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 relation between plate tectonics and earthquake evolution is analyzed systematically on the basis of 1998-2010 absolute and relative gravity data from the Crustal Movement Observation Network of China. Most earthq...The relation between plate tectonics and earthquake evolution is analyzed systematically on the basis of 1998-2010 absolute and relative gravity data from the Crustal Movement Observation Network of China. Most earthquakes originated in the plate boundary or within the fault zone. Tectonic deformation was most intense and exhibited discontinuity within the tectonically active fault zone because of the differential movement; the stress accumulation produced an abrupt gravity change, which was further enhanced by the earthquake. The gravity data from China's Mainland since 2000 obviously reflected five major earthquakes （Ms 〉 7）, all of which were better reflected than before 2000. Regional gravity anomalies and a gravity gradient change were observed in the area around the epicenter about 2 or 3 years before the earthquake occurred, suggesting that gravity change may be a seismic precursor. Furthermore, in this study, the medium-term predictions of the Ms7.3 Yutian, Ms8.0 Wenchuan, and Ms7.0 Lushan earthquakes are analytically pre- sented and evaluated, especially to estimate location of earthquake.展开更多
The 'earthquake nucleation' is discussed in this paper. The acceleration is a property of the nucleation phase and is a necessary condition of earthquake instability too. If the acceleration property of this n...The 'earthquake nucleation' is discussed in this paper. The acceleration is a property of the nucleation phase and is a necessary condition of earthquake instability too. If the acceleration property of this nucleating process is described by the equation dΩ/dt=C/(tf-t)n, the process can be summarized briefly that the rate of cumulative seismic release is proportional to the inverse power of the remaining time to failure. Based on this principle, the foreshock sequence of the 1975 Haicheng earthquake with Ms7.3, was analysed backward. It is stated clearly that the time-to-failure and magnitude of the mainshock can be predicted successfully if the coefficient r2 attains to the maximum. In the estimation of mainshock time, the error can generally be less than, or far less than,one-half the remaining time between the time of the last used data point and the mainshock.展开更多
By systematically studying seismic strengthening areas before 85 earthquakes with M>=6.0 in China, some results have been extracted. 1) Earthquake active strengthening area exists universally before strong shock o...By systematically studying seismic strengthening areas before 85 earthquakes with M>=6.0 in China, some results have been extracted. 1) Earthquake active strengthening area exists universally before strong shock or great earthquake; 2) The size of the strengthening area and its appearing time will increase when the earthquake magnitude increases; 3) The rate between the size of seismic strengthening area and the size of the source region decreases when earthquake magnitude increases; 4) The appearing time of the earthquake active strengthening region in the eastern part of China is longer than that in the western part of China. The above characteristics have been preliminarily explained qualitatively and half-quantitatively by applying the strong body earthquake generating model and the hard inclusion theory. Then applying the seismic strengthening area, we have obtained long-term predictions of 2 earthquakes, so the seismic strengthening area before strong earthquake or great earthquakes is a universal phenomenon, which has some mechanical base.展开更多
1研究背景。震群是地震活动的一种形式,它的发生和发展与地下物质运动、应力状态、局部地区的构造条件和介质特性均相关(朱传镇等,1981)。受到外部作用后,断层应力增加或发震断层强度降低易导致震群的发生(Shelly et al,2016),其形成可...1研究背景。震群是地震活动的一种形式,它的发生和发展与地下物质运动、应力状态、局部地区的构造条件和介质特性均相关(朱传镇等,1981)。受到外部作用后,断层应力增加或发震断层强度降低易导致震群的发生(Shelly et al,2016),其形成可能受到了大范围构造应力的制约。一些大震来临之前,在相当广阔的区域内,常出现异常的震群活动(朱传镇等,1981;林邦慧等,1994;宋治平等,2001;李冬梅等,2011)。展开更多
