The 2018,Songyuan,Jilin M_S5. 7 earthquake occurred at the intersection of the FuyuZhaodong fault and the Second Songhua River fault. The moment magnitude of this earthquake is M_W5. 3,the centroid depth by the wavefo...The 2018,Songyuan,Jilin M_S5. 7 earthquake occurred at the intersection of the FuyuZhaodong fault and the Second Songhua River fault. The moment magnitude of this earthquake is M_W5. 3,the centroid depth by the waveform fitting is 12 km,and it is a strike-slip type event. In this paper,with the seismic phase data provided by the China Earthquake Network, the double-difference location method is used to relocate the earthquake sequence,finally the relocation results of 60 earthquakes are obtained. The results show that the aftershock zone is about 4. 3km long and 3. 1km wide,which is distributed in the NE direction. The depth distribution of the seismic sequence is 9km-10 km. 1-2 days after the main shock,the aftershocks were scattered throughout the aftershock zone,and the largest aftershock occurred in the northeastern part of the aftershock zone. After 3-8 days,the aftershocks mainly occurred in the southwestern part of the aftershock zone. The profile distribution of the earthquake sequence shows that the fault plane dips to the southeast with the dip angle of about 75°. Combined with the regional tectonic setting,focal mechanism solution and intensity distribution,we conclude that the concealed fault of the Fuyu-Zhaodong fault is the seismogenic fault of the Songyuan M_S5. 7 earthquake. This paper also relocates the earthquake sequence of the previous magnitude 5. 0 earthquake in 2017. Combined with the results of the focal mechanism solution,we believe that the two earthquakes have the same seismogenic structure,and the earthquake sequence generally develops to the southwest. The historical seismic activity since 2009 shows that after the magnitude 5. 0 earthquake in 2017,the frequency and intensity of earthquakes in the earthquake zone are obviously enhanced,and attention should be paid to the development of seismic activity in the southwest direction of the earthquake zone.展开更多
An earthquake of magnitude M5.7 occurred in Yamutu village,Songyuan City,Jilin Province,NE China(45°16′12″N/124°42′35″E)on May 28,2018,with a focal depth of 13 km.The epicenter is located at the intersec...An earthquake of magnitude M5.7 occurred in Yamutu village,Songyuan City,Jilin Province,NE China(45°16′12″N/124°42′35″E)on May 28,2018,with a focal depth of 13 km.The epicenter is located at the intersection of the Fuyu/Songyuan-Zhaodong Fault,Second Songhua River Fault and Fuyu North Fault which lies northwest of TanchengLujiang Fault(Tan-Lu Fault).The earthquake-induced widespread liquefaction structures and ground surface fissures within 3 km from the epicenter,caused serious disasters to the local surroundings.The visible liquefied structures include sand volcanoes,liquefied sand mounds,sand dikes and sand sills.Sand volcanoes can be divided into sand volcano with a crater,sand volcano without a crater and water volcano(no sand).Other soft-sediment deformation structures(SSDS)induced by the earthquake include deformation lamination,load and flame structures,deformation folds,dish structures,convolute bedding and water-escape structures.The formation process of the sand volcanoes comprises three stages:(1)building up excess pore-fluid pressure in the liquefied layer,(2)cracking of the low-permeable overlying layer,and(3)mixture of sand-water venting out of the ground surface.During the upward movement,the liquefied sand is injected into the low-permeable layer to form sand veins,sand sills and various types of deformation structures.Vertical distribution of seismic liquefaction structure can be divided into four zones:the thoroughly liquefied zone,the lower liquefied zone with SSDS,the upper liquefied zone with SSDS,and the ground surface liquefied zone.The liquefaction occurred at a burial depth of 2–5 m,and the thickness of liquefied sand is 2 m.NE-SW(35°–215°)trending compressive stress is possibly the seismogenic trigger of the Songyuan M5.7 earthquake that caused the fault(Fuyu/Songyuan-Zhaodong Fault)to reactivate.The study of the Songyuan seismic liquefaction structures gives insight into the prediction of modern earthquakes and disasterprone areas.Meanwhile it provides abundant basic material for studying earthquake-induced SSDS in both ancient and modern sediments.The research is obviously of great significance to reveal that the northern Tan-Lu Fault has entered a stage of active seismic activity since the twenty-first century.展开更多
