Global Positioning System detection and energy estimation of the ionospheric wave caused by the 13 July 2003 explosion of the Soufrière Hills Volcano, Montserrat

Abstract

[1] Volcanic explosions or shallow earthquakes are known to trigger acoustic and gravity waves that propagate in the atmosphere at infrasonic speeds. At ionospheric heights, coupling between neutral particles and free electrons induces variations of electron density detectable with dual-frequency Global Positioning System (GPS) measurements. Using GPS data collected in the Caribbean, we identified an ionospheric perturbation after a major volcanic explosion at the Soufrière Hills Volcano (Montserrat, Lesser Antilles) on 13 July 2003. Spectral analysis reveals peaks centered at 1 and 4 mHz, similar to those in previous observations and consistent with theory, suggesting both gravity and acoustic wave components. We retrieve a horizontal velocity of $624 m/s for the acoustic component, which implies upward propagation at $33°, consistent with ray-tracing results. We model the acoustic wave using an N-wave pressure source at ground level combined with ray tracing to propagate the neutral pressure wave; this accounts for the dispersive characteristics of the atmosphere while conserving total acoustic energy. Plasma velocity is derived from neutral velocity using a finite difference solution of the magnetohydrodynamic momentum equation. The continuity equation for charge densities is used to compute corresponding electron density variations, which are then numerically integrated along satellite-to-receiver line of sights, simultaneously accounting for the satellite displacements. We minimize the misfit between observed and model waveforms to estimate a total acoustic energy release of 1.53 Â 10 10 J for the primary explosion event at Soufrière Hills Volcano associated with the peak dome collapse. This method can be applied to any explosion of sufficient magnitude, provided GPS data are available at near to medium range from the source.

Detecting ionospheric TEC perturbations caused by natural hazards using a global network of GPS receivers: The Tohoku case study

“…For instance, the eruption of the Soufrière Hills Volcano at Montserrat in 2003 was accompanied by multiple earthquakes and a small tsunami (Dautermann et al, 2009a). More recently, a magnitude 9.0 earthquake occurred on March 11, 2011 at 05:46:23 Universal Time off the coast of Japan, heavily affecting the northern region of Tohoku, as well as the rest of the nation.…”

Localized field-aligned currents and 4-min TEC and ground magnetic oscillations during the 2015 eruption of Chile’s Calbuco volcano

“…After volcanic eruption (e.g., Heki 2006;Dautermann et al 2009) or massive tornado (e.g., Nishioka et al 2013), disturbances in total electron content (TEC) have been observed. After great earthquakes, short-period magnetic and atmospheric pressure oscillations (e.g., Iyemori et al 2005Iyemori et al , 2013 or TEC variations (e.g., Otsuka et al 2006;Saito et al 2011) were observed.…”

Dependence of waveform of near-field coseismic ionospheric disturbances on focal mechanisms

“…They propagate upward and grow in amplitude by several orders of magnitude as they attain ionosphere heights through the decreasing atmospheric density. Such waves can initiate the ionospheric plasma motion due to the collision interaction between neutral and charged particles, and produce perceptible perturbations in the ionosphere electron density (Calais and Minster, 1998;Artru et al, 2001;Heki and Ping, 2005;Astafyeva and Afraimovich, 2006;Dautermann et al, 2008). Do the initial motion polarities of such ionospheric disturbances depend, like P-waves, on the earthquake focal mechanisms?…”