Pre-earthquake Atmospheric and Ionospheric Anomalies before Taiwan Earthquakes (M 6.1 and M 6.4) on February (4th and 6th), 2018

Investigating short-term earthquake precursors detection through monitoring of total electron content variation in ionosphere

“…Xu et al (2011) found that utilizing multiple parameters can reveal the existence of LAI coupling in association with strong earthquakes. Simha et al (2020) support this conclusion and recommend incorporating additional precursory parameters and examining more earthquakes to enhance short-term forecasting models. Sasmal et al (2021), in their study, analyzed different parameters including TEC and magnetic field and found that these parameters are successful in being a convincing pre-seismic signature but with significant differences in their precursory time frames.…”

“…Previous research has demonstrated that the ionospheric variability exhibits distinct characteristics within the seismogenic zone compared to the irregularities outside the area (Pulinets et al, 2007). As shown in Figure 2, most of the precursors were found within the earthquake preparation zone Sharma et al, 2010;Akhoondzadeh and Saradjian, 2011;Hasbi, et al, 2011;Akhoondzadeh, 2012;Choi et al, 2012;Oikonomou et al, 2016;Sharma et al, 2017;Tao et al, 2017;Simha et al, 2020) (Figure 2). However, cautioned that the ionospheric irregularity does not necessarily only appear within the epicenter area as it could be displaced along the geomagnetic field lines towards the magnetic equator, which lies equatorward of the vertical projection of the epicenter of the forthcoming seismic activity on the ionosphere.…”

“…The study by Sharma et al (2017) demonstrated that the TEC concentration increases when the distance from the epicenter decreases. Due to these theories, many researchers have applied the concept of earthquake preparation area that was initially introduced by Dobrovolsky et al (1979) to calculate the effective radius of the seismogenic zone, using the elastic deformation calculations, where R and M are the radius of the effective seismogenic zone and magnitude of the earthquake, respectively Sharma et al, 2010;Akhoondzadeh and Saradjian, 2011;Hasbi, et al, 2011;Akhoondzadeh, 2012;Choi et al, 2012;Oikonomou et al, 2016;Sharma et al, 2017;Tao et al, 2017;Simha et al, 2020).…”

“…The variability of ionospheric variations makes it difficult to distinguish the anomalies caused by enhanced pre-seismic activity The number of earthquakes with precursors in relationship with the earliest time it was detected before earthquake, and size of magnitude based on previous studies (Naaman et al, 2001;Pulinets et al, 2007;Afraimovich and Astafyeva, 2008;Sharma et al, 2010;Zhao et al, 2010;Akhoondzadeh and Saradjian, 2011;Hasbi et al, 2011;Kon et al, 2011;Saradjian and Akhoondzadeh, 2011;Xu et al, 2011;Zolotov et al, 2011;Akhoondzadeh, 2012;Choi et al, 2012;Zhu et al, 2013;Lin, 2014;Tang et al, 2015;Daneshvar and Freund, 2016;Oikonomou et al, 2016;Jiang et al, 2017;Sharma et al, 2017;Tao et al, 2017;Akpan et al, 2019;Li et al, 2019;Shi et al, 2019;Yang et al, 2019;Simha et al, 2020;Tachema and Nadji, 2020;Chen et al, 2021;Mahmoudian and Ghayour, 2021;Mehdi et al, 2021;Sasmal et al, 2021;Dong et al, 2022).…”

On the Correlation Between Earthquakes and Prior Ionospheric Scintillations Over the Ocean: A Study Using GNSS-R Data Between 2017 and 2021

“…Many works have studied the ionospheric perturbations induced by seismic activity, notably by the Total Electron Content (TEC) variations after the earthquakes [2], [3]. It is believed that IS prior to the earthquake originated from a piezo-electric effect created by the compression and later fracture of the rocks due to geological activities [5]. This piezo-electric effect creates fluctuating electric and magnetic fields, which perturb the ionosphere [4], [5].…”