基金sponsored by the Informatization of National Earthquake Network Rapid Report Work of China(CEA-JC/QNCZ-18325)
文摘The 2018,Songyuan,Jilin M_S5. 7 earthquake occurred at the intersection of the FuyuZhaodong fault and the Second Songhua River fault. The moment magnitude of this earthquake is M_W5. 3,the centroid depth by the waveform fitting is 12 km,and it is a strike-slip type event. In this paper,with the seismic phase data provided by the China Earthquake Network, the double-difference location method is used to relocate the earthquake sequence,finally the relocation results of 60 earthquakes are obtained. The results show that the aftershock zone is about 4. 3km long and 3. 1km wide,which is distributed in the NE direction. The depth distribution of the seismic sequence is 9km-10 km. 1-2 days after the main shock,the aftershocks were scattered throughout the aftershock zone,and the largest aftershock occurred in the northeastern part of the aftershock zone. After 3-8 days,the aftershocks mainly occurred in the southwestern part of the aftershock zone. The profile distribution of the earthquake sequence shows that the fault plane dips to the southeast with the dip angle of about 75°. Combined with the regional tectonic setting,focal mechanism solution and intensity distribution,we conclude that the concealed fault of the Fuyu-Zhaodong fault is the seismogenic fault of the Songyuan M_S5. 7 earthquake. This paper also relocates the earthquake sequence of the previous magnitude 5. 0 earthquake in 2017. Combined with the results of the focal mechanism solution,we believe that the two earthquakes have the same seismogenic structure,and the earthquake sequence generally develops to the southwest. The historical seismic activity since 2009 shows that after the magnitude 5. 0 earthquake in 2017,the frequency and intensity of earthquakes in the earthquake zone are obviously enhanced,and attention should be paid to the development of seismic activity in the southwest direction of the earthquake zone.
基金supported by the“Natural Science Foundation of Heilongjiang Province(No.JJ2016ZR0573)”“Youth Foundation of Northeast Petroleum University(No.NEPUBS201503)”+2 种基金“Northeast Petroleum University Scientific Research Start-up Fund”“Shandong Provincial Key Laboratory of Depositional Mineralization and Mineral Foundation(No.DMSMZO17009)”“Natural Science Foundation of Shandong Province(No.ZR2016DB15)”.
文摘An earthquake of magnitude M5.7 occurred in Yamutu village,Songyuan City,Jilin Province,NE China(45°16′12″N/124°42′35″E)on May 28,2018,with a focal depth of 13 km.The epicenter is located at the intersection of the Fuyu/Songyuan-Zhaodong Fault,Second Songhua River Fault and Fuyu North Fault which lies northwest of TanchengLujiang Fault(Tan-Lu Fault).The earthquake-induced widespread liquefaction structures and ground surface fissures within 3 km from the epicenter,caused serious disasters to the local surroundings.The visible liquefied structures include sand volcanoes,liquefied sand mounds,sand dikes and sand sills.Sand volcanoes can be divided into sand volcano with a crater,sand volcano without a crater and water volcano(no sand).Other soft-sediment deformation structures(SSDS)induced by the earthquake include deformation lamination,load and flame structures,deformation folds,dish structures,convolute bedding and water-escape structures.The formation process of the sand volcanoes comprises three stages:(1)building up excess pore-fluid pressure in the liquefied layer,(2)cracking of the low-permeable overlying layer,and(3)mixture of sand-water venting out of the ground surface.During the upward movement,the liquefied sand is injected into the low-permeable layer to form sand veins,sand sills and various types of deformation structures.Vertical distribution of seismic liquefaction structure can be divided into four zones:the thoroughly liquefied zone,the lower liquefied zone with SSDS,the upper liquefied zone with SSDS,and the ground surface liquefied zone.The liquefaction occurred at a burial depth of 2–5 m,and the thickness of liquefied sand is 2 m.NE-SW(35°–215°)trending compressive stress is possibly the seismogenic trigger of the Songyuan M5.7 earthquake that caused the fault(Fuyu/Songyuan-Zhaodong Fault)to reactivate.The study of the Songyuan seismic liquefaction structures gives insight into the prediction of modern earthquakes and disasterprone areas.Meanwhile it provides abundant basic material for studying earthquake-induced SSDS in both ancient and modern sediments.The research is obviously of great significance to reveal that the northern Tan-Lu Fault has entered a stage of active seismic activity since the twenty-first century.
