摘要
为分析2021年7月29日阿拉斯加8.2级地震引起的电离层响应,利用地震附近的全球导航卫星系统(Global Navigation Satellite System,GNSS)观测数据估算电离层总电子含量(Ionospheric Total Electron Content,TEC)及同震电离层扰动(Coseismic Ionospheric Disturbances,CIDs).从多角度对CIDs的时空分布特征进行分析,并与阿拉斯加2018年7.9级走滑型地震以及2020年7.8级逆断层地震引起的CIDs对比.在地震西南方向探测到两类CIDs,最大扰动振幅约0.8 TECU(1 TECU=1016 el/m^(2)),并且在西南方向距离震中约1094 km的测高站EA653探测到CIDs.在震中西北、东北和北方向探测到传播速度相近的CIDs.根据CIDs的速度和频率大小将CIDs分为两类,第一类CIDs的传播速度为1.87 km·s^(-1),频率约为3.8 mHz,可能由地震声波引起,扰动量级最大;第二类CIDs的传播速度为0.85~1.09 km·s^(-1),中心频率约在3.0 mHz或者5.7 mHz附近,为地震声波引起的另一类电离层扰动.逆断层地震引起的CIDs比走滑型地震更加显著,表明地震引起的垂直地表运动在CIDs的形成中起主要作用.三次地震在西南方向均引起显著的CIDs,与地震破裂方向较为一致,该地区大地震引起的CIDs可能具有较为明显的方向性,具体形成机制有待于进一步研究.
The ionospheric response caused by the Alaska 8.2 earthquake on July 29,2021 is studied based on the Global Navigation Satellite System(GNSS)observation data near the earthquake.The calculation method of Ionospheric Total Electron Content(TEC)and its perturbation is constructed.Coseismic Ionospheric Disturbances(CIDs)are analyzed from multiple perspectives,and compared with CIDs caused by Alaska's 7.9-magnitude strike-slip earthquake in 2018 and the 7.8-magnitude reverse fault earthquake in 2020.Two types of CIDs were detected in the southwest direction of the earthquake,and the maximum disturbance amplitude was about 0.8 TECU(1 TECU=1016 el/m^(2)).Similar ionospheric disturbances are detected by the ionosonde station EA653,which is about 1094 km away from the epicenter in the southwest of the earthquake.CIDs with similar propagation speeds were detected in the northwest,northeast and north directions of the earthquake.According to the velocity and frequency of CIDs,CIDs are divided into two categories.The propagation velocity and frequency of the first type of CIDs is 1.87 km·s^(-1)and 3.8 mHz,respectively.This type of CIDs may be caused by sound waves generated by earthquakes,and the magnitude of disturbance is the largest.The propagation speed of the second CIDs is 0.85~1.09 km·s^(-1),and its frequency is about 3.0 mHz or 5.7 mHz.The second type of CIDs may be another type of ionospheric disturbance caused by sound waves.The CIDs caused by reverse fault earthquakes are more significant than those caused by strike-slip earthquakes,indicating that the vertical surface motion caused by earthquakes plays a major role in the formation of CIDs.The three earthquakes have caused significant CIDs in the southwest direction of the earthquake.The propagation direction of CIDs is consistent with the direction of earthquake rupture.The CIDs caused by large earthquakes in this area may have obvious directivity.The specific formation mechanism needs to be further studied.
作者
罗亦泳
吴大卫
张立亭
LUO YiYong;WU DaWei;ZHANG LiTing(Faculty of Geomatics,East China University of Technology,Nanchang 330013,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第2期461-476,共16页
Chinese Journal of Geophysics
基金
国家自然科学基金(41861058)资助。
关键词
同震电离层扰动
电离层总电子含量
全球导航卫星系统
阿拉斯加地震
Coseismic ionospheric disturbances
Total ionospheric electron content
Global navigation satellite system
Earthquake in Alaska
