In order to study the characteristics of crustal deformation around the epicenter before the 2016 M_S6. 4 Menyuan earthquake,the GPS continuous stations of the period from 2010 to 2016 were selected according to the o...In order to study the characteristics of crustal deformation around the epicenter before the 2016 M_S6. 4 Menyuan earthquake,the GPS continuous stations of the period from 2010 to 2016 were selected according to the observation data of the tectonic environment monitoring network in Chinese Mainland. The deformation characteristics of the crust before the earthquake were discussed through inter-station baseline time series analysis and the strain time series analysis in the epicentral region. The results show that a trend turn of the baseline movement state around the epicenter region occurred after 2014,and the movement after 2014 reflects an obvious decreasing trend of compressional deformation.During this period,the stress field energy was in a certain accumulation state. Since the beginning of 2014,the EW-component linear strain and surface strain rate weakened gradually before the earthquake. It shows that there was an obvious deformation deficit at the epicentral area in the past two years,which indicates that the region accumulated a high degree of strain energy before the earthquake. Therefore,there was a significant background change in the area before the earthquake. The results of the study can provide basic research data for understanding the seismogenic process and mechanism of this earthquake.展开更多
The M_S6. 1 earthquake was a foreshock-mainshock-aftershock type which occurred in the boundary region between Zogang and Markam counties on August 12,2013. Within 9hours before the main shock seven earthquakes of gre...The M_S6. 1 earthquake was a foreshock-mainshock-aftershock type which occurred in the boundary region between Zogang and Markam counties on August 12,2013. Within 9hours before the main shock seven earthquakes of greater than M_L2. 0 occurred,with a maximum of M_L4. 7. In this paper,the earthquake focal mechanism changing process of the Zogang-Markam M_S6. 1 earthquake sequence is studied by calculating the correlation coefficient of body wave spectral amplitudes,and the result shows that the correlation coefficients of spectral amplitude of foreshocks present high value fluctuation with an average value of 0. 86,which shows that the focal mechanism of foreshocks are similar;and the correlation coefficients of spectral amplitude of aftershocks present low value,which shows that the possibility of a large earthquake is not high after a time.展开更多
Based on the digital waveform data recorded by Xinjiang Digital Seismic Network for the Xinyuan-Hejing M_L6.8 earthquake sequences of June 30,2012,this paper analyzes the stress drops of earthquake sequences and the c...Based on the digital waveform data recorded by Xinjiang Digital Seismic Network for the Xinyuan-Hejing M_L6.8 earthquake sequences of June 30,2012,this paper analyzes the stress drops of earthquake sequences and the correlation coefficients of focal mechanisms significant for strong aftershocks.Firstly,the source parameters of the Xinyuan-Hejing M_L6.8 earthquake sequences are obtained by applying the spectrum analysis and the Brunes source model.Then,the correlation coefficients of spectral amplitudes are calculated using the low-frequency spectral amplitude recorded by the same station for the different events.Finally,based on the results of the correlation coefficients of spectral amplitudes,the events with similar focal mechanisms are grouped using the clustering method.The results show that:(1)The stress drop values show a steady trend in the aftershock sequence calm period and the stress drop values show a rise-fall in strong aftershocks.(2)The moving average correlation coefficient of amplitude spectrum begins to spread after the main shock.It shows that the correlation decreases between the main shock and the aftershocks in mechanisms.(3)The results of focal mechanism groups show that the earthquake sequences are mainly strike slips.The stress distribution of the main pressure axis is nearly NS,which is the same as the structural stress field.(4)The magnitude and mechanism show that there is an agreement before the strong aftershock,which shows that the regional stress field is enhanced.展开更多
A Ms6. 8 earthquake occurred on October 5, 2008 in the Wuqia region in Xinjiang. The macroseismic epicenter is situated in the Nula village of the Kyrghyz Republic, 7km southwest of the Wuqia Yierkeshitan Port in Xinj...A Ms6. 8 earthquake occurred on October 5, 2008 in the Wuqia region in Xinjiang. The macroseismic epicenter is situated in the Nula village of the Kyrghyz Republic, 7km southwest of the Wuqia Yierkeshitan Port in Xinjiang. The epicenter intensity is VIII degrees （outside borders）. The areas of intensity VII and VI are 7354km^2 and 1031km^2, respectively. This seismic event is related with movement of the NE-trending Kzikeaerkate fault belt. Buildings in the earthquake-stricken area were damaged or affected to a certain extent by this earthquake, accompanied with some phenomena of geological disaster.展开更多
