Based on the waveform data observed by the regional seismic network of Gansu Province,we calculated the apparent stress of 422 earthquakes with M_L≥ 2. 0 occurring in the surrounding area of the Minxian earthquake fr...Based on the waveform data observed by the regional seismic network of Gansu Province,we calculated the apparent stress of 422 earthquakes with M_L≥ 2. 0 occurring in the surrounding area of the Minxian earthquake from January 2010 to July 2014 and obtained the temporal and spatial variation of apparent stress before and after the Minxian earthquake. Results show that( 1) the high value of apparent stress of earthquakes with M_L≥4. 0 was concentrated in the epicenter area before the Minxian earthquake while that of earthquakes with M_L< 4. 0 was not;( 2) Apparent stress around the epicenter area showed an obvious increasing process before the Minxian earthquake and the increasing process has continued after the main shock,which means that this study area is still in the danger of strong earthquakes.展开更多
On July 22,2013,the Minxian-Zhangxian M_S6.6 earthquake occurred on the east segment of Lintan-Dangchang fault. The analysis of digital elevation and remote sensing imaging shows that the east segment of Lintan-Dangch...On July 22,2013,the Minxian-Zhangxian M_S6.6 earthquake occurred on the east segment of Lintan-Dangchang fault. The analysis of digital elevation and remote sensing imaging shows that the east segment of Lintan-Dangchang fault is still active and the main thrust feature of the fault switches to left lateral slip. With the field research of intensity and damage,several abnormal areas of degree Ⅷ spread in the isoseismal line of degree Ⅶ and some abnormal areas of degree Ⅶ spread in the isoseismal line of degree Ⅵ. These abnormal areas are distributed along the hanging wall of the fault in a width of 2km. The analysis based on the remote sensing and digital elevation model shows that the segment of the Lintan-Dangchang fault south of Minxian mainly slips in left literal. The fault movement made the soil soft in the fault zone. The earthquake motion propagated along the fault zone. Therefore the strong earthquake motion caused foundation failure in the soft soil along the fault zone and the abnormal intense areas of disaster formed.展开更多
In this paper,the seismogenic structures of the Da Qaidam strong earthquakes are preliminarily discussed by using the regional seismotectonic data and focal mechanism solutions. Analysis is done on the temporal and sp...In this paper,the seismogenic structures of the Da Qaidam strong earthquakes are preliminarily discussed by using the regional seismotectonic data and focal mechanism solutions. Analysis is done on the temporal and spatial distribution characteristics of the two strong earthquake sequences in Da Qaidam in combination with the sequence distribution characteristics of the M6. 6 earthquake of 2003 and the five strong earthquakes of about M5. 0 in 2004 in Delingha. At the same time,the regional characteristics of the historical seismic activity are also investigated. Preliminary analysis is done on the influence of the two M8. 0 earthquakes in the past 10 years on this region. Precursory anomalies and their characteristics are discussed in combination with the analysis of the precursor observation data of Qinghai Province.展开更多
针对2013年7月22日甘肃岷县漳县发生的MS6.6地震序列,采用CAP(Cut and Paste)方法反演了岷县漳县6.6级地震及部分强余震的震源机制解。结果显示,6.6级主震最佳双力偶解节面Ⅰ走向189°,倾角51°,滑动角142°;节面Ⅱ参数走向...针对2013年7月22日甘肃岷县漳县发生的MS6.6地震序列,采用CAP(Cut and Paste)方法反演了岷县漳县6.6级地震及部分强余震的震源机制解。结果显示,6.6级主震最佳双力偶解节面Ⅰ走向189°,倾角51°,滑动角142°;节面Ⅱ参数走向305°,倾角61°和滑动角46°,主震为逆冲兼走滑型,矩心震源深度均为7km;8次MS≥3.0余震震源机制解向NE倾的节面Ⅱ的优势倾角约为52°,表现出逆冲分量大的特性。结合震区的活动构造、余震及烈度分布,判定节面Ⅱ代表了相应地震的发震断层面,地震序列震源机制的特性反映了与临潭-宕昌断裂带相似的活动特征,分析认为,岷县漳县6.6级地震的发生与临潭-宕昌断裂的活动可能存在一定的相关性。展开更多
基金sponsored by the regular project of earthquake monitoring and prediction in 2016(16C23ZX327)
文摘Based on the waveform data observed by the regional seismic network of Gansu Province,we calculated the apparent stress of 422 earthquakes with M_L≥ 2. 0 occurring in the surrounding area of the Minxian earthquake from January 2010 to July 2014 and obtained the temporal and spatial variation of apparent stress before and after the Minxian earthquake. Results show that( 1) the high value of apparent stress of earthquakes with M_L≥4. 0 was concentrated in the epicenter area before the Minxian earthquake while that of earthquakes with M_L< 4. 0 was not;( 2) Apparent stress around the epicenter area showed an obvious increasing process before the Minxian earthquake and the increasing process has continued after the main shock,which means that this study area is still in the danger of strong earthquakes.
