中国南极长城站地区地震活动特征及其周边深部结构

China Antarctic Great Wall Station area and its surrounding is located on the northern part of the tectonically-complicated Antarctic Peninsula, which is affected by the action of the Antarctic plate, the Scotia plate and the South American plate. There are three types of plate boundaries (i.e. divergent boundary, convergent boundary and transform boundary) in the study area. Thus the study area is an ideal site to study on seismology. However, due to ultra-climate conditions, seismological observation and relevant seismological research in Antarctica is still preliminary. The objective of this project is to carry out the relevant seismological research by using the high-quality broadband seismic data collected from the Antarctic Great Wall Station Seismic Station (CCZ). We shall use the single-station event location method to locate local earthquakes occurred in the Great Wall Station area. The located results are used to analyze the seismic activity characteristics in the Bransfield Strait, the South Shetland Islands and the South Shetland Trench, and to give the evidence that whether the subduction beneath the South Shetland Trench is ceased or on-going. Meanwhile, we shall try to carry out the icequake analysis. In addition, we shall also collect the seismic data from three broadband stations of Global Seismograph Network in the study area. Based on the results of receiver function and surface wave imaging, and combined with upper mantle anisotropy and other geophysical and geological data, we shall analyze the crust and upper mantle structure characteristics in the Great Wall Station area and its surrounding and discuss the geodynamic implication of different plates collision.

中国南极长城站地区及周边位于南极半岛北部，受到南极板块、斯科舌板块和南美板块的影响，构造复杂，存在着多种类型的板块边界（发散边界、会聚边界和转换边界），是开展地震学研究的理想场所。由于南极极端的气候条件，限制了地震观测的开展，对这一地区的地震活动特征和深部结构的了解仍然是初步的。本项目旨在通过南极长城站地震台（CCZ）的地震观测，收集高质量地震观测资料，开展相关研究。对发生在长城站地区的近震进行单台定位测量，分析布兰斯菲尔德海峡、南设得兰群岛和南设得兰海沟的地震活动特征，提供南设得兰海沟下俯冲作用是否停止的证据，同时尝试开展冰震分析。此外，我们还将利用CCZ台及其周边全球台网的3个地震台的资料，在对宽频带资料的接收函数、面波方法分析的基础上，结合上地幔各向异性以及其它地球物理和地质资料，分析长城站地区及周边地壳上地幔结构特征，并讨论该区域不同板块碰撞形变的动力学含义。

中国南极长城站地区位于构造复杂的南极半岛北部，这里受到南极板块、南美板块和斯科舍板块的强烈影响，是开展地震学研究的理想场所。本项目依托南极科学考察平台开展了南极长城站地区地震观测和研究。项目组成员参加并顺利完成了中国第29、31和33次南极科学考察，对南极长城站地震台进行了常规维护并构建了数据传输系统，获得了长城站地震台自2011年至2016年的连续观测的高质量地震数据，并且还收集了长城站周边的3个全球台网台站（PMSA台、HOPE台和EFI台）自2001年以来的地震事件波形资料。利用长城站地震台站观测资料，开展了单台定位分析结果，给出了菲尼克斯板块的俯冲作用仍然进行着的地震学证据，并且发现距长城站东南约40 km处地震非常密集的区域，对应了Orca的海底火山。在接收函数和面波分析的基础上给出了长城站地区地壳（地壳厚度为21—30 km）和上地幔速度结构（岩石圈厚度约为70 km），通过远震横波分裂测量，显示快波方向平行于海沟的特征，反映了软流圈地幔流是该区域上地幔各向异性的主要成因。此外，菲尔德斯半岛浅层勘探实验结果显示了典型的火山岛构造特征。