*Jann-Yenq LIU1,2,3, Yuh-Ing Chen4, YUN-CHENG WEN2
(1.Center for Astronautical Physics and Engineering, National Central University, Taiwan, 2.Department of Space Science and Engineering, National Central University, Taiwan, 3.Center for Space and Remote Sensing Research, National Central University, Taiwan, 4.Graduate Institute of Statistics, National Central University, Taiwan)
Keywords:pre-earthquake ionospheric anomaly , total electron content, Afghanistan earthquake, global ionosphere map
The total electron content (TEC) of global ionosphere maps (GIM) is used to detect anomalies occurring during the 27-30 May 2022 moderate magnetic storm with the maximum depression of -62 nT on 28 May and the 21 June 2022 M6.0 Afghanistan earthquake with the epicenter at 33.1N, 69.5E periods. Spatial analyses show that positive anomalies frequently, 85%, appear specifically, a small area, close to the epicenter on 23-20 day (28 May-1 June) before the 2022 M6.0 Afghanistan earthquake. The large overlap period between the storm anomaly period of 27-30 May and the pre-earthquake ionospheric anomaly (PEIA) period of 28 May-1 June 2022 implies that instead of confounded effects, magnetic storm disturbances might amplify PEIAs occurrence and be helpful to find possible location of the epicenter of forthcoming large earthquakes. We further statistically examine PEIAs of the GIM TEC associated with 74 M6.0 and greater earthquakes in the Afghanistan area (20-45N ´ 55-85E) during 1999-2021. Statistical results of one sample T-test with significant level<0.05 show that the PEIA characteristics are GIM TECs significantly increase at 03:00-13:00 UT day 25-21 before the M6.0 and greater earthquakes. The agreement between the event study and the statistical result indicates that PEIAs related to the M6.0 Afghanistan earthquake have been detected.