On October 27, 2001, a large earthquake with M S6.0, named the Yongsheng earthquake, occurred along the Jinshajiang segment of Chenghai fault in Yongsheng County, Yunnan Province. It is the largest event to occur alon...On October 27, 2001, a large earthquake with M S6.0, named the Yongsheng earthquake, occurred along the Jinshajiang segment of Chenghai fault in Yongsheng County, Yunnan Province. It is the largest event to occur along the Chenghai fault in the last 200 years. The seismo-geological survey shows that the seismogenic fault, which is the Jinshajiang segment of Chenghai fault, takes left-lateral strike-slip as its dominant movement pattern. According to differences in vertical motion, motion time, landforms and scales, the Chenhai fault can be divided into eight segments. The Jinshajiang segment has a vertical dislocation rate of 0.4 mm/a, far lower than the mean rate of the Chenghai fault, about 2.0 mm/a. It’s deduced that the two sides of Jinshajiang segment “stuck" tightly and hindered the strike-slip of the Chenghai fault. The strong earthquake distribution before this event shows that the Jinshajiang segment was in the seismic gap. The Chenghai fault, as a boundary of tectonic sub-blocks, makes the Northwest Yunnan block and the Middle Yunnan block move clockwise, and their margins move oppositely along the Chenghai fault. In the motion process of the Chenghai fault, structural hindrance and the seismic gap of strong earthquakes are propitious to the concentration and accumulation of structure stress. As a result, the Yongsheng M S6.0 earthquake occurred. The Sujiazhuang-Shangangfu segment is similar to the Jinshajiang segment with a low vertical motion rate of 0.3 mm/a and in the seismic gap. So it’s postulated that the segment may become a new structure hindrance, and the Yongsheng M S6.0 earthquake may trigger the occurrence of future large earthquakes along this segment.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
文摘On October 27, 2001, a large earthquake with M S6.0, named the Yongsheng earthquake, occurred along the Jinshajiang segment of Chenghai fault in Yongsheng County, Yunnan Province. It is the largest event to occur along the Chenghai fault in the last 200 years. The seismo-geological survey shows that the seismogenic fault, which is the Jinshajiang segment of Chenghai fault, takes left-lateral strike-slip as its dominant movement pattern. According to differences in vertical motion, motion time, landforms and scales, the Chenhai fault can be divided into eight segments. The Jinshajiang segment has a vertical dislocation rate of 0.4 mm/a, far lower than the mean rate of the Chenghai fault, about 2.0 mm/a. It’s deduced that the two sides of Jinshajiang segment “stuck" tightly and hindered the strike-slip of the Chenghai fault. The strong earthquake distribution before this event shows that the Jinshajiang segment was in the seismic gap. The Chenghai fault, as a boundary of tectonic sub-blocks, makes the Northwest Yunnan block and the Middle Yunnan block move clockwise, and their margins move oppositely along the Chenghai fault. In the motion process of the Chenghai fault, structural hindrance and the seismic gap of strong earthquakes are propitious to the concentration and accumulation of structure stress. As a result, the Yongsheng M S6.0 earthquake occurred. The Sujiazhuang-Shangangfu segment is similar to the Jinshajiang segment with a low vertical motion rate of 0.3 mm/a and in the seismic gap. So it’s postulated that the segment may become a new structure hindrance, and the Yongsheng M S6.0 earthquake may trigger the occurrence of future large earthquakes along this segment.
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)。
