The variations of plasma density recorded by CSES-1 satellite possibly related to Mexico Ms 7.1 earthquake on 8th September 2021

This work analyzed the Ms 7.1 earthquake occurred at 01:47 UT on September 8th, 2021, in Acapulco City, Guerrero, Mexico (17.12° N, 99.6° W, N and W represent north and west, respectively) with a 30 ​km focal depth by using multiple parameters recorded by China Seismo-Electromagnetic Satellite-1 (CSES-1). In this work, we studied the electron density (Ne) recorded by langmuir probe and O+ from plasma analyzer package at a height of 507 ​km 15 days before the earthquake. After excluding the plasma density variations caused by the geomagnetic storms on August 28th and September 7th, the results revealed that the nighttime Ne, and O+ increased on September 2nd (6 days before the earthquake) simultaneously within ±10° in latitude and ±10° in longitude around the epicenter. In addition, the enhancement was also found in electron density profile (EDP) between 200 ​km and 300 ​km derived from GNSS radio occultation data. Not only the different particle species (Ne and O+) at 507 ​km, but also electron density at 507 ​km and EDP in lower ionosphere shown anomalies 6 days before the earthquake. Basing on the results, we suggest that the enhancements of Ne, O+, and EDP on September 2nd are possible related to the Mexico Ms 7.1 earthquake on September 8th.