Dense profile probing depth extent of Pengguan Complex and Longmenshan Fault

该项目的主要目的是根据一个非常密集的被动地震剖面来研究中国龙门山断裂带之下的深部结构。龙门山断裂带承载了2008年5月的汶川地震，震级（Mw）为7.9级，2013年6月的芦山地震，震级（Mw）为6.6级。自2008年以来，沿着汶川地震震中东北约40公里的断裂带，沿着钻了几个深钻孔。计划主要使用接收函数方法，调查深部结构，特别是莫霍面的结构。最近在西藏边界的其他实验表明，下地壳的区域，包括莫霍面，在高原的生长中起着重要作用。计划在2018年春季沿剖面部署约40-50个宽带地震台站沿着。这些车站应每六个月维修一次，计划于2019年秋季拆除车站。剖面两端的测站间距约为10 km。相反，在剖面中部将增加测站密度，使龙门山断裂带附近的测站间距仅为1-2 km。在龙门山断裂带附近有这样高的测站密度，其目的是打开对地壳中的构造成像的可能性，例如彭官杂岩的基底或龙门山断裂带本身。由于该地区的钻孔，人们知道龙门山断裂带是上地壳中一个相当陡倾的构造。然而，GFZ波茨坦的小组成功地用接收函数法对帕米尔的一个陡倾构造，即帕米尔地震带进行了成像。如果我们能够对这些结构进行成像，那么我们也许可以帮助了解该地区地震威胁所造成的危害。

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.