Possible ionospheric anomalies associated with the 2009 Mw 6.4 Taiwan earthquake from DEMETER and GNSS TEC

Abstract

The recent advances in satellite based ionosphere monitoring provided more evidence about earthquake (EQ) precursors from lithosphere ionosphere coupling mechanism. In this paper, we investigate ionospheric anomalies associated with the December 19, 2009, Taiwan EQ (Mw = 6.4), that occurred on UT = 13:02 h. Seismo ionospheric anomalies are evaluated during 31 days (20 day before followed by 10 days after the EQ) in the data of French Satellite Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and validated from Global Navigation Satellite System (GNSS) retrieved Total Electron Content (TEC). The day time values of ISL (Langmuir Probe) and IAP (Ion Analyzer) from DEMETER point to significant ionospheric perturbations within 5 days associated with EQ day. Moreover, GNSS stations of International GNSS Service (IGS) within EQ preparation zone also validate anomalies in ionosphere prior/after the Mw 6.4, Taiwan EQ. Moreover, spatial and temporal analyses of daily ionospheric indices from DEMETER and GNSS point to simultaneous enhancement in electron density, ion density, electron temperature and TEC related to the main shock during quiet geomagnetic storm (Dst < − 30 nT, Kp ≤ 3). All these evidence aids in promoting the lithosphere- ionosphere coupling over the epicenter of Mw 6.4 during the preparation period from DEMETER and GNSS TEC.