  In this study, with cross-valid analysis of total electron content (TEC) data
of the global ionospheric map (GIM) from GPS and plasma parameters data
recorded by China Seismo-Electromagnetic Satellite (CSES), signatures of
seismic-ionospheric perturbations related to the 14 July 2019 Mw7.2 Laiwui
earthquake were detected. After distinguishing the solar and geomagnetic
activities, three positive temporal anomalies were found around the epicenter 1
day, 3 days and 8 days before the earthquake (14 July 2019) along with a
negative anomaly 6 days after the earthquake, which also agrees well with the
TEC spatial variations in latitude-longitude-time (LLT) maps. To further
confirm the anomalies, the ionospheric plasma parameters (electron, O+and
He+densities) recorded by the Langmuir probe (LAP) and Plasma Analyzer Package
(PAP) onboard CSES were analyzed by using the moving mean method (MMM), which
also presented remarkable enhancements along the orbits around the epicenter on
day 2, day 4 and day 7 before the earthquake. To make the investigations more
convincing, the disturbed orbits were compared with their corresponding four
nearest revisiting orbits, whose results indeed indicate the existence of
plasma parameters anomalies associated with the Laiwui earthquake. All these
results illustrated that the GPS and CSES observed unusual ionospheric
perturbations are highly associated with the Mw 7.2 Laiwui earthquake, which
also strongly indicates the existence of pre-seismic ionospheric anomalies over
the earthquake region
