Ionospheric quasi-static electric field anomalies during seismic activity in August–September 1981

Abstract

Abstract. The paper proposes new results, analyses and information for the plate tectonic situation in the processing of INTERCOSMOS-BULGARIA-1300 satellite data about anomalies of the quasi-static electric field in the upper ionosphere over activated earthquake source regions at different latitudes. The earthquake catalogue is made on the basis of information from the United State Geological Survey (USGS) website. The disturbances in ionospheric quasistatic electric fields are recorded by IESP-1 instrument aboard the INTERCOSMOS-BULGARIA-1300 satellite and they are compared with significant seismic events from the period 14 August-20 September 1981 in magnetically very quiet, quiet and medium quiet days. The main tectonic characteristics of the seismically activated territories are also taken in account. The main goal of the above research work is to enlarge the research of possible connections between anomalous vertical electric field penetrations into the ionosphere and the earthquake manifestations, also to propose tectonic arguments for the observed phenomena. The studies are represented in four main blocks: (i) previous studies of similar problems, (ii) selection of satellite, seismic and plate tectonic data, (iii) data processing with new specialized software and observations of the quasi-static electric field and (iiii) summary, comparison of new with previous results in our studies and conclusion. We establish the high informativity of the vertical component Ez of the quasi-static electric field in the upper ionosphere according observations by INTERCOSMOS-BULGARIA-1300 that are placed above considerably activated earthquake sources. This component shows an increase of about 2-10 mV/m above sources, situCorrespondence to: M. Gousheva (gousheva@space.bas.bg) ated on mobile structures of the plates. The paper discusses the observed effects. It is represented also a statistical study of ionospheric effects 5-15 days before and 5-15 days after the earthquakes with magnitude M 4.8-7.9.

Generation of Seismic-Related DC Electric Fields and Lithosphere-Atmosphere-Ionosphere Coupling

“…The DC electric field 5-10 mV/m was detected in the magnetic conjugate regions 11-13 hours before two EQs (magntitude around 5) occurring on 25.08.1981 at 16:54:39 UT and 17:29:07 UT correspondingly (Gousheva et al, 2008). Statistical analyses of the satellite data by Gousheva et al (2008Gousheva et al ( , 2009) led them to make a conclusion on the existence of seismic-related quasi-static electric field in the ionosphere. The duration of electric field disturbances with amplitude of the order of 10 mV/m can be up to 15 days, and the electric field disturbances in the daytime and nighttime ionospheres were on the same order.…”

“…Subsequent investigations of DC electric field in the ionosphere based on direct satellite measurements over seismic regions were carried out by Gousheva et al (2006Gousheva et al ( , 2008Gousheva et al ( , 2009, who analyzed hundreds of seismic events in order to detect DC electric field enhancement in the ionosphere connected with EQs. Seismic events with different magnitudes in different tectonic structures at different latitudes were observed.…”

Manifestations of the earthquake preparations in the ionosphere total electron content variations

“…Numerical simulations using the Upper Atmosphere Model (it would be described below) showed that such electric fields are required to produce the observed TEC disturbances [20][21][22]. These estimations and calculations are also in good agreement with the IN-TERCOSMOS-BULGARIA-1300 satellite observations [26][27][28][29], rocket measurements of large intense electric fields in the E-layer of the ionosphere [30] and ionosonde data-derived electric fields' estimations [31] as well as with recent other authors' simulations, e.g. [32][33][34].…”

Geomagnetic conjugate observations of ionospheric disturbances in response to a North Korean underground nuclear explosion on 3 September 2017

“…Based on the observations of the INTERCOSMOS-BULGARIA-1300 satellite and the DEMETER satellite, Gousheva et al (2008Gousheva et al ( , 2009 and Zhang et al (2014) reported ionospheric quasi-static electric field perturbations during seismic activity. By using the magnetometer observations, Hao et al (2013) and showed obvious ionospheric current and magnetic field perturbations after the Tohoku earthquake. They proposed that the seismo-traveling atmospheric disturbances (STADs) caused by infrasonic waves can propagate vertically into the ionosphere and modify the E layer Hall and Pedersen conductivity, resulting in background ionospheric electric field and magnetic field disturbances.…”