were conducted in the key parts to better understand the geometry, spatial distribution and activity of the fault zone. We infer to divide the fault zone into two parts： the northwest part and the southeast part, with total eight segments. Their Late Quaternary slip rates vary in a range of 11.5 mm/a –（3±1） mm/a. The seismic activities of the Xianshuihe fault zone are frequent and strong, periodical, and reoccurred. Combining the spatial and temporal distribution of the historical earthquakes, the seismic hazard of the Xianshuihe fault zone has been predicted by using the relationship between magnitude and frequency of earthquakes caused by different fault segments. The prediction results show that the segment between Daofu and Qianning has a possibility of Ms ≥ 7.0 earthquakes, while the segment between Shimian and Luding is likely to have earthquakes of about Ms 7.0. It is suggested to establish a GPS or In SAR-based real-time monitoring network of surface displacement to cover the Xianshuihe fault zone, and an early warning system of earthquakes and post seismic geohazards to cover the major residential areas.展开更多
The Late Quaternary slip rate along the Maqu segment of the eastern Kunlun Fault was estimated using a combination of high-resolution remote sensing imagery interpretation, field observations and differential Global P...The Late Quaternary slip rate along the Maqu segment of the eastern Kunlun Fault was estimated using a combination of high-resolution remote sensing imagery interpretation, field observations and differential Global Positioning System（GPS） measurements of offset river terraces, and 14 C dating of snail shells collected from offset risers. The results show that the left-slip rate along the segment is 3–5 mm/a, and that the vertical slip rate is 0.3–0.5 mm/a. Both the horizontal and vertical slips on the segment remain consistent over a distance of ~100 km. It means that no slip gradient as previously suggested occurred along the Maqu segment, and which thus might behave as an independent seismogenic fault. Judging from multiple relationships among young terrace offsets, we infer that co-seismic surface rupture produced by a characteristic earthquake with a magnitude of Ms7.0–7.5 on the Maqu fault could generate a horizontal slip of 4.5–5 m and a vertical slip of 0.45–0.5 m, with a corresponding ratio（Dh/Dv） of about 9. Two surface rupture events must have occurred over the past 3300 years, the latest one possibly between 1485 cal BP and 1730 cal BP.展开更多
The geometry of the Qianning-Kangding segment of the Xianshuihe fault zone is quite complex, and it is composed of four secondary-faults, i.e., the Yalahe fault, Selaha-Kangding fault, Zeduotang fault and Moxi fault. ...The geometry of the Qianning-Kangding segment of the Xianshuihe fault zone is quite complex, and it is composed of four secondary-faults, i.e., the Yalahe fault, Selaha-Kangding fault, Zeduotang fault and Moxi fault. On this segment, three strong earthquakes with M(7.0 occurred in 1725, 1786 and 1955, respectively. Based on a study of fault landform and geochronology (14C and Thermoluminesense), this paper documents the average horizontal slip rates during the late-Quaternary on all the secondary-faults of the Qianning-Kangding segment as follows: Yalahe fault: (2.0(0.2) mm/a; Selaha-Kangding fault: (5.5(0.6) mm/a; Zeduotang fault: (3.6(0.3) mm/a; Moxi fault: (9.9(0.6) mm/a. The results from the investigation of surface ruptures of historical earthquakes, coseismic-slip and paleo-earthquakes show that the strong-earthquake recurrence intervals are thousands of years on the Yalahe fault, and 230 to 350 years on the Selaha-Kangding and Zeduotang faults. In the next one hundred years, the recurrence of a strong-earthquake on these faults appears impossible. However, the strong-earthquake recurrence interval on the Moxi fault is about 300 years. Up to now, it has been 214 years since the last earthquake (magnitude 7) occurred in 1786, therefore, this fault is now approaching the condition favorable for the next strong earthquake recurrence.展开更多
