The Chenghai fault zone is located in the Sichuan–Yunnan rhombus block,which is surrounded by the Honghe River,Xianshuihe–Xiaojiang,and Jinsha River fault zones.As a mid-continental active fault,it is one of the mos...The Chenghai fault zone is located in the Sichuan–Yunnan rhombus block,which is surrounded by the Honghe River,Xianshuihe–Xiaojiang,and Jinsha River fault zones.As a mid-continental active fault,it is one of the most important seismogenic fractures in the southeast margin of the Tibetan Plateau.Geological seismic study is an important supplement to the historical seismic record;therefore,identification of paleoearthquake events in this region is of great significance to reveal the pattern and mechanism of earthquake development.In this study,detailed investigation has been carried out on the earthquake traces that formed in the Quaternary sediments in the Jinsha River section of the Chenghai fault zone,and samples for dating chronology testing were also collected.Many paleoearthquake traces were discovered in the field,including earthquake fissions,dammed lake sediments and landslides,earthquake-generated rock falls,seismic faults,and sand liquefaction veins.The collected samples were tested using optically stimulated luminescence,electron-spin resonance,and U-series methods.A total of 68 chronological samples were dated,combined with the results of field investigations,and 10 large paleoearthquake events were discovered in this region since 500 ka,which are at approximately 450,400,345,300,250,190,155,105,75,and 25 ka.Ten tectonic activity periods that produced multiple paleoearthquake events were identified since 500 ka.This study identifies paleoearthquake events in longer scales,larger spaces,and more extensive sediments,which provides new perspectives and new ideas for paleoearthquake research.展开更多
The 1515 M7/4 Yongsheng earthquake is the strongest earthquake historically in northwest Yunnan. However, its time, magnitude and the seismogenic fault have long been a topic of dispute. In order to accurately define ...The 1515 M7/4 Yongsheng earthquake is the strongest earthquake historically in northwest Yunnan. However, its time, magnitude and the seismogenic fault have long been a topic of dispute. In order to accurately define those problems, a 1：50000 active tectonic mapping was carried out along the northern segment of the Chenghai-Binchuan fault zone. The result shows that there is an at least 25 km- long surface rupture and a series of seismic landslides distributed along the Jinguan fault and the Chenghai fault. Radiocarbon dating of the 14C samples indicates that the surface rupture should be a part of the deformation zone caused by the Yongsheng earthquake in the year 1515. The distribution characteristics of this surface rupture indicate that the macroscopic epicenter of the 1515 Yongsheng earthquake may be located near Hongshiya, and the seismogenic fault of this earthquake is the Jinguan- Chenghai fault, the northern part of the Chenghai-Binchuan fault zone. Striations on the surface rupture show that the latest motion of the fault is normal faulting. The maximum co-seismic vertical displacement can be 3.8 m, according to the empirical formula for the fault displacement and moment magnitude relationship, the moment magnitude of the Yongsheng earthquake was Mw 7.3-7.4. Furthermore, combining published age data with the 14C data in this paper reveals that at least four large earthquakes of similar size to the 1515 Yongsheng earthquake, have taken place across the northern segment of the Chenghai-Binchuan fault zone since 17190~50 yr. BP. The in-situ recurrence interval of Mw 7.3-7.4 characteristic earthquakes in Yongsheng along this fault zone is possibly on the order of 6 ka.展开更多
青藏高原东南部边缘的程海-宾川断裂带是一条正断与左旋走滑运动兼具的复合型活动断裂,起着调节青藏高原内部物质向东挤出的重要作用,并控制着区域的主要强震活动.基于GIS(Geographic Information System)技术,利用遥感影像和DEM(Digita...青藏高原东南部边缘的程海-宾川断裂带是一条正断与左旋走滑运动兼具的复合型活动断裂,起着调节青藏高原内部物质向东挤出的重要作用,并控制着区域的主要强震活动.基于GIS(Geographic Information System)技术,利用遥感影像和DEM(Digital Elevation Model)数据提取该区的关键构造地貌信息,对其第四纪分段活动性及特征进行了分析探讨.结果表明,程海-宾川断裂带的第四纪活动具有明显的分段性及空间差异性.其北段的金官-程海盆地主边界断层以正断层活动性质为主,并具有整个断裂带上最高的垂直活动速率;中段的期纳断裂以左旋走滑运动为主,且具有最高的走滑活动速率;南段宾川盆地东缘边界断裂也以正断层活动为主,但垂直活动速率略低于北段.总体上看,程海-宾川断裂带第四纪期间的垂直活动性由北往南降低,水平走滑活动性由中段往南北两端降低.在活动强度方面,程海-宾川断裂带百万年尺度的长期活动速率一直保持着较为稳定的状态,垂直活动速率主要集中在0.09~0.69mm/a,水平走滑速率在0.20~1.40mm/a.整体而言,程海-宾川断裂带中多数断裂的第四纪活动性以“中等”和“弱”为主.但历史地震活动表明,其不同段落上的未来强震活动趋势值得关注,尤其是历史强震活动相对空缺的中南段.展开更多
