Detection of ionospheric response to earthquakes in Mexico: case study of September 8, 2021 and September 19, 2022

Abstract

We explore the possibility of the ionospheric disturbance detection after two earthquakes (EQ) (Mw > 7) occurred on September 8, 2021, and September 19, 2022, in Mexico. The epicenter location, depth, focal mechanism, season and Space Weather background conditions were similar for the two EQs. The local time and the magnitude were different. Wave responses in the filtered slant TEC time series were revealed after both EQs at isolated satellite-receiver ray paths. The irregular variations exceeded the background fluctuation level and were not repeated on other days. Their form and temporal scales allowed us to associate them with the acoustic-gravity waves generated by the vertical displacement during the powerful EQs. The nighttime EQ on September 8, 2021, caused the medium-scale disturbances characterized with the N- and И-form fluctuations in TEC, a period of ~30 min and amplitudes of (0.1-0.2) TECU. The response to the daytime EQ on September 19, 2022, was of two types: smallscale disturbances N-, V-, И- and M-form with a 15 min period and amplitudes of (0.1-1.1) TECU; and medium-scale disturbances of N- and И-form with a period of ~30 min and amplitudes of (0.1-0.2) TECU. The presented conclusions for the Mexican region are preliminary as more statistics are needed.

Keywords

• co-seismic ionospheric disturbance
• earthquakes
• slant tec
• mexico