Recent studies on the Xianshuihe-Xiaojiang fault system suggest that the Late Quaternary strike-slip rate is approximately uniform along the entire length of the fault zone, about 15±2 mm/a. This approximately un...Recent studies on the Xianshuihe-Xiaojiang fault system suggest that the Late Quaternary strike-slip rate is approximately uniform along the entire length of the fault zone, about 15±2 mm/a. This approximately uniform strike slip rate strongly supports the clockwise rotation model of the southeastern Tibetan crust. By approximating the geometry of the arc-shaped Xianshuihe-Xiaojiang fault system as a portion of a small circle on a spherical Earth, the 15±2 mm/a strike slip rate corresponds to clockwise rotation of the Southeastern Tibetan Block at the （5.2±0.7）×10^-7 deg/a angular velocity around the pole （21°N, 88°E） relative to the Northeast Tibetan Block. The approximately uniform strike slip rate along the Xianshuihe-Xiaojiang fault system also implies that the Longmeushan thrust zone is not active, or at least its activity has been very weak since the Late Quaternary. Moreover, the total offset along the Xiaushuihe-Xiaojiang fault system suggests that the lateral extrusion of the Southeastern Tibetan Block relative to Northeastern Tibetan Block is about 160 km and 200-240 km relative to the Tarim-North China block. This amount of lateral extrusion of the Tibetan crust should have accommodated about 13-24% convergence between India and Eurasia based on mass balance calculations. Assuming that the slip rate of 15±2 mm/a is constant throughout the entire history of the Xianshuihe-Xiaojiang fault system, 11±1.5 Ma is needed for the Xianshuihe-Xiaojiang fault system to attain the 160 km of total offset. This implies that left-slip faulting on the Xianshuihe-Xiaojiang fault system might start at 11±1.5 Ma.展开更多
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...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.展开更多
Two sets of active faults,northwest-and northeast-trending faults,are developed in the Chao-shan Plain of East Guangdong.After detailed interpretation of aerophotos,we have found outthat there is the clear phenomenon ...Two sets of active faults,northwest-and northeast-trending faults,are developed in the Chao-shan Plain of East Guangdong.After detailed interpretation of aerophotos,we have found outthat there is the clear phenomenon of sinistral dislocation of drainage system on the Huang-gang-shui fault and part of Fengshun-Shantou fault.Field investigation confirmed that the geo-morphic bodies along the two faults have undergone displacement.Large-scale topographicmapping was made at three displaced sites and samples for age dating were collected from thegeomorphic booies.Calculation indicates that the average rate of sinistral strike-slip movementin the Holocene time amounts to 1.11±0.09～2.69±0.24mm/a along the Huanggangshuifault and 3.26±0.26mm/a along the Fengshun-Shantou fault.These two more active NW-trending faults extend into sea area,where they intersect the NE-trending strongly active Nius-han Island-Xiongdi Isle-Nanpeng Isles fault at a depth of 40～50m in water.The intersection isa location favorable展开更多
Located on the western of Sichuan, the east border of Tibet plateau, Xianshuihe fault is a significant strong earthquake zone. From Huiyuansi pull\|apart basin in Qianning, Xianshuihe fault can be divided two segments...Located on the western of Sichuan, the east border of Tibet plateau, Xianshuihe fault is a significant strong earthquake zone. From Huiyuansi pull\|apart basin in Qianning, Xianshuihe fault can be divided two segments\|NW section and SE section: the construction of the former is single and a main fault; the construction of the latter is complex and composed by three parallel faults, its main fault is named as Selaha—Kangding fault, which distributes along Jinlongsi, Sehala, Mugecuo and Kangding. Yalahe fault, located at the NE direction of the main fault, and Zeduotang fault, located at the SW direction of the main fault, are all secondary faults, which are 9～13km away from the main fault. At the south of Kangding, the segment of Xianshuihe fault is a single main section, called as Moxi fault. On the basis of recent researching results, this paper mainly discusses the slip rate and recurrence interval of strong earthquake of the SE segment (Qianning—Kangding) on Xianshuihe.展开更多