基金supported by Geological Survey Program(Grant No.12120114001501,DD20160306 and DD20160268)the National Natural Science Foundation of China(Grant No.41772383 and 41571013)。
文摘The Chenghai fault zone is located in the Sichuan–Yunnan rhombus block,which is surrounded by the Honghe River,Xianshuihe–Xiaojiang,and Jinsha River fault zones.As a mid-continental active fault,it is one of the most important seismogenic fractures in the southeast margin of the Tibetan Plateau.Geological seismic study is an important supplement to the historical seismic record;therefore,identification of paleoearthquake events in this region is of great significance to reveal the pattern and mechanism of earthquake development.In this study,detailed investigation has been carried out on the earthquake traces that formed in the Quaternary sediments in the Jinsha River section of the Chenghai fault zone,and samples for dating chronology testing were also collected.Many paleoearthquake traces were discovered in the field,including earthquake fissions,dammed lake sediments and landslides,earthquake-generated rock falls,seismic faults,and sand liquefaction veins.The collected samples were tested using optically stimulated luminescence,electron-spin resonance,and U-series methods.A total of 68 chronological samples were dated,combined with the results of field investigations,and 10 large paleoearthquake events were discovered in this region since 500 ka,which are at approximately 450,400,345,300,250,190,155,105,75,and 25 ka.Ten tectonic activity periods that produced multiple paleoearthquake events were identified since 500 ka.This study identifies paleoearthquake events in longer scales,larger spaces,and more extensive sediments,which provides new perspectives and new ideas for paleoearthquake research.
基金supported by National Natural Science foundation of China(grants No.41571013)China Geology Survey project(grants No.DD20160268)Institute of Geomechanics,Chinese academy of geological sciences basal research fund(grants No.DZLXJK201702)
文摘The 1515 M7/4 Yongsheng earthquake is the strongest earthquake historically in northwest Yunnan. However, its time, magnitude and the seismogenic fault have long been a topic of dispute. In order to accurately define those problems, a 1：50000 active tectonic mapping was carried out along the northern segment of the Chenghai-Binchuan fault zone. The result shows that there is an at least 25 km- long surface rupture and a series of seismic landslides distributed along the Jinguan fault and the Chenghai fault. Radiocarbon dating of the 14C samples indicates that the surface rupture should be a part of the deformation zone caused by the Yongsheng earthquake in the year 1515. The distribution characteristics of this surface rupture indicate that the macroscopic epicenter of the 1515 Yongsheng earthquake may be located near Hongshiya, and the seismogenic fault of this earthquake is the Jinguan- Chenghai fault, the northern part of the Chenghai-Binchuan fault zone. Striations on the surface rupture show that the latest motion of the fault is normal faulting. The maximum co-seismic vertical displacement can be 3.8 m, according to the empirical formula for the fault displacement and moment magnitude relationship, the moment magnitude of the Yongsheng earthquake was Mw 7.3-7.4. Furthermore, combining published age data with the 14C data in this paper reveals that at least four large earthquakes of similar size to the 1515 Yongsheng earthquake, have taken place across the northern segment of the Chenghai-Binchuan fault zone since 17190~50 yr. BP. The in-situ recurrence interval of Mw 7.3-7.4 characteristic earthquakes in Yongsheng along this fault zone is possibly on the order of 6 ka.
文摘青藏高原东南部边缘的程海-宾川断裂带是一条正断与左旋走滑运动兼具的复合型活动断裂,起着调节青藏高原内部物质向东挤出的重要作用,并控制着区域的主要强震活动.基于GIS(Geographic Information System)技术,利用遥感影像和DEM(Digital Elevation Model)数据提取该区的关键构造地貌信息,对其第四纪分段活动性及特征进行了分析探讨.结果表明,程海-宾川断裂带的第四纪活动具有明显的分段性及空间差异性.其北段的金官-程海盆地主边界断层以正断层活动性质为主,并具有整个断裂带上最高的垂直活动速率;中段的期纳断裂以左旋走滑运动为主,且具有最高的走滑活动速率;南段宾川盆地东缘边界断裂也以正断层活动为主,但垂直活动速率略低于北段.总体上看,程海-宾川断裂带第四纪期间的垂直活动性由北往南降低,水平走滑活动性由中段往南北两端降低.在活动强度方面,程海-宾川断裂带百万年尺度的长期活动速率一直保持着较为稳定的状态,垂直活动速率主要集中在0.09~0.69mm/a,水平走滑速率在0.20~1.40mm/a.整体而言,程海-宾川断裂带中多数断裂的第四纪活动性以“中等”和“弱”为主.但历史地震活动表明,其不同段落上的未来强震活动趋势值得关注,尤其是历史强震活动相对空缺的中南段.