以ARCGIS系列软件和VS 2010、SQL Server 2008为平台,通过融合集成活动构造、地震地质和国家基础地理信息,在初步建立的青藏高原东南缘活动构造空间数据库系统基础上,利用地震围空区方法,针对研究区进行区域大地震危险性中长期预测分析...以ARCGIS系列软件和VS 2010、SQL Server 2008为平台,通过融合集成活动构造、地震地质和国家基础地理信息,在初步建立的青藏高原东南缘活动构造空间数据库系统基础上,利用地震围空区方法,针对研究区进行区域大地震危险性中长期预测分析。通过地震信息分时间、分震级的整理与数据输出,分析汇总了11例M≥7.0大震震例的地震空区活动图像以及围空区发震震级与围空区特征与参数。在总结出的经验公式基础上,进一步利用1950—2012年的M≥5.0地震数据,对该区地震围空区的发生与发育状况进行了初步分析与研究,并对未来可能发生大震的发震位置及震级进行了综合分析。研究结果表明,玉树—鲜水河—小江断裂带所围限的青藏高原东南缘地区存在6个比较突出的与区域重要的晚第四纪活动构造带或断裂带相对应的大地震围空区,分别是错那—沃卡裂谷,东喜马拉雅构造结,安宁河—则木河断裂,南汀河断裂—红河断裂,畹町断裂—南汀河断裂,澜沧—景洪断裂东段。这些围空区中主要活动断裂带的晚第四纪活动性与历史地震活动状况也都显示出未来几年至几十年存在发生大地震的危险性,在今后的地震预报工作中应给予特别关注。应用实践表明,通过活动构造数据库的建设可快速有效地实现对区域大地震围空区的动态分析、辨别及大地震危险性初判。展开更多
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jointly funded by the Shanxi Science and Technology Plan Projects(2014K13-04)the Special Earthquake Research Project Grant offered by the China Earthquake Administration(201508009)the Crustal Movement Observation Network of China
文摘The relation between plate tectonics and earthquake evolution is analyzed systematically on the basis of 1998-2010 absolute and relative gravity data from the Crustal Movement Observation Network of China. Most earthquakes originated in the plate boundary or within the fault zone. Tectonic deformation was most intense and exhibited discontinuity within the tectonically active fault zone because of the differential movement; the stress accumulation produced an abrupt gravity change, which was further enhanced by the earthquake. The gravity data from China's Mainland since 2000 obviously reflected five major earthquakes （Ms 〉 7）, all of which were better reflected than before 2000. Regional gravity anomalies and a gravity gradient change were observed in the area around the epicenter about 2 or 3 years before the earthquake occurred, suggesting that gravity change may be a seismic precursor. Furthermore, in this study, the medium-term predictions of the Ms7.3 Yutian, Ms8.0 Wenchuan, and Ms7.0 Lushan earthquakes are analytically pre- sented and evaluated, especially to estimate location of earthquake.
文摘The 'earthquake nucleation' is discussed in this paper. The acceleration is a property of the nucleation phase and is a necessary condition of earthquake instability too. If the acceleration property of this nucleating process is described by the equation dΩ/dt=C/(tf-t)n, the process can be summarized briefly that the rate of cumulative seismic release is proportional to the inverse power of the remaining time to failure. Based on this principle, the foreshock sequence of the 1975 Haicheng earthquake with Ms7.3, was analysed backward. It is stated clearly that the time-to-failure and magnitude of the mainshock can be predicted successfully if the coefficient r2 attains to the maximum. In the estimation of mainshock time, the error can generally be less than, or far less than,one-half the remaining time between the time of the last used data point and the mainshock.
文摘By systematically studying seismic strengthening areas before 85 earthquakes with M>=6.0 in China, some results have been extracted. 1) Earthquake active strengthening area exists universally before strong shock or great earthquake; 2) The size of the strengthening area and its appearing time will increase when the earthquake magnitude increases; 3) The rate between the size of seismic strengthening area and the size of the source region decreases when earthquake magnitude increases; 4) The appearing time of the earthquake active strengthening region in the eastern part of China is longer than that in the western part of China. The above characteristics have been preliminarily explained qualitatively and half-quantitatively by applying the strong body earthquake generating model and the hard inclusion theory. Then applying the seismic strengthening area, we have obtained long-term predictions of 2 earthquakes, so the seismic strengthening area before strong earthquake or great earthquakes is a universal phenomenon, which has some mechanical base.
文摘1研究背景。震群是地震活动的一种形式,它的发生和发展与地下物质运动、应力状态、局部地区的构造条件和介质特性均相关(朱传镇等,1981)。受到外部作用后,断层应力增加或发震断层强度降低易导致震群的发生(Shelly et al,2016),其形成可能受到了大范围构造应力的制约。一些大震来临之前,在相当广阔的区域内,常出现异常的震群活动(朱传镇等,1981;林邦慧等,1994;宋治平等,2001;李冬梅等,2011)。
文摘以ARCGIS系列软件和VS 2010、SQL Server 2008为平台,通过融合集成活动构造、地震地质和国家基础地理信息,在初步建立的青藏高原东南缘活动构造空间数据库系统基础上,利用地震围空区方法,针对研究区进行区域大地震危险性中长期预测分析。通过地震信息分时间、分震级的整理与数据输出,分析汇总了11例M≥7.0大震震例的地震空区活动图像以及围空区发震震级与围空区特征与参数。在总结出的经验公式基础上,进一步利用1950—2012年的M≥5.0地震数据,对该区地震围空区的发生与发育状况进行了初步分析与研究,并对未来可能发生大震的发震位置及震级进行了综合分析。研究结果表明,玉树—鲜水河—小江断裂带所围限的青藏高原东南缘地区存在6个比较突出的与区域重要的晚第四纪活动构造带或断裂带相对应的大地震围空区,分别是错那—沃卡裂谷,东喜马拉雅构造结,安宁河—则木河断裂,南汀河断裂—红河断裂,畹町断裂—南汀河断裂,澜沧—景洪断裂东段。这些围空区中主要活动断裂带的晚第四纪活动性与历史地震活动状况也都显示出未来几年至几十年存在发生大地震的危险性,在今后的地震预报工作中应给予特别关注。应用实践表明,通过活动构造数据库的建设可快速有效地实现对区域大地震围空区的动态分析、辨别及大地震危险性初判。