On July 22, 2013, the Minxian-Zhangxian Ms6. 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-Dang...On July 22, 2013, the Minxian-Zhangxian Ms6. 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
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
Five mobile digital seismic stations were set up by the Earthquake Administration of Yunnan Province near the epicenter of the main shock after the Ning＇er M6. 4 earthquake on June 3, 2007. In this paper, the aftersh...Five mobile digital seismic stations were set up by the Earthquake Administration of Yunnan Province near the epicenter of the main shock after the Ning＇er M6. 4 earthquake on June 3, 2007. In this paper, the aftershock sequence of the Ning＇er M6. 4 earthquake is relocated by using the double difference earthquake location method. The data is from the 5 mobile digital seismic stations and the permanent Simao seismic station. The results show that the length of the aftershock sequence is 40kin and the width is 30km, concentrated obviously at the lateral displacement area between the Pu＇er fault and the NNE-trending faults, with the majority occurring on the Pu＇er fault around the main shock. The depths of aftershocks are from 2kin to 12km, and the predominant distribution is in the depth of 8 ~ 10km. The mean depth is 7. 9kin. The seismic fault dips to the northwest revealed from the profile parallel to this aftershock sequence, which is identical to the dip of the secondary fault of the NE-trending Menglian-Mojiang fault in the earthquake area. There are more earthquakes concentrated in the northwest segment than in the southeast segment, which is perhaps related to the underground medium and faults. The depth profile of the earthquake sequence shows that the relocated earthquakes are mainly located near the Pu＇er fault and the seismic faults dip to the southwest, consistent with the dip of the west branch of the Pu＇er fault. In all, the fault strike revealed by earthquake relocations matches well with the strike in the focal mechanism solutions. The main shock is in the top of the aftershock sequence and the aftershocks are symmetrically distributed, showing that faulting was complete in both the NE and SW directions.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funded by the Earthquake Science and Technology Development Fund of GEA(Grant No.2016M02,2016Y02)the Earthquake Tracking Task of CEA(2017010221)+1 种基金the Fund of Science for Earthquake Resilience,CEA,(XH16038Y,XH14049)Grant of National Natural Science Foundation of China(51408567,41304048)
文摘In order to study the characteristics of crustal deformation around the epicenter before the 2016 M_S6. 4 Menyuan earthquake,the GPS continuous stations of the period from 2010 to 2016 were selected according to the observation data of the tectonic environment monitoring network in Chinese Mainland. The deformation characteristics of the crust before the earthquake were discussed through inter-station baseline time series analysis and the strain time series analysis in the epicentral region. The results show that a trend turn of the baseline movement state around the epicenter region occurred after 2014,and the movement after 2014 reflects an obvious decreasing trend of compressional deformation.During this period,the stress field energy was in a certain accumulation state. Since the beginning of 2014,the EW-component linear strain and surface strain rate weakened gradually before the earthquake. It shows that there was an obvious deformation deficit at the epicentral area in the past two years,which indicates that the region accumulated a high degree of strain energy before the earthquake. Therefore,there was a significant background change in the area before the earthquake. The results of the study can provide basic research data for understanding the seismogenic process and mechanism of this earthquake.
基金jointly sponsored by the Special Program of Earthquake Science and Technology of Earthquake Administration of Sichuan Province(LY1302) the National Key Technology R&D Program of China(2012BAK19802)
文摘The M_S6. 1 earthquake was a foreshock-mainshock-aftershock type which occurred in the boundary region between Zogang and Markam counties on August 12,2013. Within 9hours before the main shock seven earthquakes of greater than M_L2. 0 occurred,with a maximum of M_L4. 7. In this paper,the earthquake focal mechanism changing process of the Zogang-Markam M_S6. 1 earthquake sequence is studied by calculating the correlation coefficient of body wave spectral amplitudes,and the result shows that the correlation coefficients of spectral amplitude of foreshocks present high value fluctuation with an average value of 0. 86,which shows that the focal mechanism of foreshocks are similar;and the correlation coefficients of spectral amplitude of aftershocks present low value,which shows that the possibility of a large earthquake is not high after a time.
