Effectiveness of the Relative -Barbier Parameter
 in the Search for Ionospheric Precursors of Earthquakes

A study of temporal variations of the complex relative δ-Barbier parameter (δBarbier) was carried outto evaluate its effectiveness in the search for seismo-ionospheric precursors. For this purpose, its behavior(according to 15-min measurements of ionospheric parameters) was considered before two strong earthquakesfor which seismo-ionospheric precursors had already been detected. The first earthquake (with magnitudeM = 6.3) occurred on April 6, 2009 (L’Aquila, Italy) at an epicentral distance of ~93 km from the Romeground-based vertical ionospheric sounding station, and the second earthquake (with magnitude M = 7.2)occurred on January 30, 2016, while its epicenter was ~117 km from the ground-based vertical ionosphericsounding station located on the territory of the Paratunka Kamchatka complex geophysical observatory. Inboth cases, specific features were identified in the behavior of the δBarbier parameter that coincided in timewith the previously detected ionospheric precursors of these earthquakes. This allows us to conclude that theeffectiveness of using the δBarbier parameter in the search for seismo-ionospheric precursors has been successfullyverified