Based on the seismic data recorded by the China Earthquake Networks Center(CENC) in the Luxian area from January 2009 to October 2021,the 3D V_P,V_S, V_P/V_S structures and seismic locations of the area are obtained b...Based on the seismic data recorded by the China Earthquake Networks Center(CENC) in the Luxian area from January 2009 to October 2021,the 3D V_P,V_S, V_P/V_S structures and seismic locations of the area are obtained by joint inversion using the V_P/V_S model consistency-constrained double-difference tomography method(tomoDDMC).The earthquakes in the study area are mainly concentrated at a depth of 2-6 km,and the focal depth is generally shallow.The Ms 6.0 Luxian earthquake occurred at the transition zone of high-and low-velocity anomalies and the aftershock sequence was distributed along the edge of the low-V_P zone.A small number of foreshocks occurred on the west side of the M_S 6.0 Luxian earthquake,while most of the aftershocks were distributed on the east side of the M_S 6.0 Luxian earthquake.The aftershock sequence consisted of three seismic bands with different trends,and the overall distribution was in a NWW direction,which was inconsistent with the spatial distribution of the main active faults nearby.In addition,the spatiotemporal distribution of earthquakes and the variation of b-values are closely related to the industrial water injection activities in the study area,reflecting the activation of pre-existing hidden faults under certain tectonic and stress environments leading to seismic activities in the area.展开更多
An M=6.0 earthquake occurred on February 23, 2001 in the western Sichuan Province, China. The macro seismic epicenter situated in the high mountain-narrow valley region between Yajiang and Kangding counties. According...An M=6.0 earthquake occurred on February 23, 2001 in the western Sichuan Province, China. The macro seismic epicenter situated in the high mountain-narrow valley region between Yajiang and Kangding counties. According to field investigation in the region, the intensity of epicentral area reached VIII and the areas with intensity VIII, VII and VI are 180 km2, 1 472 km2 and 3 998 km2, respectively. The isoseismals are generally in elliptic shape with major axis trending near N-S direction. The earthquake destroyed many buildings and produced some phenomena of ground failure and mountainous disasters in the area with intensity VIII. This event may be resulted from long-term activities of the Litang fault and Yunongxi fault, two main faults in the western Sichuan. The movements between the main faults made the crust stress adjusted and concentrated, and finally the earthquake on a secondary fault in the block released a quite large energy.展开更多
1研究背景。Hayakawa在1996年提出的地磁垂直强度极化方法在我国广泛应用。该方法通过数值模拟获知一次源来自高空电离层的极化值小于1,源自于震源的极化值大于或约等于1(Hayakawa et al,1996),Hayakawa利用该方法对1993年的关岛8级地...1研究背景。Hayakawa在1996年提出的地磁垂直强度极化方法在我国广泛应用。该方法通过数值模拟获知一次源来自高空电离层的极化值小于1,源自于震源的极化值大于或约等于1(Hayakawa et al,1996),Hayakawa利用该方法对1993年的关岛8级地震进行研究,发现震前垂直强度极化Yz h值逐渐增大直到发震时达最大值,震后恢复。近年我国学者研究发现地震往往发生在台站出现极化值高值异常后的1个月时间内(冯志生等,2010),发震地点在异常空间等值线的阈值线附近(冯丽丽等,2021),这种极化值异常与外空场活动无关(何畅等,2017)。展开更多
基金supported by the Fundamental Research Funds for the Institute of Earthquake Forecasting, China Earthquake Administration(CEAIEF20220211 and CEAIEF20220401)。
文摘Based on the seismic data recorded by the China Earthquake Networks Center(CENC) in the Luxian area from January 2009 to October 2021,the 3D V_P,V_S, V_P/V_S structures and seismic locations of the area are obtained by joint inversion using the V_P/V_S model consistency-constrained double-difference tomography method(tomoDDMC).The earthquakes in the study area are mainly concentrated at a depth of 2-6 km,and the focal depth is generally shallow.The Ms 6.0 Luxian earthquake occurred at the transition zone of high-and low-velocity anomalies and the aftershock sequence was distributed along the edge of the low-V_P zone.A small number of foreshocks occurred on the west side of the M_S 6.0 Luxian earthquake,while most of the aftershocks were distributed on the east side of the M_S 6.0 Luxian earthquake.The aftershock sequence consisted of three seismic bands with different trends,and the overall distribution was in a NWW direction,which was inconsistent with the spatial distribution of the main active faults nearby.In addition,the spatiotemporal distribution of earthquakes and the variation of b-values are closely related to the industrial water injection activities in the study area,reflecting the activation of pre-existing hidden faults under certain tectonic and stress environments leading to seismic activities in the area.
文摘An M=6.0 earthquake occurred on February 23, 2001 in the western Sichuan Province, China. The macro seismic epicenter situated in the high mountain-narrow valley region between Yajiang and Kangding counties. According to field investigation in the region, the intensity of epicentral area reached VIII and the areas with intensity VIII, VII and VI are 180 km2, 1 472 km2 and 3 998 km2, respectively. The isoseismals are generally in elliptic shape with major axis trending near N-S direction. The earthquake destroyed many buildings and produced some phenomena of ground failure and mountainous disasters in the area with intensity VIII. This event may be resulted from long-term activities of the Litang fault and Yunongxi fault, two main faults in the western Sichuan. The movements between the main faults made the crust stress adjusted and concentrated, and finally the earthquake on a secondary fault in the block released a quite large energy.
文摘1研究背景。Hayakawa在1996年提出的地磁垂直强度极化方法在我国广泛应用。该方法通过数值模拟获知一次源来自高空电离层的极化值小于1,源自于震源的极化值大于或约等于1(Hayakawa et al,1996),Hayakawa利用该方法对1993年的关岛8级地震进行研究,发现震前垂直强度极化Yz h值逐渐增大直到发震时达最大值,震后恢复。近年我国学者研究发现地震往往发生在台站出现极化值高值异常后的1个月时间内(冯志生等,2010),发震地点在异常空间等值线的阈值线附近(冯丽丽等,2021),这种极化值异常与外空场活动无关(何畅等,2017)。
