South Atlantic Anomaly, Ionospheric Signals from Seismic Events

Abstract

The purpose of this paper is to analyze the most significant events that occurred in the period 1996-2018 located under the South Atlantic Anomaly (SAA), where the earth's magnetic field is weaker and the trapped particles during the geomagnetic storms suffer decay over time. The time examined corresponds to the Solar Cycles 23 and 24; the area covered is defined by the following coordinates: 0N, −50S, 40E, −90W. Some significant events in this region reported Very Low Frequency (VLF) and Ultra Low Frequency (ULF) waves before the event, varying from minutes, hours, and even weeks before the earthquakes. Our study searches for a mechanism to explain why the crust creates electromagnetic signs detected at the ionosphere. Piezoelectric currents flow on the crust, combining with the magnetic field lines, temporarily producing pre-seismic electromagnetic pulses that are detected at the ionosphere prior to the events. The mechanism that allows electromagnetic signs to be detected at the ionosphere is also elucidated. These signs are brief, and they will cease with the beginning of the shock or shortly thereafter. However, some features contribute to making the signs impossible to detect, involving crust materials, location, magnitude, and depths. We suggest that these ionospheric events could happen for other kinds of hazard events, such as Volcanos.