To further study regional deformation characteristic in the southeast margin of Ordos Block during the period between the Alanshan M5.8 and Yuncheng M4.4 earthquake swarm, we analyze continuous GPS sites around the st...To further study regional deformation characteristic in the southeast margin of Ordos Block during the period between the Alanshan M5.8 and Yuncheng M4.4 earthquake swarm, we analyze continuous GPS sites around the study area. The time-varying strain parameters removed a linear trend deviated from the background state in varying degrees since April, 2015, and began to turn back at the end of the year 2015, meanwhile, the maximum extension strain and shear strain have the bigger variation relative to others. The GPS measurement also shows that the eastward displacement rate of the stations decreases during 2015-2016 in varying degrees compared to 2011-2015, and the variation is closely related to its geologic structural location. The differential movement between the stations is converted into regional strain accumulation due to the fault locking. Further- more, during 2015-2016, the maximum extension rate oriented at near NS direction obviously increased, and the maximum contraction strain direction is changed from NW to EW direction, which contributes to strengthen extension and shear strain of the NE- striking faults, it＇s consistent with the regional background strain state of Shanxi seismic zone, this may be an important contributor to occurrence of M4.4 earthquake swarm in Yuncheng basin.展开更多
研究历史地震事件是认识地震活动规律、分析发震构造的重要途径之一。1568年5月25日(隆庆二年四月十九日申时),在西安东北高陵地区发生一次强烈地震,造成各类建筑物倒塌毁坏"尽如平地","人畜伤亡甚众"。此前的地震...研究历史地震事件是认识地震活动规律、分析发震构造的重要途径之一。1568年5月25日(隆庆二年四月十九日申时),在西安东北高陵地区发生一次强烈地震,造成各类建筑物倒塌毁坏"尽如平地","人畜伤亡甚众"。此前的地震目录将这次地震命名为陕西西安东北地震,震级为6级,极震区烈度为Ⅸ。文中通过对历史地震资料的再考证及野外调查,认为该次地震的极震区位于在泾河以北的泾阳县东南的永乐镇、高庄镇北部至高陵县及其东南姬家乡、张卜乡一带,并命名为陕西高陵地震,烈度为Ⅸ+(Ⅸ～Ⅹ)度,估算其震级可达7级。同时,对震害进行了细致分析并重绘制了该地震的等震线图,得到其极震区的位置,同时发现其等震线长轴为NWW向,与渭南-泾阳断裂相吻合。该断裂为全新世活动正断层,沿断裂地貌保留了部分断错阶地陡坎,断层剖面中可见砂土液化、张性构造裂缝等新活动遗迹,最晚活动时间为(180±30) a BP至(1 600±30) a BP之间。文中分析认为1568年陕西高陵7级地震的发震构造为渭南-泾阳断裂,该断裂与渭南塬前断裂、华山山前断裂共同构成渭河盆地东南缘的重要边界活动断裂带。展开更多
1研究背景在地震预测研究中,震中方位预测相对困难。诸多研究表明,中强地震前存在明显的地磁水平椭圆/线性极化偏振特点,且地磁水平极化长轴方向垂直于震源(地磁辐射源)方位(杨少峰等,2002;Schekitov et al,2007;Ohtaet al,2013)。据此...1研究背景在地震预测研究中,震中方位预测相对困难。诸多研究表明,中强地震前存在明显的地磁水平椭圆/线性极化偏振特点,且地磁水平极化长轴方向垂直于震源(地磁辐射源)方位(杨少峰等,2002;Schekitov et al,2007;Ohtaet al,2013)。据此认知,如果单台出现地磁水平极化异常,可给出地磁辐射源的大致走向。展开更多
基金supported by the Planned Science and Technology Project of Shanxi Province(20140313023-1)Natural Science Foundation of Shanxi(2011021024-1)
文摘To further study regional deformation characteristic in the southeast margin of Ordos Block during the period between the Alanshan M5.8 and Yuncheng M4.4 earthquake swarm, we analyze continuous GPS sites around the study area. The time-varying strain parameters removed a linear trend deviated from the background state in varying degrees since April, 2015, and began to turn back at the end of the year 2015, meanwhile, the maximum extension strain and shear strain have the bigger variation relative to others. The GPS measurement also shows that the eastward displacement rate of the stations decreases during 2015-2016 in varying degrees compared to 2011-2015, and the variation is closely related to its geologic structural location. The differential movement between the stations is converted into regional strain accumulation due to the fault locking. Further- more, during 2015-2016, the maximum extension rate oriented at near NS direction obviously increased, and the maximum contraction strain direction is changed from NW to EW direction, which contributes to strengthen extension and shear strain of the NE- striking faults, it＇s consistent with the regional background strain state of Shanxi seismic zone, this may be an important contributor to occurrence of M4.4 earthquake swarm in Yuncheng basin.
文摘研究历史地震事件是认识地震活动规律、分析发震构造的重要途径之一。1568年5月25日(隆庆二年四月十九日申时),在西安东北高陵地区发生一次强烈地震,造成各类建筑物倒塌毁坏"尽如平地","人畜伤亡甚众"。此前的地震目录将这次地震命名为陕西西安东北地震,震级为6级,极震区烈度为Ⅸ。文中通过对历史地震资料的再考证及野外调查,认为该次地震的极震区位于在泾河以北的泾阳县东南的永乐镇、高庄镇北部至高陵县及其东南姬家乡、张卜乡一带,并命名为陕西高陵地震,烈度为Ⅸ+(Ⅸ～Ⅹ)度,估算其震级可达7级。同时,对震害进行了细致分析并重绘制了该地震的等震线图,得到其极震区的位置,同时发现其等震线长轴为NWW向,与渭南-泾阳断裂相吻合。该断裂为全新世活动正断层,沿断裂地貌保留了部分断错阶地陡坎,断层剖面中可见砂土液化、张性构造裂缝等新活动遗迹,最晚活动时间为(180±30) a BP至(1 600±30) a BP之间。文中分析认为1568年陕西高陵7级地震的发震构造为渭南-泾阳断裂,该断裂与渭南塬前断裂、华山山前断裂共同构成渭河盆地东南缘的重要边界活动断裂带。
文摘1研究背景在地震预测研究中,震中方位预测相对困难。诸多研究表明,中强地震前存在明显的地磁水平椭圆/线性极化偏振特点,且地磁水平极化长轴方向垂直于震源(地磁辐射源)方位(杨少峰等,2002;Schekitov et al,2007;Ohtaet al,2013)。据此认知,如果单台出现地磁水平极化异常,可给出地磁辐射源的大致走向。
