Verification of the concept of seismoionospheric coupling under quiet heliogeomagnetic conditions, using the Wenchuan (China) earthquake of May 12, 2008, as an example

Sub-ionospheric very low frequency perturbations associated with the 12 May 2008 <i>M</i> = 7.9 Wenchuan earthquake

“…Recently, Pulinets (2009) explained coupling process in terms of global electric circuit, which provides a reasonable explanation of the existence of an up/downward vertical atmospheric electric field between the ground and ionosphere. This quasielectrostatic electric field hypothesis is supported by observations of electric field perturbations before Wenchuan EQ (Sarkar and Gwal 2010;Pulinets et al, 2010;Xu et al, 2011b). Pulinets et al (2010) have observed anomalies in GPS TEC, change in the position and shape of equatorial anomaly crest and variations in vertical electron density profiles before and after the Wenchuan EQ.…”

“…This quasielectrostatic electric field hypothesis is supported by observations of electric field perturbations before Wenchuan EQ (Sarkar and Gwal 2010;Pulinets et al, 2010;Xu et al, 2011b). Pulinets et al (2010) have observed anomalies in GPS TEC, change in the position and shape of equatorial anomaly crest and variations in vertical electron density profiles before and after the Wenchuan EQ. They concluded, on the basis of proper physical model, that observed anomalies were caused by additional electric field (zonal and meridional) generated during the Wenchuan EQ preparation and following the EQ occurrence.…”

“…Pulinets et al (2010) analyzed GPS TEC data from IGS network over Chinese region and found a decrease in TEC before EQ and a sharp increase just after the EQ. Xu et al (2011a) analyzed ionosonde data from Chongqing station (29.55 • N, 106.54 • E) and found significant disturbance in f o F 2 on 9 May 2008 at 17:00 UT.…”

Electromagnetic Anomalies around The Wenchuan Earthquake and Their Relationship with Earthquake Preparation

“…And then many authors presented their studies about that (e.g., [3,[15][16][17][18]). Most anomalies in TEC were found since April 29, and the significant anomaly occurred on May 9, 3 days before the earthquake.…”

Latitudinal distribution of anomalous ion density as a precursor of a large earthquake

“…Although only few ionosphere scientists are actively doing research in the area of precursor effects of the large earthquake, and still many are suspicious about some reported effects [Rishbeth, 2007], the number of the reports has shown significant increase in recent years. Further the quality of the papers appears to be convincing enough to warrant our credibility on such precursor effects on the ionosphere [Dautermann et al, 2007;Zhao et al, 2008;Liu et al, 2009;Pulinets et al, 2010]. Recently the number of reports which use satellite data is increasing [e.g., Parrot et al, 2006;Sharma et al, 2006;Oyama et al, 2008;Bankov et al, 2010].…”