The easternmost Tian Shan lies in eastern Xinjiang, Central Asia. The South Barkol basin fault（SBF） in the northern part of the easternmost Tian Shan is a major tectonic structure in this orogenic region. The late Q...The easternmost Tian Shan lies in eastern Xinjiang, Central Asia. The South Barkol basin fault（SBF） in the northern part of the easternmost Tian Shan is a major tectonic structure in this orogenic region. The late Quaternary activity, paleoseismology, and deformation characteristics of the fault provide important clues for understanding the tectonic process of the eastern Tian Shan orogen and implementing seismic mitigation. Through interpretation of high-resolution satellite images, unmanned aerial vehicle measurements, and detailed geological and geomorphic investigations, we suggest that the fault exhibits clear left-lateral slip along its western segment. Paleoseismic trenches dug near Xiongkuer reveal evidence of six large paleoearthquakes. The four latest paleoearthquakes were dated： the oldest event occurred at 4663 BC–3839 BC. Data on the horizontal offsets along the probable 1842 Barkol earthquake coseismic rupture suggest clear multiple relationships between cumulative offsets and possible ~4 m of coseismic left-lateral slip per event. From the cumulative offsets and 14 C sample ages, we suggest an average Holocene left-lateral slip rate of 2.4–2.8 mm/a on the SBF, accounting for ~80% of lateral deformation within the entire eastern Tian Shan fault system. This result is comparable with the shortening rate of 2–4 mm/a in the whole eastern Tian Shan, indicating an equal role of strike-slip tectonics and compressional tectonics in this orogen, and that the SBF may accommodate substantial lateral tectonic deformation.展开更多
The I ingwu fault is in the eastern boundary of the southern section of Yinchuan graben. It hasa close relation to seismicity in the Lingwu-Wuzhong region.Few researches have been done.In this Paper,on the basis of te...The I ingwu fault is in the eastern boundary of the southern section of Yinchuan graben. It hasa close relation to seismicity in the Lingwu-Wuzhong region.Few researches have been done.In this Paper,on the basis of tee data obtained from field investigation,the activity features inLate Quaternary have been discussed.The vertical displacement and its slip rate have been alsoestimated.The fault is 48km in length,being divided into 3 segments according to geologicaland topographical characteristics.The last rupture along its northern and middle segments wasoccurred in late of Late Pleistocene or early Holocene while that along the southern segmentwas occurred in midle Holocene.The vertical slip rate is estimated as 0.23～025mm/a sinceabout 66ka B.P.based on the vertical displacements of terracesⅠ,Ⅱ and Ⅲ and their ages.展开更多
Offset geomorphic features and deformed late Quaternary strata indicate active deformation along the Langshan-Seertengshan piedmont fault （LSPF）, one of the most active faults in the Hetao fault zone in Inner Mongol...Offset geomorphic features and deformed late Quaternary strata indicate active deformation along the Langshan-Seertengshan piedmont fault （LSPF）, one of the most active faults in the Hetao fault zone in Inner Mongolia, North China. The widespread occurrence of bedrock fault scarps along the LSPF offers excellent opportunity to examine the faulting history. Using cosmogenic ^10Be exposure dating, we measured the exposure ages of the western Langshankou scarp, located in the middle segment of the LSPF. Our data revealed at least two earthquakes that occurred at 22.2±3.3 Ira and 7.2±2.4 ka, respectively. These events are consistent with previous paleoseismic trench studies. The regression of the relationship between the age and sampling height along the scarp yield a fault slip rate of 0.10 ±0.05/-0.06 mm/yr, which is significantly lower than the average post-late Pleistocene fault slip rate of ~1 mm/yr, as estimated from the offset of the T2 terraces by previous studies. This indicates that the slip of the LSPF may have been accommodated by other fault branches.展开更多