基金supported by basic scientific research operating expenses of Institute of Earthquake Science,China Earthquake Administration(2012IES010202)
文摘On July 22,2013,the Minxian-Zhangxian M_S6.6 earthquake occurred on the east segment of Lintan-Dangchang fault. The analysis of digital elevation and remote sensing imaging shows that the east segment of Lintan-Dangchang fault is still active and the main thrust feature of the fault switches to left lateral slip. With the field research of intensity and damage,several abnormal areas of degree Ⅷ spread in the isoseismal line of degree Ⅶ and some abnormal areas of degree Ⅶ spread in the isoseismal line of degree Ⅵ. These abnormal areas are distributed along the hanging wall of the fault in a width of 2km. The analysis based on the remote sensing and digital elevation model shows that the segment of the Lintan-Dangchang fault south of Minxian mainly slips in left literal. The fault movement made the soil soft in the fault zone. The earthquake motion propagated along the fault zone. Therefore the strong earthquake motion caused foundation failure in the soft soil along the fault zone and the abnormal intense areas of disaster formed.
基金funded by the project of "Intensive Monitoring and Tracking Studies in the Key Seismic Risk Regions of China in 2011 " of China Earthquake Administration( 2011016301)the‘Comprehensive study of Delingha and Da Qaidam Strong Earthquake Swarms ( 2009A01)of the Earthquake Science Foundation of Qinghai Province,China
文摘In this paper,the seismogenic structures of the Da Qaidam strong earthquakes are preliminarily discussed by using the regional seismotectonic data and focal mechanism solutions. Analysis is done on the temporal and spatial distribution characteristics of the two strong earthquake sequences in Da Qaidam in combination with the sequence distribution characteristics of the M6. 6 earthquake of 2003 and the five strong earthquakes of about M5. 0 in 2004 in Delingha. At the same time,the regional characteristics of the historical seismic activity are also investigated. Preliminary analysis is done on the influence of the two M8. 0 earthquakes in the past 10 years on this region. Precursory anomalies and their characteristics are discussed in combination with the analysis of the precursor observation data of Qinghai Province.
文摘针对2013年7月22日甘肃岷县漳县发生的MS6.6地震序列,采用CAP(Cut and Paste)方法反演了岷县漳县6.6级地震及部分强余震的震源机制解。结果显示,6.6级主震最佳双力偶解节面Ⅰ走向189°,倾角51°,滑动角142°;节面Ⅱ参数走向305°,倾角61°和滑动角46°,主震为逆冲兼走滑型,矩心震源深度均为7km;8次MS≥3.0余震震源机制解向NE倾的节面Ⅱ的优势倾角约为52°,表现出逆冲分量大的特性。结合震区的活动构造、余震及烈度分布,判定节面Ⅱ代表了相应地震的发震断层面,地震序列震源机制的特性反映了与临潭-宕昌断裂带相似的活动特征,分析认为,岷县漳县6.6级地震的发生与临潭-宕昌断裂的活动可能存在一定的相关性。
