The VARION approach to volcanoes: case study on 2021 Etna eruptions
Authors: Ravanelli Michela , Ferrara Federico , Fuso Federica , Cannata Andrea , Crespi Mattia , Occhipinti Giovanni 
Published: March 2022

&lt;p&gt;&lt;span&gt;&lt;span&gt;The 2022 Tonga event&lt;/span&gt; &lt;span&gt;highlight the necessity to have&lt;/span&gt; &lt;span&gt;more and more&lt;/span&gt; &lt;span&gt;kn&lt;/span&gt;&lt;span&gt;owledge about the&lt;/span&gt; &lt;span&gt;activity&lt;/span&gt;&lt;br&gt;&lt;span&gt;of&lt;/span&gt; &lt;span&gt;volcanoes.&lt;/span&gt; &lt;span&gt;To this point&lt;/span&gt;&lt;span&gt;, it is well known that volcanoes explosion can&lt;/span&gt; &lt;span&gt;t&lt;/span&gt;&lt;span&gt;rigger ionospheric&lt;/span&gt;&lt;br&gt;&lt;span&gt;perturbation detectable through the&lt;/span&gt; &lt;span&gt;Global Navigation Satellite S&lt;/span&gt;&lt;span&gt;ystem (&lt;/span&gt;&lt;span&gt;GNSS&lt;/span&gt;&lt;span&gt;)&lt;/span&gt; &lt;span&gt;signal&lt;/span&gt; &lt;span&gt;[&lt;/span&gt;&lt;span&gt;1&lt;/span&gt;&lt;span&gt;]&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;/span&gt;&lt;span&gt;&lt;/span&gt;&lt;span&gt;&lt;/span&gt;&lt;span&gt;&lt;br&gt;&lt;span&gt;T&lt;/span&gt;&lt;span&gt;he VARION (Variometric Approach for Real&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span&gt;Time Ionosphere Observation) algorithm has been&lt;/span&gt;&lt;br&gt;&lt;span&gt;successfully applied to&lt;/span&gt; &lt;span&gt;detection&lt;/span&gt; &lt;span&gt;of ionospheric perturbations&lt;/span&gt; &lt;span&gt;in several real&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span&gt;time scenarios [&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;, 3&lt;/span&gt;&lt;span&gt;].&lt;/span&gt;&lt;br&gt;&lt;span&gt;VARION, thus, estimates sTEC (slant total electron&lt;/span&gt; &lt;span&gt;content) variations starting from the single time&lt;/span&gt;&lt;br&gt;&lt;span&gt;differences of geometry&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span&gt;free combinations of GNSS carrier&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span&gt;phase measurements.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;/span&gt;&lt;span&gt;&lt;/span&gt;&lt;span&gt;&lt;/span&gt;&lt;span&gt;&lt;br&gt;&lt;span&gt;The aim of this work&lt;/span&gt; &lt;span&gt;is to an&lt;/span&gt;&lt;span&gt;a&lt;/span&gt;&lt;span&gt;lyse some&lt;/span&gt; &lt;span&gt;Etna explosions&lt;/span&gt; &lt;span&gt;occurr&lt;/span&gt;&lt;span&gt;ed in 202&lt;/span&gt;&lt;span&gt;1&lt;/span&gt; &lt;span&gt;with the VARION algorithm&lt;/span&gt;&lt;br&gt;&lt;span&gt;in order to&lt;/span&gt; &lt;span&gt;better study the c&lt;/span&gt;&lt;span&gt;oupling between&lt;/span&gt; &lt;span&gt;volcanoes and ionospher&lt;/span&gt;&lt;span&gt;e&lt;/span&gt;&lt;span&gt;. This study can pave the&lt;/span&gt;&lt;br&gt;&lt;span&gt;way to&lt;/span&gt; &lt;span&gt;a re&lt;/span&gt;&lt;span&gt;a&lt;/span&gt;&lt;span&gt;l&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span&gt;ti&lt;/span&gt;&lt;span&gt;me&lt;/span&gt; &lt;span&gt;ionosp&lt;/span&gt;&lt;span&gt;heri&lt;/span&gt;&lt;span&gt;c&lt;/span&gt; &lt;span&gt;monitoring o&lt;/span&gt;&lt;span&gt;f Etna volcano&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;/span&gt;&lt;span&gt;&lt;br&gt;&lt;span&gt;[&lt;/span&gt;&lt;span&gt;1&lt;/span&gt;&lt;span&gt;]&lt;/span&gt; &lt;span&gt;Manta, Fabio, et al. &quot;Correlation between GNSS&amp;#8208;TEC and eruption magnitude supports the use&lt;/span&gt;&lt;br&gt;&lt;span&gt;of ionospheric sensing to complement volcanic hazard assessment.&quot; Journal of Geophysical&lt;/span&gt;&lt;br&gt;&lt;span&gt;Research: Solid Earth 126.2 (2021): e2020JB020726.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;br&gt;&lt;span&gt;[&lt;/span&gt;&lt;span&gt;2&lt;/span&gt;&lt;span&gt;]&lt;/span&gt; &lt;span&gt;Ravanelli, Michela, et al. &quot;GNSS total variometric approach: first demonstration of a tool for&lt;/span&gt;&lt;br&gt;&lt;span&gt;real&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span&gt;time tsunami genesis estim&lt;/span&gt;&lt;span&gt;ation.&quot; Scientific Reports 11.1 (2021): 1&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span&gt;12.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;br&gt;&lt;span&gt;[&lt;/span&gt;&lt;span&gt;3&lt;/span&gt;&lt;span&gt;]&lt;/span&gt; &lt;span&gt;Sava&lt;/span&gt;&lt;span&gt;stano, Giorgio, et al. &quot;Advantages of geostationary satellites for ionospheric anomaly&lt;/span&gt;&lt;br&gt;&lt;span&gt;studies: Ionospheric plasma depletion following a rocket launch.&quot; Remote Sensing 11.14 (2019):&lt;/span&gt;&lt;br&gt;&lt;span&gt;1734.&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;