Electromagnetic anomalies detection over seismic regions during an earthquake
Authors: Recchiuti Dario , D'angelo Giulia , Papini Emanuele , Diego Piero , Cicone Antonio , Parmentier Alexandra , Ubertini Pietro , Battiston Roberto , Piersanti Mirko 
Published: March 2022

&lt;p&gt;&lt;span&gt;The definition of the statistical distribution of the ionospheric electromagnetic (EM) waves energy &lt;/span&gt;&lt;span&gt;in absence of seismic activity and other anomalous inputs (such as the ones derived by solar &lt;/span&gt;&lt;span&gt;forcing) is a necessary step in order to determine a background in the ionospheric EM emissions &lt;/span&gt;&lt;span&gt;over seismic regions. An EM signal which differs from the background (exceeding a statistically &lt;/span&gt;&lt;span&gt;meaningful threshold) should be considered as a potential event to be investigated. &lt;/span&gt;&lt;span&gt;In this work, by means of the FIF (Fast Iterative Filtering) data analysis technique, we performed &lt;/span&gt;&lt;span&gt;a&lt;/span&gt; &lt;span&gt;multiscale&lt;/span&gt; &lt;span&gt;analysis&lt;/span&gt; &lt;span&gt;of&lt;/span&gt; &lt;span&gt;the&lt;/span&gt; &lt;span&gt;ionospheric&lt;/span&gt; &lt;span&gt;environmental&lt;/span&gt; &lt;span&gt;background,&lt;/span&gt; &lt;span&gt;using&lt;/span&gt; &lt;span&gt;almost&lt;/span&gt; &lt;span&gt;the&lt;/span&gt; &lt;span&gt;entire &lt;/span&gt;&lt;span&gt;CSES01 (China Seismo-ElectroMagnetic Satellite) electric and magnetic field dataset (2019 - &lt;/span&gt;&lt;span&gt;2021), by creating the map of the averaged relative energy (&lt;/span&gt;&lt;span&gt;&amp;#949;&lt;/span&gt;&lt;sub&gt;&lt;span&gt;rel&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;) over a 3&amp;#176; x 3&amp;#176; latitude-longitude &lt;/span&gt;&lt;span&gt;cell, depending on both spatial and temporal scale of the ionospheric medium.&lt;/span&gt;&lt;br&gt;&lt;span&gt;In&lt;/span&gt; &lt;span&gt;order&lt;/span&gt; &lt;span&gt;to&lt;/span&gt; &lt;span&gt;make&lt;/span&gt; &lt;span&gt;a&lt;/span&gt; &lt;span&gt;robust&lt;/span&gt; &lt;span&gt;discrimination&lt;/span&gt; &lt;span&gt;between&lt;/span&gt; &lt;span&gt;external&lt;/span&gt; &lt;span&gt;(atmospheric,&lt;/span&gt; &lt;span&gt;ionospheric, &lt;/span&gt;&lt;span&gt;magnetospheric,&lt;/span&gt; &lt;span&gt;solar&lt;/span&gt; &lt;span&gt;activities)&lt;/span&gt; &lt;span&gt;and&lt;/span&gt; &lt;span&gt;internal&lt;/span&gt; &lt;span&gt;(earthquakes,&lt;/span&gt; &lt;span&gt;volcanoes)&lt;/span&gt; &lt;span&gt;sources&lt;/span&gt; &lt;span&gt;generating &lt;/span&gt;&lt;span&gt;anomalous signals, we took into account geomagnetic activity conditions in terms of the Sym-H &lt;/span&gt;&lt;span&gt;index.&lt;/span&gt;&lt;br&gt;&lt;span&gt;Here we present the results obtained for the August 14, 2021 Haitian earthquake (&lt;/span&gt;&lt;span&gt;7&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;span&gt;2&lt;/span&gt; &lt;span&gt;M&lt;/span&gt;&lt;sub&gt;&lt;span&gt;W&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;) and &lt;/span&gt;&lt;span&gt;the September 27, 2021 Crete (Greece) earthquake (&lt;/span&gt;&lt;span&gt;6&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;span&gt;0&lt;/span&gt; &lt;span&gt;M&lt;/span&gt;&lt;span&gt;&lt;sub&gt;W&lt;/sub&gt;).&lt;/span&gt;&amp;#160;&lt;/p&gt;