Geothermal Anomalies and Coupling with the Ionosphere before the 2020 Jiashi Ms6.4 Earthquake

Rock temperature reflects the adjustment in crustal stress, and fluctuation of ionospheric electron concentration is closely related to short-term disturbances stress field. Their coupling may reveal effects before strong earthquakes. This study explores rock changes mechanical-electrical lithosphere–ionosphere Jiashi Ms6.4 earthquake on 19 January 2020. The observed data were detrended by general polynomial piecewise fitting; three observation points within 150 km epicenter found show significant fluctuations 15 days earthquake. peak occurred synchronously five earthquake, variation range was approximately 10−3 orders magnitude. Five electromagnetic satellite Zhangheng-1 an anomalous orbit near epicenter, with a maximum value 2.01 × 1010 m−3. loading/unloading response ratio (LURR) calculated using small earthquakes 100 epicenter; it showed that large ionosphere at high LURR, indicating high-stress accumulation region. Various anomalies appeared simultaneously indicate fault rupture, which be caused acoustic-gravity wave, synchronous between lithosphere atmosphere ionosphere.