Field observation shows that the surface rupture of the Kunlun Mountains Pass M_S 8.1 earthquake is about 426km long, and the maximum sinistral displacement is about 6m. Distribution of horizontal displacement along t...Field observation shows that the surface rupture of the Kunlun Mountains Pass M_S 8.1 earthquake is about 426km long, and the maximum sinistral displacement is about 6m. Distribution of horizontal displacement along the surface ruptures is markedly controlled by fault structure. The rupture length of this earthquake is significantly longer than statistic value. In this paper, using the method of “ultimate linear strain", we discussed the independency and integrality of the whole rupture zone and rupture segments of the Kunlun Mountains Pass earthquake by comparing with some large earthquakes on strike-slip faults on the Chinese continent. The conclusion is that the Kunlun Mountains Pass earthquake consists of successively triggered multiple earthquake events, other than a single earthquake event.展开更多
According to volume 18(Xuanzong Ji Tang)of the historical book entitled the Old Book of Tang,the Hetao area of Inner Mongolia experienced a large earthquake in AD 849.However,previous work on that earthquake contains ...According to volume 18(Xuanzong Ji Tang)of the historical book entitled the Old Book of Tang,the Hetao area of Inner Mongolia experienced a large earthquake in AD 849.However,previous work on that earthquake contains many discrepancies regarding its epicenter location,magnitude,deaths,and intensity.While exploring active faults in Baotou City,the present authors mapped the Daqing Mountain piedmont fault geologically.Based on previous work,several seismic deformation traces of more than 1000 years ago were found,and dating tests were conducted.The research showed the Daqing Mountain piedmont fault zone to be the seismogenic structure of the AD 849 earthquake.The length of earthquake surface rupture zone was around 80 km,and the macro epicenter was located in the active fault.The deformation center was located at 40.6°N,110.2°E.By collecting and analyzing more historical data about the AD 849 earthquake,reinterpreting some existing historical data,and re-examining the contradictory numbers of deaths in the historical data,the present analysis concludes that around 10,000 people were dead.It is suggested that this earthquake had a magnitude of 7½.According to the revised seismic parameters and the paleoearthquake recurrence period of the Daqing Mountain piedmont fault,the boundary of some potential seismic sources zone in the Baotou area are adjusted and the recurrence period of M8 and M7.5 are re-calculated.展开更多
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 ruptu...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.展开更多
文摘Field observation shows that the surface rupture of the Kunlun Mountains Pass M_S 8.1 earthquake is about 426km long, and the maximum sinistral displacement is about 6m. Distribution of horizontal displacement along the surface ruptures is markedly controlled by fault structure. The rupture length of this earthquake is significantly longer than statistic value. In this paper, using the method of “ultimate linear strain", we discussed the independency and integrality of the whole rupture zone and rupture segments of the Kunlun Mountains Pass earthquake by comparing with some large earthquakes on strike-slip faults on the Chinese continent. The conclusion is that the Kunlun Mountains Pass earthquake consists of successively triggered multiple earthquake events, other than a single earthquake event.
基金supported by a subproject of the strategic leading science and technology project(A)of the Chinese Academy of Sciences(No.XDA20070302)we thank the reviewers and editors for their suggestions and opinions.
文摘According to volume 18(Xuanzong Ji Tang)of the historical book entitled the Old Book of Tang,the Hetao area of Inner Mongolia experienced a large earthquake in AD 849.However,previous work on that earthquake contains many discrepancies regarding its epicenter location,magnitude,deaths,and intensity.While exploring active faults in Baotou City,the present authors mapped the Daqing Mountain piedmont fault geologically.Based on previous work,several seismic deformation traces of more than 1000 years ago were found,and dating tests were conducted.The research showed the Daqing Mountain piedmont fault zone to be the seismogenic structure of the AD 849 earthquake.The length of earthquake surface rupture zone was around 80 km,and the macro epicenter was located in the active fault.The deformation center was located at 40.6°N,110.2°E.By collecting and analyzing more historical data about the AD 849 earthquake,reinterpreting some existing historical data,and re-examining the contradictory numbers of deaths in the historical data,the present analysis concludes that around 10,000 people were dead.It is suggested that this earthquake had a magnitude of 7½.According to the revised seismic parameters and the paleoearthquake recurrence period of the Daqing Mountain piedmont fault,the boundary of some potential seismic sources zone in the Baotou area are adjusted and the recurrence period of M8 and M7.5 are re-calculated.
基金supported by the management and other functions of the Institute of Geology,CEA
文摘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.
