Ionospheric variations observed by the DEMETER satellite in the mid-latitude region during strong earthquakes

The French micro-satellite DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) was launched on June 29, 2004. The orbit of DEMETER is polar, circular with an altitude of 710 km. The main scientific objective of this mission is to study the ionospheric perturbations, which may be linked to seismic activity. To achieve this, the payload of DEMETER allows the measurement of some important plasma parameters (ion composition, electron density, temperature and energetic particles). This paper presents examples of electron and ion density irregularities simultaneously observed for three earthquakes that occurred in the mid-latitude region. The DEMETER in situ measurements show the presence of electron and ion density irregularities near the epicenter of these earthquakes. These perturbations were recorded by the ISL (Langmuir Probe) and IAP (thermal plasma analyzer) experiments onboard DEMETER. The repetitiveness of the perturbations close to the epicenters is shown for these three events.