Although Yitong graben appears in a rift basin region of Eastern China , it is really not a rift basin but a strike-slip depression . Its features are as follows : (1 ) graben is controlled by both east and west bound...Although Yitong graben appears in a rift basin region of Eastern China , it is really not a rift basin but a strike-slip depression . Its features are as follows : (1 ) graben is controlled by both east and west boundary fauns without any relationship with Mono discontinuity figure ; (2 ) there is no alkalic or calc-alkalic igneous rocks in the layer of early and middle period of graben development ; (3 )west boundary fault is a typical strike-slip fault with some what of arc along the strike , and the fault depression locates in the concave of the arc . East boundary fault is a syndepostional normal fault with translational motion ; (4 ) graben has a long and narrow shape with four sags and three bulges alternating each other ; (5 ) the cross section of graben is asymmetric , high in the east and low in the west ; (6 )the lithofacies changes are quite fast in the cross section . Unconfonnities exist in some area of graben ; (7 )the angle between fault 2 and west boundary fault is a acute angle directing the opposite trend of the west side motion of boundary fault ; (8 )the extensional rate of graben is about 12% , less than the rate in Huabei (19%) and Liaohe (20 %)rift basin.展开更多
祁连山东段发育了多条大型活动断裂,如近东西向展布的天桥沟-黄羊川断裂及北西西向展布的金强河断裂、毛毛山断裂、老虎山断裂等,在马雅雪山北麓、宝泉山隆起北缘还发育了一条整体呈北西-北西西向展布的马雅雪山断裂。其中,前人已对天桥...祁连山东段发育了多条大型活动断裂,如近东西向展布的天桥沟-黄羊川断裂及北西西向展布的金强河断裂、毛毛山断裂、老虎山断裂等,在马雅雪山北麓、宝泉山隆起北缘还发育了一条整体呈北西-北西西向展布的马雅雪山断裂。其中,前人已对天桥沟-黄羊川断裂、金强河断裂、毛毛山断裂、老虎山断裂的晚第四纪活动开展了大量的研究,相比而言,马雅雪山断裂的研究程度还较低,其最新构造活动特征及其与区域主干活动断裂之间的关系等尚不清楚。马雅雪山断裂构成了天祝盆地与南部山体、丘陵的分界线,迹线清晰,断层三角面、断层槽谷多见,局部冲洪积阶地可见线性展布的断层陡坎,显示出断裂在晚第四纪有一定的活动。本研究对马雅雪山断裂西部的金强河段开展了实地调查,重点对马营沟及小黑刺沟2处的阶地断层陡坎开展了高精度地形地貌测量及阶地地貌面定年,对滑动速率进行了厘定。研究结果表明,马雅雪山断裂金强河段晚第四纪活动显著,断裂最近强震活动发生在8.21~3.43 ka BP,晚更新世晚期以来的垂直滑动速率为0.45~0.63 mm/a。展开更多
基金Funded as a sub-project entitled"Tectonic Patterns of Strong Earthquakes in the Central Asia Continent and Its Dynamic Setting(2008CB425703)"within the project"A Study on the Occurrence Mechanism of the Wenchuan Earthquake and Its Large-scale Regional Dynamic Setting" under the National Key Basic R & D Program (973 Program),China
文摘Based on the collection of active fault slip rate data of large intra-continental shallow thrust earthquakes occurring in the triangular seismic region of the East Asia continent,a preliminary analysis has been performed with results showing that the Wenchuan,Sichuan, China earthquake ( MS = 8.0) of May 12,2008 occurred on the Longmenshan Mountain active fault with an abnormally low slip rate.
基金supported by the Special Project of Basic Work of Science and Technology(grant No.2011FY110100-2)the Project of China Geological Survey(grant No.1212010914025 and No.12120113038000)the Project of 12~(th) Five-Year National Sci-Tech Support Plan(grant No.2011BAK12B09)
文摘The Xianshuihe fault zone is a seismo-genetic fault zone of left-lateral slip in Southwest China. Since 1725, a total of 59 Ms ≥ 5.0 earthquakes have occurred along this fault zone, including 18 Ms 6.0–6.9 and eight Ms ≥ 7.0 earthquakes. The seismic risk of the Xianshuihe fault zone is a large and realistic threat to the western Sichuan economic corridor. Based on previous studies, we carried out field geological survey and remote sensing interpretation in the fault zone. In addition, geophysical surveys, trenching and age-dating were conducted in the key parts to better understand the geometry, spatial distribution and activity of the fault zone. We infer to divide the fault zone into two parts： the northwest part and the southeast part, with total eight segments. Their Late Quaternary slip rates vary in a range of 11.5 mm/a –（3±1） mm/a. The seismic activities of the Xianshuihe fault zone are frequent and strong, periodical, and reoccurred. Combining the spatial and temporal distribution of the historical earthquakes, the seismic hazard of the Xianshuihe fault zone has been predicted by using the relationship between magnitude and frequency of earthquakes caused by different fault segments. The prediction results show that the segment between Daofu and Qianning has a possibility of Ms ≥ 7.0 earthquakes, while the segment between Shimian and Luding is likely to have earthquakes of about Ms 7.0. It is suggested to establish a GPS or In SAR-based real-time monitoring network of surface displacement to cover the Xianshuihe fault zone, and an early warning system of earthquakes and post seismic geohazards to cover the major residential areas.
