The present-day tectonic activities on the northeastern margin of the Pamir Plateau are mainly E-W oriented extensions, among which the Kongur Extensional System(KES) plays an important role in the internal expansion ...The present-day tectonic activities on the northeastern margin of the Pamir Plateau are mainly E-W oriented extensions, among which the Kongur Extensional System(KES) plays an important role in the internal expansion of the Pamir. As the largest earthquake since Taxkorgan earthquakes in 1895 and 1896, the Aketao earthquake occurred on the Muji fault on the northern portion of the KES in 2016. Since then, the trend of seismic activities along the KES has been paid much attention to. Based on the visco elastic layered lithosphere model, we calculate the co-seismic and post-seismic stress changes caused by five historical earthquakes on the KES and its adjacent areas since 1895, and analyze the interaction among strong earthquakes. The results show that all of the historical earthquakes after 1895 occurred in the areas where the co-seismic and post-seismic Coulomb stress increased. Coulomb stress loading at the hypocenters of the 1896 Taxkorgan earthquake, the 1974 Markansu earthquake and the 2016 Aketao earthquake were 0.251 MPa, 0.013 MPa and 0.563 MPa, respectively. The three earthquakes were catalyzed by such variations. The historical earthquakes increased the stress state on most segments of the Southern Kungai Mountain fault and Kongur fault along the KES. In particular, we can identify 2 visible earthquake gaps with increasing seismic hazard formed on the Qimugan segment and Bulunkou segment of the KES. The Qimugan section and the Bulunkou section are located at the fault transition zone with concentrated stress and high extension rate, so great attention should be paid to their seismic hazard at present day.展开更多
In this study,data from the Xinjiang regional network and IRIS shared global stations are used to relocate the Akto MS6. 7 earthquake sequence on November 25,2016 by using double difference location method. Three eart...In this study,data from the Xinjiang regional network and IRIS shared global stations are used to relocate the Akto MS6. 7 earthquake sequence on November 25,2016 by using double difference location method. Three earthquakes of MS4. 8,MS6. 7 and MS5. 0 are inverted by using the g CAP method,and the focal mechanism solutions are obtained.According to the results of relocating,the location of the main shock is 39. 22°N,73. 98°E,the distribution of the earthquake sequence is about 70 km in length,and the focal depth is mainly within the range of 5-20 km. The plane and depth profiles of the earthquake sequence show that aftershocks extended in SEE direction after the main shock and the dip angle of fault plane is steep. Focal mechanism results show that the three earthquakes are characterized by strike-slip movement. Based on the results of field geological investigation,it is inferred that the seismogenic fault of the Akto earthquake is Muji fault,which is located at the northernmost end of the Kongur extensional system.The possible cause of this earthquake is that the Indian Plate continues to push northward,and during this compression process,the Indian Plate is affected by the clockwise rotation of the Tarim basin,which causes the accumulation of right-lateral action of the Muji fault,resulting in this earthquake.展开更多
基金funded by the Spark Program of Earthquake Technology of CEA(XH17023Y)The National Natural Science Foundation of China(41604079,41504011,41574017,41541029)the Science and Technology Partnership Program of Shanghai Cooperation Organization(2017E01030)
文摘The present-day tectonic activities on the northeastern margin of the Pamir Plateau are mainly E-W oriented extensions, among which the Kongur Extensional System(KES) plays an important role in the internal expansion of the Pamir. As the largest earthquake since Taxkorgan earthquakes in 1895 and 1896, the Aketao earthquake occurred on the Muji fault on the northern portion of the KES in 2016. Since then, the trend of seismic activities along the KES has been paid much attention to. Based on the visco elastic layered lithosphere model, we calculate the co-seismic and post-seismic stress changes caused by five historical earthquakes on the KES and its adjacent areas since 1895, and analyze the interaction among strong earthquakes. The results show that all of the historical earthquakes after 1895 occurred in the areas where the co-seismic and post-seismic Coulomb stress increased. Coulomb stress loading at the hypocenters of the 1896 Taxkorgan earthquake, the 1974 Markansu earthquake and the 2016 Aketao earthquake were 0.251 MPa, 0.013 MPa and 0.563 MPa, respectively. The three earthquakes were catalyzed by such variations. The historical earthquakes increased the stress state on most segments of the Southern Kungai Mountain fault and Kongur fault along the KES. In particular, we can identify 2 visible earthquake gaps with increasing seismic hazard formed on the Qimugan segment and Bulunkou segment of the KES. The Qimugan section and the Bulunkou section are located at the fault transition zone with concentrated stress and high extension rate, so great attention should be paid to their seismic hazard at present day.
基金Co-sponsored by the Seismological Science and Technology Spark Program(XH19053)the Regular Project “Operation and Maintenance of the National Automatic Reporting Center(CSN/GSN)and System Optimization”
文摘In this study,data from the Xinjiang regional network and IRIS shared global stations are used to relocate the Akto MS6. 7 earthquake sequence on November 25,2016 by using double difference location method. Three earthquakes of MS4. 8,MS6. 7 and MS5. 0 are inverted by using the g CAP method,and the focal mechanism solutions are obtained.According to the results of relocating,the location of the main shock is 39. 22°N,73. 98°E,the distribution of the earthquake sequence is about 70 km in length,and the focal depth is mainly within the range of 5-20 km. The plane and depth profiles of the earthquake sequence show that aftershocks extended in SEE direction after the main shock and the dip angle of fault plane is steep. Focal mechanism results show that the three earthquakes are characterized by strike-slip movement. Based on the results of field geological investigation,it is inferred that the seismogenic fault of the Akto earthquake is Muji fault,which is located at the northernmost end of the Kongur extensional system.The possible cause of this earthquake is that the Indian Plate continues to push northward,and during this compression process,the Indian Plate is affected by the clockwise rotation of the Tarim basin,which causes the accumulation of right-lateral action of the Muji fault,resulting in this earthquake.
