A Preliminary Study on Ionospheric Scintillation Anomalies Detected Using GNSS-R Data from NASA CYGNSS Mission as Possible Earthquake Precursors

Abstract

Ionospheric perturbations affect the propagation of electromagnetic waves. These perturbations, besides being a problem for space communications, satellite navigation, and Earth observation techniques, could also be used as another Earth observation tool. Several recent studies showed correlations with earthquakes with ionospheric anomalies, but almost all of them use ground stations to measure the Total Electron Content (TEC) variations, and, in particular, the ones occurring after an earthquake. Here, a preliminary study is presented on how the ionospheric scintillation measured with GNSS-R instruments over oceanic regions shows a small, but detectable correlation with the occurrence of earthquakes, which in some cases occurs before the earthquakes. This study uses GNSS-R data from NASA CYGNSS Mission to measure the ionospheric amplitude scintillation (S4) for 6 months from March 2019 to August 2019, applying a statistical analysis based on confusion matrixes, and the Receiver Operating Characteristic (ROC) curves to correlate S4 anomalous variations to earthquakes. A small positive correlation is found between the ionospheric scintillation and the earthquakes during the six previous days. However, the study has some weakness because (a) a small number (∼45) of large (M > 6) earthquakes over oceanic regions are studied, (b) the region studied is close to the geomagnetic equator, where ionospheric scintillations are usual, and (c) the overall correlation is small.

First Results on the Systematic Search of Land Surface Temperature Anomalies as Earthquakes Precursors

“…The results of the pre-earthquake LST anomalies detected before strong and moderate earthquakes (M w ≥ 4) studied in this work may be used in the future in conjunction with other proxies for short-term earthquake risk prediction. In addition, we can reuse the same model for other parameters, notably ionospheric scintillation parameters [48,49].…”

Ionosphere Monitoring with Remote Sensing

“…These studies take advantage of GPS data from ground stations or ionosondes to measure the scintillation index S4 and study its correlation with earthquakes in the same region. By using statistical tools, Molina et al [87] for the first time used the GNSS reflectometry [88] technique to obtain global oceanic maps of ionospheric scintillation and correlate them to earthquake precursors. Their results point out a small positive correlation for earthquakes with magnitudes above 4, with better results for increasing magnitudes.…”

Variation in the VLF signal noise amplitude during the period of intense seismic activity in Central Italy from 25 October to 3 November 2016

“…In a large number of scientific studies published in this and the previous century, different types of ionospheric disturbances that precede earthquakes (EQs) are shown (Davies and Baker, 1965;Leonard et al, 1965;Yuen et al, 1969;Calais and Minster, 1998;Maekawa et al, 2006;Sasmal and Chakrabarti, 2009;Chakrabarti et al, 2010;Oyama et al, 2016;Xiong et al, 2021;He et al, 2022;Molina et al, 2022). The repetition of the same or very similar characteristics of these disturbances indicates the possibility that they are precursors of earthquakes, which is why a relevant both theoretical and experimental research is of great importance.…”