基金sponsored by the Earthquake Situation Tracking Program of 2014 (2014020110)the Science and Technological Fund of Earthquake Administration of Xinjiang Uygur Autonomous Region,China (201402)
文摘Based on the digital waveform data recorded by Xinjiang Digital Seismic Network for the Xinyuan-Hejing M_L6.8 earthquake sequences of June 30,2012,this paper analyzes the stress drops of earthquake sequences and the correlation coefficients of focal mechanisms significant for strong aftershocks.Firstly,the source parameters of the Xinyuan-Hejing M_L6.8 earthquake sequences are obtained by applying the spectrum analysis and the Brunes source model.Then,the correlation coefficients of spectral amplitudes are calculated using the low-frequency spectral amplitude recorded by the same station for the different events.Finally,based on the results of the correlation coefficients of spectral amplitudes,the events with similar focal mechanisms are grouped using the clustering method.The results show that:(1)The stress drop values show a steady trend in the aftershock sequence calm period and the stress drop values show a rise-fall in strong aftershocks.(2)The moving average correlation coefficient of amplitude spectrum begins to spread after the main shock.It shows that the correlation decreases between the main shock and the aftershocks in mechanisms.(3)The results of focal mechanism groups show that the earthquake sequences are mainly strike slips.The stress distribution of the main pressure axis is nearly NS,which is the same as the structural stress field.(4)The magnitude and mechanism show that there is an agreement before the strong aftershock,which shows that the regional stress field is enhanced.
基金sponsored by the Relation between Western Characteristics in Seismic Tectonic Area with Strong Earthquakes in Large Delta of Mid Asia(2008CB425703)Xinjiang Aseismic Design and Prevention Datum and Information Management(200906),China
文摘A Ms6. 8 earthquake occurred on October 5, 2008 in the Wuqia region in Xinjiang. The macroseismic epicenter is situated in the Nula village of the Kyrghyz Republic, 7km southwest of the Wuqia Yierkeshitan Port in Xinjiang. The epicenter intensity is VIII degrees （outside borders）. The areas of intensity VII and VI are 7354km^2 and 1031km^2, respectively. This seismic event is related with movement of the NE-trending Kzikeaerkate fault belt. Buildings in the earthquake-stricken area were damaged or affected to a certain extent by this earthquake, accompanied with some phenomena of geological disaster.
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 Ms6. 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sponsored by the Joint Earthquake Science Foundation,China (200804)
文摘Five mobile digital seismic stations were set up by the Earthquake Administration of Yunnan Province near the epicenter of the main shock after the Ning＇er M6. 4 earthquake on June 3, 2007. In this paper, the aftershock sequence of the Ning＇er M6. 4 earthquake is relocated by using the double difference earthquake location method. The data is from the 5 mobile digital seismic stations and the permanent Simao seismic station. The results show that the length of the aftershock sequence is 40kin and the width is 30km, concentrated obviously at the lateral displacement area between the Pu＇er fault and the NNE-trending faults, with the majority occurring on the Pu＇er fault around the main shock. The depths of aftershocks are from 2kin to 12km, and the predominant distribution is in the depth of 8 ~ 10km. The mean depth is 7. 9kin. The seismic fault dips to the northwest revealed from the profile parallel to this aftershock sequence, which is identical to the dip of the secondary fault of the NE-trending Menglian-Mojiang fault in the earthquake area. There are more earthquakes concentrated in the northwest segment than in the southeast segment, which is perhaps related to the underground medium and faults. The depth profile of the earthquake sequence shows that the relocated earthquakes are mainly located near the Pu＇er fault and the seismic faults dip to the southwest, consistent with the dip of the west branch of the Pu＇er fault. In all, the fault strike revealed by earthquake relocations matches well with the strike in the focal mechanism solutions. The main shock is in the top of the aftershock sequence and the aftershocks are symmetrically distributed, showing that faulting was complete in both the NE and SW directions.
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。