基金support of the Natural Science Foundation of China(41472178)the China Geological Survey projects(1212011120167,12120114002211)
文摘The Late Quaternary slip rate along the Maqu segment of the eastern Kunlun Fault was estimated using a combination of high-resolution remote sensing imagery interpretation, field observations and differential Global Positioning System（GPS） measurements of offset river terraces, and 14 C dating of snail shells collected from offset risers. The results show that the left-slip rate along the segment is 3–5 mm/a, and that the vertical slip rate is 0.3–0.5 mm/a. Both the horizontal and vertical slips on the segment remain consistent over a distance of ~100 km. It means that no slip gradient as previously suggested occurred along the Maqu segment, and which thus might behave as an independent seismogenic fault. Judging from multiple relationships among young terrace offsets, we infer that co-seismic surface rupture produced by a characteristic earthquake with a magnitude of Ms7.0–7.5 on the Maqu fault could generate a horizontal slip of 4.5–5 m and a vertical slip of 0.45–0.5 m, with a corresponding ratio（Dh/Dv） of about 9. Two surface rupture events must have occurred over the past 3300 years, the latest one possibly between 1485 cal BP and 1730 cal BP.
基金Chinese Joint Seismological Science Foundation (95-07-0425).
文摘The geometry of the Qianning-Kangding segment of the Xianshuihe fault zone is quite complex, and it is composed of four secondary-faults, i.e., the Yalahe fault, Selaha-Kangding fault, Zeduotang fault and Moxi fault. On this segment, three strong earthquakes with M(7.0 occurred in 1725, 1786 and 1955, respectively. Based on a study of fault landform and geochronology (14C and Thermoluminesense), this paper documents the average horizontal slip rates during the late-Quaternary on all the secondary-faults of the Qianning-Kangding segment as follows: Yalahe fault: (2.0(0.2) mm/a; Selaha-Kangding fault: (5.5(0.6) mm/a; Zeduotang fault: (3.6(0.3) mm/a; Moxi fault: (9.9(0.6) mm/a. The results from the investigation of surface ruptures of historical earthquakes, coseismic-slip and paleo-earthquakes show that the strong-earthquake recurrence intervals are thousands of years on the Yalahe fault, and 230 to 350 years on the Selaha-Kangding and Zeduotang faults. In the next one hundred years, the recurrence of a strong-earthquake on these faults appears impossible. However, the strong-earthquake recurrence interval on the Moxi fault is about 300 years. Up to now, it has been 214 years since the last earthquake (magnitude 7) occurred in 1786, therefore, this fault is now approaching the condition favorable for the next strong earthquake recurrence.
基金supported mainly by the National Key Basic Research Program(No.2004CB418401)the National Natural Science Foundation of China(grant No.40472109)+1 种基金partly from the Joint Earthquake Science Foundation of China(grant No.105066)the SASAKAWA Scientific Grant from the Japan Science Society.
文摘Recent studies on the Xianshuihe-Xiaojiang fault system suggest that the Late Quaternary strike-slip rate is approximately uniform along the entire length of the fault zone, about 15±2 mm/a. This approximately uniform strike slip rate strongly supports the clockwise rotation model of the southeastern Tibetan crust. By approximating the geometry of the arc-shaped Xianshuihe-Xiaojiang fault system as a portion of a small circle on a spherical Earth, the 15±2 mm/a strike slip rate corresponds to clockwise rotation of the Southeastern Tibetan Block at the （5.2±0.7）×10^-7 deg/a angular velocity around the pole （21°N, 88°E） relative to the Northeast Tibetan Block. The approximately uniform strike slip rate along the Xianshuihe-Xiaojiang fault system also implies that the Longmeushan thrust zone is not active, or at least its activity has been very weak since the Late Quaternary. Moreover, the total offset along the Xiaushuihe-Xiaojiang fault system suggests that the lateral extrusion of the Southeastern Tibetan Block relative to Northeastern Tibetan Block is about 160 km and 200-240 km relative to the Tarim-North China block. This amount of lateral extrusion of the Tibetan crust should have accommodated about 13-24% convergence between India and Eurasia based on mass balance calculations. Assuming that the slip rate of 15±2 mm/a is constant throughout the entire history of the Xianshuihe-Xiaojiang fault system, 11±1.5 Ma is needed for the Xianshuihe-Xiaojiang fault system to attain the 160 km of total offset. This implies that left-slip faulting on the Xianshuihe-Xiaojiang fault system might start at 11±1.5 Ma.
