Multi‐Instrument Investigation of the Pre‐Seismic Ionospheric Response to 2021 Haiti Earthquake

Abstract The study of pre‐seismic variations in the ionosphere due to 2021 Haiti earthquake (Mw = 7.2) is carried out using ground and space‐based instruments. The day time ionospheric response is analyzed using Vertical Total Electron Content (VTEC) from IGS stations and electron density from Swarm satellite data. Results demonstrate that bandpass filtered VTEC reveals clear, pronounced, pre ‐ seismic oscillations of peak magnitudes of ∼0.2 TECU on 05 August 2021, that is, 9 days before the earthquake for stations near and just outside the earthquake preparation zone. Similarly, enhanced wave‐like oscillations are also evident in the filtered VTEC data near the conjugate stations on the same day. Another unique feature during 05 August 2021 is the anomalous enhancement of northern Equatorial Ionization Anomaly crest shown by Swarm electron density data. Such an enhancement is not observed for other days during August. This is also concurrent with the drop in Relative humidity occurred during the same day near the impending epicenter region. Hence the concomitant anomalies found in various atmospheric and ionospheric parameters suggest that the anomalies found on 05 August 2021 is plausibly related to the Haiti 2021 earthquake. This study also sheds some light into similarities with the Haiti 2010 event which occurred very close to the epicenter of 2021 event, hence emphasizing the need of detailed study of the Earthquake prone regions of Haiti using multiple precursor parameters.