Ionospheric and atmospheric anomalies registered around the time of strong earthquakes in low-latitude regions are reported now regularly. Majority of these reports have the character of case studies without clear physical mechanism proposed. Here we try to present the general conception of low-latitude effects using the results of the recent author’s publications, including also rethinking the earlier results interpreted basing on recently established background physical mechanisms of anomalies generation. It should be underlined that only processes initiated by earthquake preparation are considered. Segregation of low-latitude regions for special consideration is connected with the important role of ionospheric equatorial anomaly in the seismoionospheric coupling and specific character of low-latitude earthquake initiated effects. Three main specific features can be marked in low-latitude ionospheric anomalies manifestation: the presence of magnetic conjugacy in majority of cases, local longitudinal asymmetry of effects observed in ionosphere in relation to the vertical projection of epicenter onto ionosphere, and equatorial anomaly reaction even on earthquakes outside equatorial anomaly (i.e., 30–40 LAT). The equality of effects morphology regardless they observed over land or over sea implies only one possible explanation that these anomalies are initiated by gaseous emanations from the Earth crust, and radon plays the major role. 1. Introduction Many studies for the ionospheric precursors of earthquakes have been done since 1964 when great Alaska “Good Friday” ( = 9.2) earthquake took place on the 27th of March. History of these studies is described by Pulinets and Boyarchuk [1]. We can consider the starting date of systematic studies of seismo-ionospheric coupling from publication of the book Ionospheric Precursors of the Earthquakes [2]. Pulinets [3] proposed to consider the ionospheric variations stimulated by the earthquake preparation process as one of the constituents of day-to-day ionospheric variability. This statement was questioned in some publications [4, 5]. But after revealing the main phenomenological features of ionospheric precursors [6] and their stable and confident statistical characteristics [7–10] the discussions shifted to the direction of their physical mechanism clarification. The diversity of ionospheric effects manifestation before earthquakes (positive and negative deviations from undisturbed level, local time dependence, longitudinal effect, etc.) produced confusion in heads of physicists, and instead of unitary vision
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