基金the Special Fund for China Earthquake Research (Grant No.201408023)National Natural Science Foundation of China (Grant No.40872132,41030317)Chinese Academy of Sciences Key Project (XDB03020201)
文摘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.
基金This paper presents one of the research results of a key project in Ninth Five-Year Program was supported by China Seismological Bureau grant (95-04-10-04). Institute of Geology, CSB, contribution No.2000B0034.
文摘Two sets of active faults,northwest-and northeast-trending faults,are developed in the Chao-shan Plain of East Guangdong.After detailed interpretation of aerophotos,we have found outthat there is the clear phenomenon of sinistral dislocation of drainage system on the Huang-gang-shui fault and part of Fengshun-Shantou fault.Field investigation confirmed that the geo-morphic bodies along the two faults have undergone displacement.Large-scale topographicmapping was made at three displaced sites and samples for age dating were collected from thegeomorphic booies.Calculation indicates that the average rate of sinistral strike-slip movementin the Holocene time amounts to 1.11±0.09～2.69±0.24mm/a along the Huanggangshuifault and 3.26±0.26mm/a along the Fengshun-Shantou fault.These two more active NW-trending faults extend into sea area,where they intersect the NE-trending strongly active Nius-han Island-Xiongdi Isle-Nanpeng Isles fault at a depth of 40～50m in water.The intersection isa location favorable
文摘Located on the western of Sichuan, the east border of Tibet plateau, Xianshuihe fault is a significant strong earthquake zone. From Huiyuansi pull\|apart basin in Qianning, Xianshuihe fault can be divided two segments\|NW section and SE section: the construction of the former is single and a main fault; the construction of the latter is complex and composed by three parallel faults, its main fault is named as Selaha—Kangding fault, which distributes along Jinlongsi, Sehala, Mugecuo and Kangding. Yalahe fault, located at the NE direction of the main fault, and Zeduotang fault, located at the SW direction of the main fault, are all secondary faults, which are 9～13km away from the main fault. At the south of Kangding, the segment of Xianshuihe fault is a single main section, called as Moxi fault. On the basis of recent researching results, this paper mainly discusses the slip rate and recurrence interval of strong earthquake of the SE segment (Qianning—Kangding) on Xianshuihe.
基金funded by foundation of seismic risk assessment of active faults,China Earthquake Administration(Grant no.1521044025)
文摘The easternmost Tian Shan lies in eastern Xinjiang, Central Asia. The South Barkol basin fault（SBF） in the northern part of the easternmost Tian Shan is a major tectonic structure in this orogenic region. The late Quaternary activity, paleoseismology, and deformation characteristics of the fault provide important clues for understanding the tectonic process of the eastern Tian Shan orogen and implementing seismic mitigation. Through interpretation of high-resolution satellite images, unmanned aerial vehicle measurements, and detailed geological and geomorphic investigations, we suggest that the fault exhibits clear left-lateral slip along its western segment. Paleoseismic trenches dug near Xiongkuer reveal evidence of six large paleoearthquakes. The four latest paleoearthquakes were dated： the oldest event occurred at 4663 BC–3839 BC. Data on the horizontal offsets along the probable 1842 Barkol earthquake coseismic rupture suggest clear multiple relationships between cumulative offsets and possible ~4 m of coseismic left-lateral slip per event. From the cumulative offsets and 14 C sample ages, we suggest an average Holocene left-lateral slip rate of 2.4–2.8 mm/a on the SBF, accounting for ~80% of lateral deformation within the entire eastern Tian Shan fault system. This result is comparable with the shortening rate of 2–4 mm/a in the whole eastern Tian Shan, indicating an equal role of strike-slip tectonics and compressional tectonics in this orogen, and that the SBF may accommodate substantial lateral tectonic deformation.
基金This project was sponsored by the Joint Earthquake Seience Foundation (197013) and the Commission of Science and Technology, Ningxia Hui Autonomous Region, China.
