Dense profile probing depth extent of Pengguan Complex and Longmenshan Fault

彭关杂岩及龙门山断裂密集剖面探测深度范围

• 批准号: 391957130
• 负责人: Dr. James Mechie
• 金额: --
• 依托单位: Sektion 2.2: Geophysikalische Abbildung des Untergrunds
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/391957130?language=en
• 关键词: Dense; profile; probing; depth; extent

The main aim of this project is to investigate the deep structure beneath the Longmenshan fault zone in China, based on a very dense passive seismological profile. The Longmenshan fault zone hosted the Wenchuan earthquake of May 2008 with a magnitude (Mw) of 7.9 and the Lushan earthquake of June 2013 with a magnitude (Mw)of 6.6. Since 2008, several deep boreholes have been drilled along the fault zone about 40 km northeast of the epicentre of the Wenchuan earthquake. It is planned to mainly use the receiver-function method, to investigate the deep structure and, in particular, the structure of the Moho. Other recent experiments at the borders of Tibet have shown that the region of the lower crust, including the Moho, play an important role in the growth of the plateau.It is planned to deploy about 40-50 broadband seismic stations along the profile in spring 2018. The stations should be serviced every six months and it is planned to demobilize the stations in the autumn of 2019. The station spacing will be about 10 km at both ends of the profile. In contrast, the station density will be increased in the middle of the profile, so that the station spacing in the vicinity of the Longmenshan fault zone will be just 1-2 km. With this higher station density in the vicinity of the Longmenshan fault zone, the aim is to open the possibility of imaging structures in the crust such as the base of the Pengguan complex or the Longmenshan fault zone itself. Due to the boreholes in the region it is known that the Longmenshan fault zone is a fairly steeply dipping structure in the upper crust. Nevertheless, the group at GFZ Potsdam has succeeded in imaging with the receiver-functions method, a steeply dipping structure in the Pamir, namely the Pamir seismic zone. If we can image such structures, then we can perhaps contribute to understanding the hazards posed by the earthquake threat in the region.

该项目的主要目的是在非常密集的被动地震剖面的基础上，研究中国龙门山断裂带的深部结构。龙门山断裂带是2008年5月汶川7.9级地震和2013年6月庐山6.6级地震的发源地。自2008年以来，在汶川地震震中东北约40公里处的断裂带上钻了几个深井。计划主要使用接收函数方法，研究莫霍面的深部结构，特别是结构。最近在西藏边境进行的其他实验表明，包括莫霍面在内的下地壳区在高原的生长中发挥了重要作用。计划在2018年春季沿该剖面部署约40-50个宽带地震台站。这些车站应每六个月提供一次服务，并计划在2019年秋季解散这些车站。纵断面两端的测站间距约为10公里。相反，在剖面中部将增加台站密度，使龙门山断裂带附近的台站间距仅为1-2公里。在龙门山断裂带附近有较高的台站密度，目的是打开在地壳中成像构造的可能性，如彭关杂岩的底部或龙门山断裂带本身。根据该地区的钻孔情况，龙门山断裂带是一个上地壳倾角较大的构造。尽管如此，GFZ波茨坦的小组已经成功地用接收函数方法成像，这是帕米尔地区的一个陡峭的构造，即帕米尔地震带。如果我们能够想象这样的结构，那么我们或许可以帮助理解该地区地震威胁带来的危险。