GNSS-monitoring of Natural Hazards: Ionospheric Detection of Earthquakes and Volcano Eruptions

Abstract:

During the last few decades earthquakes as sources of strong perturbations in the ionosphere have been reported by many researchers, and in the last few years the seismo-ionosphere coupling has been more and more discussed (e.g., Calais and Minster, 1998, Phys. Earth Planet. Inter., 105, 167–181; Afraimovich et al., 2010, Earth, Planets, Space, V.62, No.11, 899-904; Rolland et al., 2011, Earth Planets Space, 63, 853–857). Co-volcanic ionospheric perturbations have come under the scrutiny of science only in recent years but observations have already shown that mass and energy injections of volcanic activities can also excite oscillations in the ionosphere (Heki, 2006, Geophys. Res. Lett., 33, L14303; Dautermann et al., 2009, Geophys. Res., 114, B02202).

The ionospheric perturbations are induced by acoustic and gravity waves generated in the neutral atmosphere by seismic source or volcano eruption. The upward propagating vibrations of the atmosphere interact with the plasma in the ionosphere by the particle collisions and excite variations of electron density detectable with dual-frequency receivers of the Global Navigation Satellite System (GNSS). In addition to co-seismic ionospheric disturbances (CID) observations, ionospheric GNSS measurements have recently proved to be useful to obtain ionospheric images for the seismic fault allowing to provide information on its’ parameters and localization (Astafyeva et al., 2011, Geophys. Res. Letters, 38, L22104).

This work describes how the GNSS signals can be used for monitoring of natural hazards on examples of the 9 March 2011 M7.3 Tohoku Foreshock and April 2015 M7.8 Nepal earthquake as well as the April 2015 Calbuco volcano eruptions. We also show that use of high-resolution GNSS data can aid to plot the ionospheric images of seismic fault.