文摘The I ingwu fault is in the eastern boundary of the southern section of Yinchuan graben. It hasa close relation to seismicity in the Lingwu-Wuzhong region.Few researches have been done.In this Paper,on the basis of tee data obtained from field investigation,the activity features inLate Quaternary have been discussed.The vertical displacement and its slip rate have been alsoestimated.The fault is 48km in length,being divided into 3 segments according to geologicaland topographical characteristics.The last rupture along its northern and middle segments wasoccurred in late of Late Pleistocene or early Holocene while that along the southern segmentwas occurred in midle Holocene.The vertical slip rate is estimated as 0.23～025mm/a sinceabout 66ka B.P.based on the vertical displacements of terracesⅠ,Ⅱ and Ⅲ and their ages.
基金supported by the National Natural Science Foundation of China (Grant No.41171001)the 1:50000 Active Fault Mapping of Langshan Piedmont Fault (Grant No.201408023)the Basic Research Business Foundation of the China Earthquake Administration (Grant No.ZDJ2012-02)
文摘Offset geomorphic features and deformed late Quaternary strata indicate active deformation along the Langshan-Seertengshan piedmont fault （LSPF）, one of the most active faults in the Hetao fault zone in Inner Mongolia, North China. The widespread occurrence of bedrock fault scarps along the LSPF offers excellent opportunity to examine the faulting history. Using cosmogenic ^10Be exposure dating, we measured the exposure ages of the western Langshankou scarp, located in the middle segment of the LSPF. Our data revealed at least two earthquakes that occurred at 22.2±3.3 Ira and 7.2±2.4 ka, respectively. These events are consistent with previous paleoseismic trench studies. The regression of the relationship between the age and sampling height along the scarp yield a fault slip rate of 0.10 ±0.05/-0.06 mm/yr, which is significantly lower than the average post-late Pleistocene fault slip rate of ~1 mm/yr, as estimated from the offset of the T2 terraces by previous studies. This indicates that the slip of the LSPF may have been accommodated by other fault branches.
文摘Although Yitong graben appears in a rift basin region of Eastern China , it is really not a rift basin but a strike-slip depression . Its features are as follows : (1 ) graben is controlled by both east and west boundary fauns without any relationship with Mono discontinuity figure ; (2 ) there is no alkalic or calc-alkalic igneous rocks in the layer of early and middle period of graben development ; (3 )west boundary fault is a typical strike-slip fault with some what of arc along the strike , and the fault depression locates in the concave of the arc . East boundary fault is a syndepostional normal fault with translational motion ; (4 ) graben has a long and narrow shape with four sags and three bulges alternating each other ; (5 ) the cross section of graben is asymmetric , high in the east and low in the west ; (6 )the lithofacies changes are quite fast in the cross section . Unconfonnities exist in some area of graben ; (7 )the angle between fault 2 and west boundary fault is a acute angle directing the opposite trend of the west side motion of boundary fault ; (8 )the extensional rate of graben is about 12% , less than the rate in Huabei (19%) and Liaohe (20 %)rift basin.
文摘祁连山东段发育了多条大型活动断裂,如近东西向展布的天桥沟-黄羊川断裂及北西西向展布的金强河断裂、毛毛山断裂、老虎山断裂等,在马雅雪山北麓、宝泉山隆起北缘还发育了一条整体呈北西-北西西向展布的马雅雪山断裂。其中,前人已对天桥沟-黄羊川断裂、金强河断裂、毛毛山断裂、老虎山断裂的晚第四纪活动开展了大量的研究,相比而言,马雅雪山断裂的研究程度还较低,其最新构造活动特征及其与区域主干活动断裂之间的关系等尚不清楚。马雅雪山断裂构成了天祝盆地与南部山体、丘陵的分界线,迹线清晰,断层三角面、断层槽谷多见,局部冲洪积阶地可见线性展布的断层陡坎,显示出断裂在晚第四纪有一定的活动。本研究对马雅雪山断裂西部的金强河段开展了实地调查,重点对马营沟及小黑刺沟2处的阶地断层陡坎开展了高精度地形地貌测量及阶地地貌面定年,对滑动速率进行了厘定。研究结果表明,马雅雪山断裂金强河段晚第四纪活动显著,断裂最近强震活动发生在8.21~3.43 ka BP,晚更新世晚期以来的垂直滑动速率为0.45~0.63 mm/a。
