2019年南极长城站地区地震活动特征  

Seismicity of the Antarctica Great Wall Station Area in 2019

作　　者：郭钊玥 常利军[1] GUO ZhaoYue;CHANG LiJun(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]中国地震局地球物理研究所,北京100081

出　　处：《地球物理学报》2024年第10期3814-3827,共14页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(42074053,41930218)资助。

摘　　要：基于中国第35次南极科学考察期间完成改建的长城站地震台2019年记录的宽频带三分量连续波形数据,本文发展了一种交错网格搜索的单台定位方法并将其应用于长城站地区的地震定位研究,定位了35个信噪比较高的近震,获得了2019年南设得兰群岛及周边地区的地震分布图.结果显示,地震主要沿NE走向的南设得兰群岛分布,最大震级为M_(L)4.4,最小震级为M_(L)1.6,震源深度范围为12~115 km.通过该区域地震活动特征的分析可知,相对于稳定的南极大陆内部,长城站所在的南设得兰群岛及周边地区地震活动性较强,主要是由于该区域受到南极板块、南美板块和斯科舍板块直接或间接的作用所致.南设得兰群岛南部及其西侧靠近南设得兰海沟的弧前盆地分布着一些中源深度的地震,说明该区域受到板块俯冲作用的影响,这直接给出了菲尼克斯板块向南设得兰群岛下的俯冲作用仍然进行的地震学证据.布兰斯菲尔德海峡位于南设得兰群岛岛弧的弧后盆地,该区域仍然沿NWSE方向扩张,存在显著的火山活动和岩浆热液的运动,推测该区域发生的地震与火山活动有关.This paper developed a single station location method with interleaved grid search, based on the broadband three-component continuous waveform data recorded in 2019 at the Antarctic Great Wall Seismic Station, which completed its reconstruction during the 35th Antarctic Scientific Expedition of China. The single station location method was conducted and applied to seismic location studies in the Great Wall Station area, resulting in the location of 35 local seismic events with high signal-to-noise ratios and the generation of distribution map of events in 2019 in the South Shetland Islands region. The results show that the events are predominantly distributed along the NE-trending South Shetland Islands. The maximum magnitude is M_(L)4.4, while the minimum magnitude is M_(L)1.6, with the focal depth range of 12~115 km. The analysis of the seismicity in the region reveals that the seismicity in the South Shetland Islands, where the Great Wall Station is located, is stronger than that in the stable Antarctic continent. This is mainly due to the region’s direct or indirect influence from the Antarctic Plate, the South American Plate and the Scotia Plate. Some intermediate-depth earthquakes are distributed in the southern part of the South Shetland Islands and the fore-arc basin near the South Shetland Trench on its west side, indicating that the region is affected by plate subduction. This directly gives the seismological evidence that the subduction of the Phoenix Plate beneath the South Shetland Islands is still ongoing. The Bransfield Strait is situated within the back-arc basin of the South Shetland Islands Arc. The region continues to expand in NW-SE direction, exhibiting notable volcanic activity and magmatic hydrothermal movement. It is postulated that the seismicity in the region is associated with volcanic activity.

关 键 词：长城站地震台 地震定位 地震活动 板块俯冲 火山活动 

分 类 号：P315[天文地球—地震学]